WO2020156504A1

WO2020156504A1 - Quantum communication device and method for quantum communications

Info

Publication number: WO2020156504A1
Application number: PCT/CN2020/074090
Authority: WO
Inventors: 陈巍; 叶文景; 郭欣
Original assignee: 索尼公司; 陈巍
Priority date: 2019-02-01
Filing date: 2020-01-31
Publication date: 2020-08-06
Also published as: CN111525964A

Abstract

The present disclosure relates to a quantum communication device and a method for quantum communications. Specifically, one aspect of the present disclosure relates to a quantum communication device, comprising: an encoding module for generating encoded quantum information; and a control module configured to: determine channel state parameters of a quantum channel; determine reliability requirements for quantum communications; and control, based at least on the channel state parameters and the reliability requirements, the encoding module to generate encoded quantum information.

Description

Quantum communication device and method for quantum communication

Technical field

The present disclosure relates to quantum communication, and in particular to quantum communication devices and methods for quantum communication.

Background technique

Quantum communication is a technical field with great development potential. For example, quantum communication has attracted attention because of its ability to provide efficient and secure information transmission. In recent years, quantum communication has gradually developed from theory to application. Existing quantum communication systems generally use two-dimensional quantum states to represent quantum information, and they use qubits (also called qubits) as the basic information storage unit. The quantum information characterized by qubit is low-dimensional (two-dimensional), and the quantum information has low reliability when passing through a quantum channel, and is not suitable for services that require high reliability. In addition, for different users and environmental conditions, there may be different communication reliability requirements and/or varying quantum channel states. Therefore, flexible customized quantum coding schemes may be required to adapt to changing needs and environmental conditions.

Summary of the invention

One aspect of the present disclosure relates to a quantum communication device, including: an encoding module for generating encoded quantum information; and a control module configured to: determine the channel state parameters of the quantum channel; determine the reliability requirements of the quantum communication; And controlling the encoding module to generate encoded quantum information based on at least the channel state parameters and reliability requirements.

Another aspect of the present disclosure relates to a quantum communication device, including: a decoding module for detecting and decoding quantum information; a control module configured to: determine the channel state parameter of the quantum channel; and control to transmit the channel state parameter To the transmitting device of quantum communication; control the decoding module to detect and decode the encoded quantum information received from the transmitting device.

Another aspect of the present disclosure relates to a method for quantum communication, including: determining a channel state parameter of a quantum channel; determining a reliability requirement of quantum communication; and generating an encoded code based on at least the channel state parameter and the reliability requirement Quantum information.

Another aspect of the present disclosure relates to a method for quantum communication, including: determining a channel state parameter of a quantum channel; transmitting the channel state parameter to a transmitting device of quantum communication; receiving encoded quantum information from the transmitting device; and The encoded quantum information is detected and decoded.

The above solution overview is provided only to provide a basic understanding of the various aspects of the subject described herein. Therefore, the technical features in the above solutions are only examples and should not be construed as limiting the scope or spirit of the subject matter described herein in any way. Other features, aspects and advantages of the subject matter described herein will become apparent from the following specific embodiments described in conjunction with the accompanying drawings.

Description of the drawings

A better understanding of the present disclosure can be obtained when the following detailed description of the embodiments is considered in conjunction with the accompanying drawings. The same or similar reference numerals are used in the various drawings to denote the same or similar components and operations. among them:

Fig. 1 shows a schematic block diagram of a quantum communication system according to an embodiment of the present disclosure.

Fig. 2 shows a schematic block diagram of a transmitting device for quantum communication according to an embodiment of the present disclosure.

Fig. 3 shows a schematic block diagram of a receiving device for quantum communication according to an embodiment of the present disclosure.

FIG. 4A shows a signaling flowchart for determining channel state parameters of a quantum channel according to an embodiment of the present disclosure.

FIG. 4B shows a signaling flowchart for determining channel state parameters of a quantum channel according to another embodiment of the present disclosure.

Fig. 5 shows a signaling flowchart for customizing a quantum transmission scheme based on channel state parameters and reliability requirements according to an embodiment of the present disclosure.

FIG. 6 shows a flowchart of an exemplary method for quantum communication according to an embodiment of the present disclosure.

FIG. 7 shows a flowchart of an exemplary method for quantum communication according to an embodiment of the present disclosure.

Fig. 8 shows a schematic diagram of a quantum circuit for implementing multi-particle encoding according to an embodiment of the present disclosure.

9A and 9B respectively show the average fidelity curves of the multi-particle high-dimensional quantum encoding scheme according to an embodiment of the present disclosure.

Fig. 10 shows a schematic block diagram of an improved quantum communication system model according to an embodiment of the present disclosure.

FIG. 11 shows a schematic diagram of an exemplary implementation of the generalized Pauli operator for qudit.

FIG. 12 shows a schematic diagram of an exemplary implementation of a generalized quantum gate for a single qudit based on OAM.

detailed description

The following describes specific examples of various aspects such as the device and method according to the present disclosure. These examples are described only to add context and help understanding of the described embodiments. Therefore, it is clear to those skilled in the art that the embodiments described below can be implemented without some or all of the specific details. In other cases, well-known operations are not described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are also possible, and the solutions of the present disclosure are not limited to these specific examples.

Quantum Communication System

FIG. 1 shows a block diagram of a quantum communication system 1000 according to an embodiment of the present disclosure. As shown in FIG. 1, the quantum communication system 1000 may include a transmitting device 1100 and a receiving device 1200 for quantum communication. According to some embodiments of the present disclosure, the transmitting device 1100 may be any one of a base station or a user equipment. The receiving apparatus 1200 may be any one of a base station or user equipment. Specific example embodiments of the transmitting device and the receiving device according to the embodiments of the present disclosure are further described below with respect to FIGS. 2 and 3.

According to an embodiment of the present disclosure, in the quantum communication system 1000, the transmitting device 1100 may transmit quantum information to the receiving device 1200 through the quantum channel 1300. The quantum channel 1300 may include any channel known to those skilled in the art that can transmit quantum information. For example, when photons are used to carry quantum information, the quantum channel 1300 may include a propagation channel of photons. It should be noted that although the quantum channel 1300 is shown as a unidirectional channel from the transmitting device 1100 to the receiving device 1200 in FIG. 1, it is clear to those skilled in the art that the quantum channel 1300 may also be bidirectional.

According to an embodiment of the present disclosure, the transmitting device 1100 may also be connected to the receiving device 1200 through at least one additional second channel 1400. The second channel 1400 can be used to transmit various control information and configuration information between the transmitting device 1100 and the receiving device 1200, such as the parameters describing the properties of the reference beam, the channel state parameters of the quantum channel 1300, and the quantum The reliability requirements of communication, etc. According to some embodiments of the present disclosure, the second channel 1400 may be any type of classic channel (for example, a cellular communication channel). According to other embodiments of the present disclosure, the second channel 1400 may be another quantum channel independent of the quantum channel 1300. The second channel 1400 may be a two-way channel, or may include a plurality of one-way sub-channels respectively used for transmission and reception. In addition, although FIG. 1 only shows a single second channel 1400, multiple second channels may exist between the transmitting device 1100 and the receiving device 1200.

According to an embodiment of the present disclosure, the quantum communication system 1000 may also optionally include a system manager 1500. The system manager 1500 may be connected to each of the transmitting device 1100 and the receiving device 1200, and may control the transmitting device 1100 and the receiving device 1200. For example, the system manager 1500 may indicate to the transmitting device 1100 the reliability requirements for quantum communication, and/or scheduling the previous communication between the transmitting device 1100 and the receiving device 1200. According to an embodiment of the present disclosure, any information among the information transmitted through the second channel 1400 may also be transmitted through the system manager 1500 instead. The system manager 1500 is drawn with a dashed line, which indicates that it is optional.

It should be noted that although FIG. 1 shows the quantum communication system 1000 as including one transmitting device 1100 and one receiving device 1200, it will be clear to those skilled in the art that the quantum communication system 1000 may include multiple transmitting devices and/or There are multiple receiving devices, and a similar quantum channel 1300/second channel 1400 can be used for communication between these transmitting devices and receiving devices. One transmitting device can be connected to multiple receiving devices, and/or one receiving device can be connected to multiple transmitting devices. These transmitting devices and receiving devices may share the system manager 1500 or have a dedicated system manager.

Launcher

FIG. 2 shows a schematic block diagram of a transmitting device 2100 for quantum communication according to an embodiment of the present disclosure. The transmitting device 2100 may be implemented as any one of a device on the base station side and a device on the user side. As shown in the figure, the transmitting device 2100 may include a memory 2110, a communication module 2120, an encoding module 2130, and a control module 2140.

According to an embodiment of the present disclosure, the memory 2110 of the transmitting device 2100 may be coupled to one or more other components in the transmitting device 2100, and store information generated by these components or information to be used for these components. For example, the memory 2110 may store information generated by the control module 2140, information received or sent through the communication unit 2120, programs, machine codes and data used for the operation of the transmitting device 2100, and the like. The memory 2110 is drawn with a dashed line, because it may also be located in the control module 2140 or outside the transmitting device 2100. The memory 2110 may be a volatile memory and/or a non-volatile memory. For example, the memory 2110 may include, but is not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), read only memory (ROM), and flash memory.

According to an embodiment of the present disclosure, the communication module 2120 of the transmitting device 2100 may be used to transmit and receive information with one or more external devices. The communication module 2120 may be used to transmit quantum information to a receiving device of quantum communication through a quantum channel (for example, the channel 1300 in FIG. 1). The communication module 2120 may include various suitable implementations. For example, when an optical implementation solution of quantum communication is adopted, the communication module 2120 may be implemented as a corresponding optical device (such as a lens, an optical modulator, etc.). The communication module 2120 may be coupled with one or more other components in the transmitting device 2100, so as to transmit information to or receive information from these components. The communication module 2120 is drawn with a dashed line because it can also be located in the control module 2140 or outside the transmitting device 2100.

Optionally, the communication module 2120 may also be used to receive and send information through a second channel (for example, channel 1400 in FIG. 1). In this case, the communication module 2120 may include a first communication sub-module for the quantum channel and a second communication sub-module for the second channel. The implementation of the second communication sub-module depends on the type of the second channel. When the second channel is a quantum channel of quantum communication using an optical implementation scheme, the second communication sub-module may include a corresponding optical device. In this case, the second communication sub-module may share at least a part of the optical device with the first communication sub-module. When the second channel is a classic channel, the second communication sub-module may include corresponding classic communication elements, such as antenna devices, radio frequency circuits, and/or baseband processing circuits.

It should be noted that although an example embodiment in which the communication module 2120 is used for two channels is described here, the communication module for the second channel may not be a part of the communication module 2120. The communication module for the second channel may be located outside the communication module 2120, or further located outside the transmitting device 2100.

According to an embodiment of the present disclosure, the encoding module 2130 of the transmitting device 2100 may be used to encode the information to be transmitted so as to be suitable for transmission through a corresponding channel. The information to be sent may include quantum information to be transmitted via a quantum channel, and the encoding module 2130 may be used to generate encoded quantum information. To this end, the encoding module 2130 may include various quantum circuits. These quantum circuits can include various quantum gates. Quantum gates can be realized with the help of computer-generated holograms (CGH). When an optical implementation solution of quantum communication is adopted, the encoding module 2130 may include corresponding optical devices (for example, a beam splitter, a half-wave plate, a photonic cavity, etc.). The encoding module 2130 may be coupled with one or more other components in the transmitting device 2100. For example, the encoding module 2130 may be coupled with the control module 2140, and may generate encoded quantum information under the control of the control module 2140. The encoding module 2130 may be configured to encode quantum information according to one or more encoding schemes to generate encoded quantum information. For example, the encoding module 2130 may be configured to generate encoded quantum information according to a multi-particle high-dimensional encoding scheme. The multi-particle high-dimensional coding scheme will be described in further detail later. The encoding module 2130 is drawn with a dashed line because it can also be located in the control module 2140 or outside the transmitting device 2100.

Optionally, the encoding module 2130 can also be used to encode/decode non-quantum information. For example, the encoding module 2130 may be used to encode/decode information transmitted via an additional second channel (for example, channel 1400 in FIG. 1). The second channel may include one or more channels independent of the aforementioned quantum channel. The information transmitted via the second channel may include, for example, parameters describing the properties of the reference beam, the channel state parameters of the quantum channel, the reliability requirements of quantum communication, etc., which will be discussed later. When the second channel is a classic channel, this information can be encoded into classic bit information for transmission via the second channel.

It should be noted that although it is discussed here that the encoding module 2130 can be used to encode both quantum information and non-quantum information, the encoding module used for non-quantum information may not be part of the encoding module 2130. For example, the encoding module for the second channel may be located outside the encoding module 2130, or further located outside the transmitting device 2100.

According to an embodiment of the present disclosure, the transmitting device 2100 may further include a control module 2140. The control module 2140 may take the form of a complete hardware embodiment, a complete software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware. For example, the control module 2140 may include one or more of electrical circuits, optical components, and/or quantum circuits for controlling and implementing the functions described below. According to some embodiments of the present disclosure, the control module 2140 may be implemented as a chip or a microprocessor that executes specific instructions or computer programs, thereby controlling other functional modules to perform specific operations described herein. Specific instructions or computer programs may be stored on a computer-readable storage medium (for example, the memory 2110).

The control module 2140 may be configured to determine the channel state parameters of the quantum channel, determine the reliability requirements of quantum communication, and control the encoding module 2130 to generate encoded quantum information based on at least the channel state parameters and reliability requirements. Optionally, the control module 2140 may include corresponding sub-modules for realizing the above functions and operations, such as a channel state parameter determination module 2141, a reliability requirement determination module 2142, and an encoding parameter determination module 2143. These sub-modules of the control module 2140 are shown as dashed lines in FIG. 2, meaning that they are optional, and therefore can be omitted or combined.

According to an embodiment of the present disclosure, the transmitting device 2100 may perform quantum communication through a quantum channel (for example, the channel 1300 of FIG. 1). There is a type of quantum channel whose noise characteristics may, for example, destroy the phase of quantum information. An example of this type of quantum channel is a phase damped channel. For this type of quantum channel, the phase damping parameter can be used as the channel state parameter to describe the quantum channel. For ease of description, the following describes the solutions of the present disclosure mainly in conjunction with phase damping channels, but it should be understood that these solutions can be similarly applied to the above-mentioned types of quantum channels.

According to an embodiment of the present disclosure, the channel state parameter determination module 2141 in the control module 2140 may be used to determine the phase damping parameter of the quantum channel. To this end, the channel state parameter determination module 2141 may be configured to perform the following operations: the receiving device of vector subcommunication transmits a reference beam; and based at least on the comparison of the transmitted reference beam with the reference beam received at the receiving device, Determine the phase damping parameters. Specifically, the phase damping parameter can be determined based on at least the properties of the emitted reference beam and the properties of the received reference beam; wherein the properties of the emitted reference beam can include one of intensity, emission angle, and emission time. Or multiple, and the attributes of the received reference beam may include one or more of intensity, receiving angle, and receiving time. As an example, the channel state parameter determination module 2141 may be configured to determine the refractive index of light in the quantum channel and the time measurement of interaction between quantum information and the environment by comparing the properties of the transmitted reference beam with the properties of the received reference beam. , And further determine the phase damping parameter based on the refractive index and the time measurement of the interaction of quantum information with the environment. The process of determining the specific embodiment of the phase damping parameter is described later with respect to FIG. 4A and FIG. 4B, and the detailed description is omitted here.

In the above embodiment, in order to determine the phase damping parameter of the quantum channel, the channel state parameter determination module 2141 may be implemented to at least partially include processing logic. The processing logic can be configured to control the generation and emission of the reference beam, control the measurement of the reference beam to obtain various parameters describing the emitted reference beam, and calculate the phase damping parameter based on the comparison of the various parameters describing the properties of the reference beam . Various components (for example, light generators) for realizing reference beam generation, emission, and measurement can be part of the channel state parameter determination module 2141, or can be outside the channel state parameter determination module 2141 and controlled by the module. Perform specific actions. The channel state parameter determination module 2141 may, for example, receive the measurement information from the receiving device of quantum communication via the second channel (for example, the channel 1400 in FIG. 1) through the communication module 2120. As described later with respect to FIGS. 4A-4B, the information may be, for example, a parameter describing the properties of the reference beam received by the receiving device, or may be a phase damping parameter determined by the receiving device.

According to some other embodiments of the present disclosure, the channel state parameter determination module 2141 may not determine the channel state parameters of the quantum channel through the reference beam, but may be indicated by the system manager (for example, the system manager 1500 in FIG. 1). State parameters. For example, the system manager may maintain a channel state parameter table of the quantum channel between each of the one or more transmitting devices in the system and each of the one or more receiving devices. When quantum communication needs to be performed, the channel state parameter determination module 2141 may immediately send a request for acquiring the channel state parameter to the system manager. The request may include, for example, the identification of the transmitting device and the receiving device of the quantum communication. In response to the request, the system manager may return the channel state parameter of the corresponding quantum channel to the channel state parameter determination module 2141 based on the identification of the transmitting device and the receiving device of the quantum communication.

It may be advantageous for the channel state parameter determination module 2141 to determine the channel state parameter instantly. For example, as described further below, the determined channel state parameters can be used to determine the encoding parameters of the quantum encoding scheme, so that the transmitting device 2100 can customize the quantum encoding scheme according to the channel state of the current quantum channel, so as to use different quantum channels. Different quantum coding schemes. It should be noted that, taking into account the changing characteristics of the quantum channel, the determination of the channel state parameters can be performed immediately or periodically.

According to an embodiment of the present disclosure, the reliability requirement determination module 2142 may be configured to determine the reliability requirement of quantum communication. According to an embodiment of the present disclosure, the reliability requirements may include requirements describing the fidelity performance of quantum communication. Fidelity is a core indicator used to measure the reliability of quantum information transmission. The definition of fidelity is described in more detail later, so I won't elaborate on it here.

According to some embodiments of the present disclosure, at least one of the fidelity, minimum fidelity, or average fidelity of quantum communication may be used to describe the reliability requirements, where the minimum fidelity description is the most important in a quantum transmission scheme. Poor fidelity, and average fidelity describes the average of all possible fidelity situations in a quantum transmission scheme.

According to an embodiment of the present disclosure, the reliability requirement determination module 2142 may determine the reliability requirement based on at least one of the following items: the pre-configuration of the transmitting device, the instruction of the receiving device of quantum communication, the network management of quantum communication The instructions of the system or the type of business of quantum communication. In one embodiment, the reliability requirement may be written into the memory 2110 of the transmitting device 2100 in advance and retrieved by the reliability requirement determination module 2142. In another embodiment, the reliability requirement may be sent to the reliability requirement determination module 2142 by the receiving device of quantum communication (for example, the receiving device 1200 in FIG. 1) through the second channel. In another embodiment, the network management system of Quantum Communication (for example, the system manager 1500) may indicate the reliability requirement to the reliability requirement determination module 2142. In another embodiment, the reliability requirement determination module 2142 may determine the reliability requirement based on the service type of quantum communication. For example, you can assign low fidelity requirements to general personal services, medium fidelity requirements to enterprise services, and higher fidelity requirements to military services. In this way, quantum communications with different fidelity performance can be provided for different types of users, and the degree of customization of quantum communications can be improved.

It may be advantageous for the reliability requirement determination module 2142 to determine the reliability requirement in real time. For example, as described further below, the determined reliability requirements can be used to determine the coding parameters of the quantum coding scheme, so that the transmitting device 2100 can customize the quantum coding scheme according to the current reliability requirements of quantum communication, so as to achieve different reliability requirements. Need to use different quantum coding schemes. Therefore, the quantum communication system can implement services with different reliability levels and improve the flexibility of the system.

According to an embodiment of the present disclosure, controlling the encoding module 2130 to generate encoded quantum information by the control module 2140 may include at least: controlling the encoding module 2130 to use a plurality of high-dimensional particles to represent according to a multi-particle high-dimensional quantum encoding scheme by the control module 2140 Encoded quantum information. This process can include constructing a high-dimensional quantum state (for example, dimension d, d>2) and using a multi-particle entangled state composed of multiple high-dimensional quantum states (for example, the number of particles used is N, N≥2) To encode quantum information. Compared with conventional single-particle quantum coding and/or two-dimensional quantum coding, the multi-particle high-dimensional quantum coding scheme has higher fidelity performance. In addition, the multi-particle high-dimensional quantum coding scheme has adjustable coding parameters (for example, the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information), which allows the transmitting device 2100 to adjust according to reliability requirements and channel state parameters. Customize the coding scheme used to provide coding flexibility while ensuring the reliability of quantum communication. More details on the multi-particle high-dimensional quantum encoding scheme will be described further below.

According to an embodiment of the present disclosure, before encoding according to a multi-particle high-dimensional quantum encoding scheme, encoding parameters need to be determined. The encoding parameter determination module 2143 of the control module 2140 may be configured to determine the encoding parameters of the multi-particle high-dimensional quantum encoding scheme based at least on channel state parameters and reliability requirements. The encoding parameter determination module 2143 may receive the phase damping parameter from the channel parameter determination module 2141 as the channel state parameter, and receive the reliability demand of quantum communication from the reliability demand determination module 2142. The encoding parameters of the multi-particle high-dimensional quantum encoding scheme may at least include the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information.

According to an embodiment of the present disclosure, the encoding parameter determination module 2143 can determine the encoding parameters of the multi-particle high-dimensional quantum encoding scheme by looking up a table. For example, a table describing the mapping relationship between phase damping parameters, reliability requirements, and encoding parameters may be maintained in the memory 2110 of the transmitting device 2100. As described further below, this table can be obtained by numerical analysis of the multi-particle high-dimensional quantum coding model. The table may alternatively be stored in another location accessible by the encoding parameter determination module 2143. The encoding parameter determination module 2143 can use the received phase damping parameters and reliability requirements to retrieve the encoding parameters that meet the requirements in the table.

For specific channel state parameters and reliability requirements, there may be multiple sets of candidate coding parameters that meet the reliability requirements. According to an embodiment of the present disclosure, the coding parameter determination module 2143 may be configured to select a group of codes that minimizes the number of high-dimensional quanta used to characterize the encoded quantum information from multiple sets of candidate coding parameters that meet the reliability requirements. parameter. This is because the implementation complexity of the multi-particle high-dimensional quantum coding scheme depends more on the number of high-dimensional particles. By preferentially determining the number parameters of high-dimensional particles, it is possible to reduce the implementation complexity of the multi-particle high-dimensional quantum coding scheme as much as possible while meeting the reliability requirements.

According to an embodiment of the present disclosure, after determining the encoding parameter used, the encoding parameter determination module 2143 may notify the receiving device of the vector communication of the determined encoding parameter. For example, the determined encoding parameter may be sent to the receiving device of quantum communication through the second channel, so that the receiving device can determine a suitable decoding scheme based on the encoding parameter.

According to an embodiment of the present disclosure, quantum orbital angular momentum (OAM) may be used to realize high-dimensional particles. Specifically, d-dimensional (d>2) high-dimensional encoding can be implemented using entangled photons carrying the orbital angular momentum (OAM) state. This is because the wave function represented by OAM has infinite solutions, so the OAM of photons can have infinite states. According to the embodiments of the present disclosure, OAM encoding can be realized through a photonic resonator, thereby converting particles (for example, photons) carrying two-dimensional quantum information into high-dimensional particles carrying high-dimensional quantum information. The photonic resonant cavity can be used as a part of the encoding module 2130, for example. The encoding process will be described in further detail later.

According to an embodiment of the present disclosure, the quantum information encoded by the encoding module 2130 according to the multi-particle high-dimensional encoding scheme may be transmitted via the quantum channel through the communication module 2120. The scheduling of the transmission of quantum information may be predetermined by the transmission device 2100 and/or the system manager (for example, the system manager 1500). Such scheduling may be notified to the receiving device of quantum communication in advance, for example, through the second channel, or the receiving device of quantum communication may be notified by the system manager. The communication module 2120 of the transmitting device 2100 may be configured to perform the transmission of the encoded quantum information according to a predetermined schedule.

It should be noted that although the various components of the transmitting device 2100 for quantum communication are described above with respect to FIG. 2, the transmitting device 2100 may include more or fewer components, or one or more of these components may To be combined, omitted, or divided into multiple sub-components. It will be clear to those skilled in the art that the structure and function of the transmitting device 2100 shown in FIG. 2 can be modified or deformed without departing from the scope of the present disclosure.

Receiving device

FIG. 3 shows a schematic block diagram of a receiving device 3200 for quantum communication according to an embodiment of the present disclosure. The receiving device 3200 may be implemented as any one of a device on the base station side and a device on the user side. As shown in the figure, the transmitting device 3200 may include a memory 3210, a communication module 3220, a decoding module 3230, and a control module 3240.

According to an embodiment of the present disclosure, the memory 3210 of the receiving device 3200 may be coupled to one or more other components in the receiving device 3200, and store information generated by these components or information to be used for these components. For example, the memory 3210 may store information generated by the control module 3240, information received or sent through the communication unit 3220, programs, machine codes, and data used for the operation of the receiving device 3200, and the like. The memory 3210 is drawn with a dashed line because it can also be located in the control module 3240 or outside the receiving device 3200. The memory 3210 may be a volatile memory and/or a non-volatile memory. For example, the memory 3210 may include, but is not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), read only memory (ROM), and flash memory.

According to an embodiment of the present disclosure, the communication module 3220 of the receiving apparatus 3200 may be used to transmit and receive information with one or more external devices. The communication module 3220 may be used to receive quantum information transmitted to the receiving device 3200 through a quantum channel (for example, the channel 1300 in FIG. 1). The communication module 3220 may include various suitable implementations. For example, when an optical implementation solution of quantum communication is adopted, the communication module 3220 may be implemented as a corresponding optical device (for example, a lens, an optical modulator, etc.). The communication module 3220 may be coupled with one or more other components in the receiving device 3200, so as to transmit information to or receive information from these components. The communication module 3220 is drawn with a dotted line because it can also be located in the control module 3240 or outside the receiving device 3200.

Optionally, the communication module 3220 may also be used to receive and send information through a second channel (for example, channel 1400 in FIG. 1). In this case, the communication module 3220 may include a first communication sub-module for the quantum channel and a second communication sub-module for the second channel. The implementation of the second communication sub-module depends on the type of the second channel. When the second channel is a quantum channel of quantum communication using an optical implementation scheme, the second communication sub-module may include a corresponding optical device. In this case, the second communication sub-module may share at least a part of the optical device with the first communication sub-module. When the second channel is a classic channel, the second communication sub-module may include corresponding classic communication elements, such as antenna devices, radio frequency circuits, and/or baseband processing circuits.

It should be noted that although an example embodiment in which the communication module 3220 is used for two channels is described here, the communication module for the second channel may not be a part of the communication module 3220. The communication module for the second channel may be located outside the communication module 3220 or further outside the receiving device 3200.

According to an embodiment of the present disclosure, the decoding module 3230 of the receiving device 3200 may be used to detect and decode the received information to recover the original information. The received information may include encoded quantum information transmitted via a quantum channel, and the decoding module 3230 may be used to detect and decode the encoded quantum information. To this end, the decoding module 3230 may include various quantum circuits. These quantum circuits can include various quantum gates. Quantum gates can be realized with the help of computer-generated holograms (CGH). When the optical implementation solution of quantum communication is adopted, the decoding module 3230 may include corresponding optical devices (for example, a beam splitter, a half-wave plate, a photonic cavity, etc.). The decoding module 3230 may be coupled with one or more other components in the receiving device 3200. For example, the decoding module 3230 can be coupled with the control module 3240, and can detect and decode the received encoded quantum information under the control of the control module 3240. The decoding module 3230 may be configured to encode quantum information according to one or more decoding schemes to detect and decode the encoded quantum information. For example, the decoding module 3230 may be configured to decode the encoded quantum information according to a multi-particle high-dimensional decoding scheme. The multi-particle high-dimensional decoding scheme will be described in detail later. The decoding module 3230 is drawn with a dashed line because it can also be located in the control module 3240 or outside the receiving device 3200.

Optionally, the decoding module 3230 can also be used to encode/decode non-quantum information. For example, the decoding module 3230 may be used to encode/decode information transmitted via an additional second channel (such as channel 1400 in FIG. 1). The second channel may include one or more channels independent of the aforementioned quantum channel. The information transmitted by the second channel may include, for example, parameters describing the properties of the reference beam, the channel state parameters of the quantum channel, the reliability requirements of quantum communication, etc., which will be discussed later. When the second channel is a classic channel, this information can be encoded as classic bit information for transmission via the second channel.

It should be noted that although it is discussed here that the decoding module 3230 can be used to decode both quantum information and non-quantum information, the decoding module used for non-quantum information may not be a part of the decoding module 3230. For example, the decoding module for the second channel may be located outside the decoding module 3230, or further located outside the receiving device 3200.

According to an embodiment of the present disclosure, the receiving device 3200 may further include a control module 3240. The control module 3240 may take the form of a complete hardware embodiment, a complete software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware. For example, the control module 3240 may include one or more of electrical circuits, optical components, and/or quantum circuits for controlling and realizing the functions described below. According to some embodiments of the present disclosure, the control module 3240 may be implemented as a chip or a microprocessor that executes specific instructions or computer programs, thereby controlling other functional modules to perform specific operations described herein. Specific instructions or computer programs may be stored on a computer-readable storage medium (for example, the memory 3210).

The control module 3240 may be configured to determine the channel state parameters of the quantum channel, control to send the channel state parameters to the transmitting device of quantum communication, and control the decoding module to detect and decode the encoded quantum information received from the transmitting device. Optionally, the control module 3240 may include corresponding sub-modules for implementing the above functions and operations, such as a channel state parameter determination module 3241 and a reliability requirement determination module 3242. The channel state parameter determination module 3241 and the reliability requirement determination module 3242 are shown as dashed lines in FIG. 3, which means that it is optional, and therefore can be omitted or combined.

According to an embodiment of the present disclosure, the quantum channel (for example, the channel 1300 of FIG. 1) through which the receiving device 3200 can perform quantum communication may include a phase damping channel. For the phase damping channel, the phase damping parameter can be used as the channel state parameter to describe the quantum channel.

According to an embodiment of the present disclosure, the channel state parameter determination module 3241 in the control module 3240 may be used to determine the phase damping parameter of the quantum channel. To this end, the channel state parameter determination module 3241 may be configured to perform the following operations: receive the reference beam from the transmitting device of the quantum communication; determine the phase damping parameter based at least on the comparison of the transmitted reference beam with the received reference beam. Specifically, the phase damping parameter can be determined based on at least the properties of the emitted reference beam and the properties of the received reference beam; wherein the properties of the emitted reference beam can include one of intensity, emission angle, and emission time. Or multiple, and the attributes of the received reference beam may include one or more of intensity, receiving angle, and receiving time. As an example, the channel state parameter determination module 3241 may be configured to determine the refractive index of light in the quantum channel and the time measurement of interaction between quantum information and the environment by comparing the properties of the transmitted reference beam with the properties of the received reference beam. , And further determine the phase damping parameter based on the refractive index and the time measurement of the interaction of quantum information with the environment. The process of determining the specific embodiment of the phase damping parameter is described later with respect to FIG. 4A and FIG. 4B, and the detailed description is omitted here.

In the above embodiment, in order to determine the phase damping parameter of the quantum channel, the channel state parameter determination module 3241 may be implemented to at least partially include processing logic. The processing logic may be configured to control the reception of the reference beam, control the measurement of the reference beam to obtain various parameters describing the received reference beam, and calculate the phase damping parameter based on the comparison of the various parameters describing the properties of the reference beam. Various components for realizing reference beam reception and measurement may be part of the channel state parameter determination module 3241, or may perform specific operations outside the channel state parameter determination module 3241 and controlled by the module. The channel state parameter determining module 3241 may, for example, send the measurement information to the transmitting device via the second channel (for example, the channel 1400 in FIG. 1) through the communication module 3220. As described later with respect to FIGS. 4A-4B, the information may be, for example, a parameter describing the properties of the received reference beam, or may be a determined phase damping parameter.

As mentioned above, it may be advantageous for the channel state parameter determination module 3241 to determine the channel state parameter in real time. For example, the determined channel state parameters can be used by the transmitting device of quantum communication to determine the coding parameters of the quantum coding scheme, so that the transmitting device can customize the quantum coding scheme according to the channel state of the current quantum channel, so that different quantum channels are used differently. Quantum coding scheme. It should be noted that, taking into account the changing characteristics of the quantum channel, the determination of the channel state parameters can be performed immediately or periodically.

According to an embodiment of the present disclosure, the control module 3240 may optionally include a reliability requirement determination module 3242 configured to determine the reliability requirement of quantum communication and indicate the reliability requirement by the transmitting device of quantum communication. According to an embodiment of the present disclosure, the reliability requirement may include at least one of the fidelity, minimum fidelity, or average fidelity of quantum communication. The reliability requirement determination module 3242 may determine the reliability requirement according to the type of service and the equipment capability, for example, and send the determined reliability requirement to the transmitting device of quantum communication via the second channel. The reliability requirement determination module 3242 is drawn with a dashed line in FIG. 3, which means that it is optional.

It may be advantageous for the reliability requirement determination module 3142 to determine the reliability requirement in real time. For example, the determined reliability requirements can be sent to the transmitting device of quantum communication for determining the coding parameters of the quantum coding scheme, so that the transmitting device can customize the quantum coding scheme according to the current reliability requirements of quantum communication, so that different The reliability requirements use different quantum coding schemes. Therefore, the quantum communication system can implement services with different reliability levels and improve the flexibility of the system.

According to an embodiment of the present disclosure, the encoded quantum information received by the receiving device 3200 may be quantum information characterized by using a plurality of high-dimensional particles according to a multi-particle high-dimensional quantum encoding scheme.

According to an embodiment of the present disclosure, in order to detect and decode quantum information characterized by a plurality of high-dimensional particles, the control module 3240 may be configured to receive encoding parameters describing a multi-particle high-dimensional quantum encoding scheme; and at least based on the encoding Parameters, control the decoding module 3220 to detect and decode the encoded quantum information. The control module 3240 may receive the encoding parameters of the multi-particle high-dimensional quantum encoding scheme from the transmitting device of the quantum communication. These parameters may be determined based on the channel state parameters and the reliability requirements of the quantum communication, and may include at least the encoded The dimension and number of high-dimensional particles of quantum information.

According to an embodiment of the present disclosure, high-dimensional particles used to characterize encoded quantum information may be implemented using quantum orbital angular momentum OAM.

According to an embodiment of the present disclosure, the control module 3240 may control the decoding module 3220 to use a multi-particle high-dimensional recovery operator

The received encoded quantum information is detected and decoded, where ρ represents the received encoded quantum information. For example, for quantum information characterized by N d-dimensional particles, the multi-particle high-dimensional recovery operator

Can be N d-dimensional restoration operators

Kronecker product. The multi-particle high-dimensional recovery operator will be further described later

According to an embodiment of the present disclosure, the scheduling of the reception of quantum information may be predetermined by the transmitting device and/or the system manager (for example, the system manager 1500). Such scheduling may be notified to the receiving apparatus 3200 in advance, for example, through the second channel, or notified to the receiving apparatus 3200 by the system manager. The communication module 3220 of the receiving device 3200 may be configured to perform the reception of the encoded quantum information according to a predetermined schedule.

It should be noted that although various components of the receiving device 3200 for quantum communication are described above with respect to FIG. 3, the receiving device 3200 may include more or fewer components, or one or more of these components may To be combined, omitted, or divided into multiple sub-components. It will be clear to those skilled in the art that the structure and function of the receiving device 3200 shown in FIG. 3 can be modified or deformed without departing from the scope of the present disclosure.

Determine the channel state parameters of the quantum channel

FIG. 4A shows a signaling flowchart 4000A for determining channel state parameters of a quantum channel according to an embodiment of the present disclosure. The transmitting device 4100A shown in FIG. 4A may be, for example, any one of the quantum communication devices 1100 and 2100 described above. The receiving device 4200A may be, for example, any one of the quantum communication devices 1200 and 3200 described above. The transmitting device 4100A may be connected to the receiving device 4200A through a quantum channel (for example, the quantum channel 1300 described in relation to FIG. 1). In addition, the transmitting device 4100A and the receiving device 4200A may also have a second channel independent of the quantum channel (for example, the quantum channel 1400 described in relation to FIG. 1), which is used to transmit additional channels between the transmitting device 4100A and the receiving device 4200A. Information.

In step S4001A, the transmitting device 4100A may be configured to transmit the reference beam to the receiving device 4200A via the quantum channel. The emitted reference beam may have specific attributes, which may include intensity, emission angle, emission time, and so on.

In step S4002A, the transmitting device 4100A may send one or more parameters describing the properties of the transmitted reference beam to the receiving device 4200A. These parameters may be sent through the second channel between the transmitting device 4100A and the receiving device 4200A, for example. The second channel may be, for example, a classical communication channel (for example, a cellular communication channel), or another quantum channel. The transmitted parameters may describe all or some of the intensity, emission angle, and emission time of the reference beam when emitted at the emission device 4100A. For example, the reference beam may be emitted with a predetermined intensity and/or emission angle that can be known to the transmitting and receiving parties, which makes it unnecessary to transmit parameters describing its intensity and emission angle.

When the reference beam propagates through the quantum channel, it will be interfered by environmental factors and therefore suffer a certain loss. For example, the quantum channel may be a phase damped channel. Therefore, when the reference beam reaches the receiving device 4200A via the phase damping channel, its properties will change. The channel state parameters of the quantum channel can be determined based on the comparison of the reference beam emitted at the transmitting device 4100A and the reference beam received at the receiving device 4200A.

In step S4003A, the receiving device 4200A may determine the attributes of the received reference beam. For example, the receiving device 4200A may determine the intensity, receiving angle, receiving time, etc. of the received reference beam through measurement.

In step S4004A, the receiving device 4200A may determine the channel state parameter based at least on the comparison of the attributes of the transmitted reference beam with the attributes of the received reference beam. As mentioned earlier, one or more of the parameters describing the properties of the reference beams emitted may be received by the receiving device 4200A from the transmitting device 4100A in step S4002, and the parameters describing the properties of the received reference beams may be received by the receiving device 4200A. The device 4200A determines in step S4003A.

According to an embodiment of the present disclosure, the channel state parameter describing the channel state may be the phase damping parameter η of the phase damping channel. The phase damping parameter η can be determined according to the following formula, for example:

η＝1-cos ² (χΔt)

Among them, χ represents the electromagnetic susceptibility of the propagation medium in the quantum channel, which is a constant dependent on the type of the propagation medium, and the value of χ can be obtained by querying the propagation medium; Δt represents the time measurement of interaction between quantum information and the environment. According to an embodiment of the present disclosure, the time metric Δt can be determined by the following formula:

Δt=(nn ₀ )L/c

Among them, n represents the refractive index of light in the quantum channel; n ₀ represents the vacuum refractive index, which is a known constant; c represents the vacuum speed of light, which is also a known constant; L represents the distance traveled by the reference beam.

According to an embodiment of the present disclosure, the refractive index n of light in the quantum channel may be known in advance. According to other embodiments of the present disclosure, the value of n can be determined by the following formula:

n=sini/sino

Among them, i represents the emission angle of the reference beam; o represents the reception angle of the reference beam.

According to an embodiment of the present disclosure, the value of L may be known in advance. According to other embodiments of the present disclosure, the value of L can be determined by the following formula:

L=ct ₀ /n

Among them, c represents the speed of light in vacuum; t ₀ represents the difference between the receiving time and the transmitting time of the reference beam; n represents the refractive index of light in the quantum channel.

As such, according to an embodiment of the present disclosure, in order to determine the phase damping parameter η, the receiving device 4200A may determine the refractive index n of the light in the quantum channel, and further determine the refractive index n based on the refractive index n and the time metric Δt for interaction between quantum information and the environment Phase damping parameter η.

In step S4005A, the receiving device 4200A may send the determined phase damping parameter to the transmitting device 4100A. This parameter may be sent through a second channel between the transmitting device 4100A and the receiving device 4200A, for example, which is independent of the currently measured quantum channel.

FIG. 4B shows a signaling flowchart 4000B for determining channel state parameters of a quantum channel according to another embodiment of the present disclosure. The transmitting device 4100B shown in FIG. 4B may be any one of the quantum communication devices 1100 and 2100 described above, for example. The receiving device 4200B may be, for example, any of the quantum communication devices 1200 and 3200 described above. The transmitting device 4100B may be connected to the receiving device 4200B through a quantum channel (for example, the quantum channel 1300 described in relation to FIG. 1). In addition, the transmitting device 4100B and the receiving device 4200B may also have a second channel independent of the quantum channel (for example, the quantum channel 1400 described in relation to FIG. 1), which is used to transmit additional channels between the transmitting device 4100B and the receiving device 4200B. Information.

In step S4001B, the transmitting device 4100B may transmit a reference beam to the receiving device 4200B. This is similar to step S4001A.

In step S4002B, the receiving device 4200B may determine the attributes of the received reference beam. For example, the receiving device 4200B may determine the intensity, receiving angle, receiving time, etc. of the received reference beam through measurement. This is similar to step S4003A in FIG. 4A.

In step S4003B, the receiving device 4200B may send parameters describing the attributes of the received reference beam to the transmitting device 4100B.

In step S4004B, the transmitting device may determine the phase damping parameter based at least on the comparison of the properties of the transmitted reference beam with the properties of the received reference beam. The determining step may be similar to the determining step performed by the receiving device 4200A in step S4004.

It can be seen that, compared with the embodiment shown in FIG. 4A, the difference in the embodiment shown in FIG. 4B is that the transmitting device 4100B does not send parameters related to the properties of the emitted reference beam to the receiving device 4200B. Instead, it can be kept locally for comparison in step S4004B; instead of determining the channel state parameters locally, the receiving device 4200B returns the parameters describing the attributes of the received reference beam to the transmitting device 4100B; and The device 4100B instead of the receiving device 4200B performs the comparison to determine the phase damping parameter, thereby avoiding the receiving device 4200B from sending the phase damping parameter to the transmitting device 4100B. The embodiment shown in FIG. 4B can reduce the burden and complexity of the receiving device 4200B. For a scenario where the receiving apparatus 4200B is a user equipment, this may be advantageous because the user equipment is often limited in terms of cost and complexity.

The process shown in FIGS. 4A-4B allows the channel state parameter of the quantum channel to be determined in real time, thereby enabling the quantum transmission scheme for quantum communication to be customized based on the channel state parameter.

Although the specific signaling process for determining the channel state parameters of the quantum channel is described here with respect to FIGS. 4A-4B, those skilled in the art will understand that the scope of the present invention is not limited to the specific steps disclosed, but may cover each of them. Kinds of modifications and variations. Without departing from the scope of the present disclosure, one or more of these specific steps may be omitted, may include multiple sub-steps, may be performed sequentially, the order may be changed, or may be performed in parallel.

Customize quantum transmission schemes based on channel state parameters and reliability requirements

FIG. 5 shows a signaling flowchart 5000 for customizing a quantum transmission scheme based on channel state parameters and reliability requirements according to an embodiment of the present disclosure. The transmitting device 5100 shown in FIG. 5 may be, for example, any of the

quantum communication devices

1100, 2100, 4100A, and 4100B described above. The receiving device 5200 may be, for example, any one of the

quantum communication devices

1200, 3200, 4200A, and 4200B described above. The transmitting device 5100 may be connected to the receiving device 5200 through a quantum channel (for example, the quantum channel 1300 described in relation to FIG. 1). In addition, the transmitting device 5100 and the receiving device 5200 may also have a second channel independent of the quantum channel (for example, the quantum channel 1400 described in relation to FIG. 1), which is used to transmit additional channels between the transmitting device 5100 and the receiving device 5200. Information.

In step S5001, the transmitting device 5100 may determine the channel state parameters of the quantum channel and determine the reliability requirement of quantum communication.

According to an embodiment of the present disclosure, the channel state parameter of the quantum channel can be determined by the channel state parameter determination module 2141 of the transmitting device 5100. In some embodiments, the phase damping parameter of the quantum channel can be determined through the process described in FIGS. 4A-4B as the channel state parameter describing the quantum channel. In other embodiments, the system manager (for example, the system manager 1500 in FIG. 1) may indicate the channel state parameters to the transmitting device 5100.

According to an embodiment of the present disclosure, the reliability requirements of quantum communication may include describing at least one of the fidelity, minimum fidelity, or average fidelity of quantum communication, where the minimum fidelity is described in a quantum transmission scheme The worst fidelity, and the average fidelity describes the average of all possible fidelity situations in a quantum transmission scheme.

According to an embodiment of the present disclosure, the transmitting device 5100 may determine the reliability requirement based on at least one of the following items (for example, by the reliability requirement determining module 2142): the pre-configuration in the transmitting device 5100, the receiving device 5200 Instructions, instructions from the network management system of quantum communication (for example, the system manager 1500), or service types of quantum communication.

In step S5002, the transmitting device 5100 may (for example, through the encoding parameter determination module 2143) determine the encoding parameters of the multi-particle high-dimensional quantum encoding scheme based at least on the phase damping parameters and the reliability requirements. The multi-particle high-dimensional quantum encoding scheme can use multiple high-dimensional particles to represent the encoded quantum information. The encoding parameters used in this solution include at least the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information. The dimension and quantity can be determined based on phase damping parameters and reliability requirements.

According to the embodiments of the present disclosure, the encoding parameters of the multi-particle high-dimensional quantum encoding scheme can be determined by looking up a table. For example, a table describing the mapping relationship between phase damping parameters, reliability requirements, and encoding parameters may be maintained in the memory of the transmitting device 5100. Alternatively, the table may also be stored in other locations that the transmitting device 5100 can access. The transmitting device 5100 may use the current phase damping parameters and reliability requirements in step S5002 to retrieve the coding parameters that meet the requirements in the table.

According to an embodiment of the present disclosure, when there are multiple sets of candidate encoding parameters that meet the reliability requirements, the transmitting device 5100 can select from the multiple sets of candidate encoding parameters to minimize the number of high-dimensional quanta used to characterize the encoded quantum information A set of encoding parameters.

In step S5003, the transmitting device 5100 may send the determined encoding parameters to the receiving device 5200, thereby allowing the receiving device 5200 to detect and decode the encoded quantum information based on the encoding parameters accordingly. The encoding parameters may be sent through the second channel between the transmitting device 5100 and the receiving device 5200, for example.

In step S5004, the transmitting device 5100 may use a plurality of high-dimensional particles to represent the encoded quantum information according to a multi-particle high-dimensional quantum coding scheme. This process may use the encoding parameters determined in step S5003, and may be implemented, for example, by the control module (for example 2140) of the transmitting device 5100 controlling the encoding module (for example 2130). Specific embodiments of the multi-particle high-dimensional quantum encoding scheme are described in further detail below.

In step S5005, the transmitting device 5100 may transmit quantum information encoded according to a multi-particle high-dimensional quantum encoding scheme. The quantum information can be modulated in the form of light, for example, and propagated through the quantum channel between the transmitting device 5100 and the receiving device 5200.

In step S5006, the receiving device 5200 may detect and decode the received quantum information based on the encoding parameters received in step S5003 to restore the original information. Specific embodiments of the decoding scheme are described in further detail below.

Although the specific signaling process of customizing the quantum transmission scheme based on the channel state parameters and reliability requirements is described with reference to FIG. 5, those skilled in the art will understand that the scope of the present invention is not limited to the specific steps disclosed, but It can cover various modifications and variations. Without departing from the scope of the present disclosure, one or more of these specific steps may be omitted, may include multiple sub-steps, may be performed sequentially, the order may be changed, or may be performed in parallel.

Exemplary method

FIG. 6 shows a flowchart of an exemplary method 6000 for quantum communication according to an embodiment of the present disclosure. As shown in Figure 6, the method 6000 may include determining the channel state parameters of the quantum channel (block 6001) and determining the reliability requirements of the quantum communication (block 6002). The method 6000 may also include generating encoded quantum information based at least on the channel state parameter and the reliability requirement (block 6003). The method 6000 may be executed by, for example, a transmitting device (any of 1100, 2100, 4100A, 4100B, 5100) for quantum communication. The detailed example operation of the method 6000 can refer to the above description of the operation and function of any one of the

transmitting devices

1100, 2100, 4100A, 4100B, and 5100, and a brief description is as follows.

According to an embodiment of the present disclosure, in the method 6000, the channel state parameter includes at least the phase damping parameter of the quantum channel. Determining the phase damping parameter of the quantum channel includes at least: the receiving device of the vector quantum communication transmits a reference beam; and determining the phase damping parameter based at least on the comparison of the emitted reference beam with the reference beam received at the receiving device.

According to an embodiment of the present disclosure, in the method 6000, determining the phase damping parameter based on the comparison at least includes: determining the phase damping parameter based at least on the properties of the transmitted reference beam and the received reference beam; wherein The attributes of the reference beam include one or more of the following: intensity, emission angle, and emission time; wherein the attributes of the received reference beam include one or more of the following: intensity, receiving angle, Receive time.

According to an embodiment of the present disclosure, in the method 6000, determining the phase damping parameter based on the properties of the transmitted reference beam and the properties of the received reference beam at least includes: determining the refractive index n of light in the quantum channel; The refractive index n and the time metric Δt of the interaction between quantum information and the environment are used to determine the phase damping parameter η.

According to an embodiment of the present disclosure, in the method 6000, the reliability requirement includes at least one of the following: fidelity, minimum fidelity, or average fidelity of quantum communication. The reliability requirement may be determined based on at least one of the following: pre-configuration in the quantum communication device; instructions of the receiving device of quantum communication; instructions of the network management system of quantum communication; or service type of quantum communication.

According to an embodiment of the present disclosure, in the method 6000, generating the encoded quantum information includes: using a plurality of high-dimensional particles to characterize the encoded quantum information; wherein the dimensions of the high-dimensional particles used to characterize the encoded quantum information And the number is determined based on at least the channel state parameters and reliability requirements.

According to an embodiment of the present disclosure, the method 6000 may further include determining the encoding parameter by looking up a table.

According to an embodiment of the present disclosure, the method 6000 may further include selecting a set of encoding parameters that minimizes the number of high-dimensional quanta used to characterize the encoded quantum information from among multiple sets of candidate encoding parameters that meet the reliability requirements .

According to an embodiment of the present disclosure, the method 6000 may further include notifying a receiving device of the encoded quantum communication of the determined encoding parameter.

According to an embodiment of the present disclosure, the method 6000 may further include using quantum orbital angular momentum OAM to realize high-dimensional particles.

FIG. 7 shows a flowchart of an exemplary method 7000 for quantum communication according to an embodiment of the present disclosure. As shown in FIG. 7, the method 7000 may include determining the channel state parameters of the quantum channel (block 7001) and sending the channel state parameters to the transmitting device of the quantum communication (block 7002). The method 7000 may also include receiving the encoded quantum information from the transmitting device (block 7003) and detecting and decoding the encoded quantum information (block 7004). The method 7000 may be executed by a receiving device (any one of 1200, 3200, 4200A, 4200B, 5200) for quantum communication, for example. The detailed example operation of the method 7000 can refer to the above description of the operation and function of any one of the receiving

devices

1200, 3200, 4200A, 4200B, and 5200, which are briefly described as follows.

According to an embodiment of the present disclosure, in the method 7000, the channel state parameter includes at least the phase damping parameter of the quantum channel, and determining the phase damping parameter of the quantum channel at least includes: receiving a reference beam from a transmitting device of quantum communication; at least based on the transmitting device The comparison of the emitted reference beam with the reference beam received at the receiving device determines the phase damping parameter.

According to an embodiment of the present disclosure, in the method 7000, determining the phase damping parameter based on the comparison at least includes: determining the phase damping parameter based at least on the properties of the transmitted reference beam and the received reference beam; wherein The attributes of the emitted reference beam include one or more of the following: intensity, emission angle, and emission time; among them, the attributes of the received reference beam include one or more of the following: intensity, reception Angle, receiving time.

According to an embodiment of the present disclosure, in the method 7000, determining the phase damping parameter based on the comparison includes at least: determining the refractive index n of the light in the quantum channel; determining based on the refractive index n and the time metric Δt of interaction between the quantum information and the environment Phase damping parameter η.

According to an embodiment of the present disclosure, the method 7000 further includes sending a reliability requirement of quantum communication to the transmitting device, and the reliability requirement includes at least one of the following: fidelity of quantum communication, minimum fidelity, or average Fidelity.

According to an embodiment of the present disclosure, in the method 7000, the received encoded quantum information is quantum information characterized by a plurality of high-dimensional particles according to a multi-particle high-dimensional quantum encoding scheme.

According to an embodiment of the present disclosure, the method 7000 further includes: receiving an encoding parameter describing a multi-particle high-dimensional quantum encoding scheme; and detecting and decoding the encoded quantum information based at least on the encoding parameter.

According to an embodiment of the present disclosure, in the method 7000, the encoding parameters are determined based on at least the channel state parameters and the reliability requirements of quantum communication.

According to an embodiment of the present disclosure, in the method 7000, the encoding parameters include at least the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information.

According to an embodiment of the present disclosure, in method 7000, high-dimensional particles are implemented using quantum orbital angular momentum OAM.

Although an exemplary method for quantum communication is described here with respect to FIGS. 6 and 7, those skilled in the art will understand that the scope of the present invention is not limited to the specific steps disclosed, but may cover various modifications and transform. Without departing from the scope of the present disclosure, one or more of these specific steps may be omitted, may include multiple sub-steps, may be performed sequentially, the order may be changed, or may be performed in parallel.

Multi-particle high-dimensional quantum encoding and decoding

For the purpose of clarity, here we first briefly introduce the general quantum communication system model, and then describe the error types and mathematical descriptions in quantum communication and the decoding process of classical quantum encoding. Subsequently, the performance indicators for evaluating the reliability of quantum communication are given, and the basic mathematical model of the phase damping channel is described. After introducing the basic background knowledge of quantum communication system, the general performance evaluation index of quantum information processing is introduced. Next, this article presents example embodiments of the multi-particle high-dimensional quantum encoding scheme and the corresponding decoding scheme according to the present disclosure.

A. General quantum communication system model

In classical informatics, bit (bit) is used as the basic information storage unit. In quantum information science, existing quantum communication systems generally use qubits (also known as qubits) as the basic information storage unit. Qubit has two ground states |0> and |1>. For a qubit, its quantum state

It can be expressed as the superposition of two ground states:

Where α and β represent probability amplitudes, and satisfy α ² +β ² =1. Once the quantum state is observed in physics, then

It will collapse to one of the ground states in a very short time. In order to better transmit quantum information, the initial quantum information will be quantum encoded. Assuming that a three-bit repetition code is used, the encoded quantum state

Can be expressed as:

The encoded quantum information will then be transmitted to the receiving end through a quantum channel (for example, a phase damping channel). The receiving device at the receiving end can use a recovery operator to decode the quantum information to obtain the original quantum information. Since in the decoding process, the quantum state will not be directly observed, so

Will not collapse.

B. Error types and decoding steps of quantum coding

Errors in quantum information transmission can be divided into bit flips and phase flips. Bit flipping can be characterized by Pauli operator X, whose function is to flip the quantum state of a qubit from |0> to |1>, or the reverse operation. Therefore, bit flip can be expressed as

For phase reversal, it can reverse the phase of the |1> state. The mathematical expression of phase flip is as follows:

Where Z is the Pauli operator.

If it is a three-bit repetitive code, the possible errors in the quantum channel can be expressed as a group {XXX,XXZ,...,ZZX,ZZZ}, where each element in the group is a possible error type, and each bubble The profit operator can only act on the corresponding quantum code bit. Assuming that only bit flip errors occur in the transmission of the quantum repeat code, the bit flip errors may be at any qubit of the quantum repeat code. At the receiving device, an error detection or syndrome detection operation can be applied to determine whether an error has occurred in the received quantum information and what kind of error has occurred. The detection can be realized by applying a quantum projection operator to the received quantum information. The specific steps are as follows:

Assuming that a bit flip occurs on the first bit, the received quantum state will be α|100>+β|011>. Noticed

Therefore, using the projection operator P ₁ , the observation result will always be 1.

When this type of error is detected, the corresponding recovery operator will act on the received quantum state. For example, if the first bit in the above example is bit flipped, then the recovery operator is to use the X operator for the first qubit. Therefore, errors in the transmission of general quantum information can be detected and corrected.

C. Performance indicators to evaluate the reliability of quantum communication

Although there are many performance indicators for evaluating the reliability of quantum communication, the core performance indicator is fidelity performance. Assuming that ρ and σ are the input quantum and output quantum state of the quantum communication system respectively, the fidelity F(ρ,σ) between ρ and σ can be defined as

The value range of fidelity is [0,1]. The higher the value, the higher the similarity between the input quantum and the output quantum state. For quantum communication, minimum fidelity and average fidelity are the two most commonly used performance indicators, among which minimum fidelity describes the worst fidelity in a transmission scheme , And the average fidelity describes the average of all possible fidelity situations in a transmission scheme.

D. Phase damped channel

When quantum information is transmitted via a quantum channel, since the quantum channel is not a closed system, the emitted quantum information will be affected by noise in the environment. The interaction between quantum information and noise can be regarded as the interaction between the main quantum information system and the environmental system in an open quantum system. The phase damping channel is a very important type of quantum channel, and its noise characteristic is to destroy the phase of quantum information. The phase damped channel can be expressed as:

Where ρ is the input quantum state of the phase damped channel, and ε(ρ) is the output quantum state received via the phase damped channel. In the above formula, E ₀ and E ₁ are the operator elements of the phase damping channel, and the expression is as follows:

Where η is the channel state parameter of the phase damping channel, also known as the phase damping parameter. The value interval of η is [0,1], and the larger the value, the more serious the noise interference.

The above content introduces the general quantum communication system model, describes the error type and mathematical description of quantum communication and the decoding process of classical quantum encoding. In addition, the performance indicators of the reliability of quantum communication and the basic model of the phase damping channel are also given. On this basis, this article provides example embodiments of a multi-particle high-dimensional quantum encoding scheme and corresponding decoding schemes according to the present disclosure.

E. High-dimensional quantum coding

A general quantum communication system uses only two ground states of 0 and 1, and uses qubit based on these two ground states to encode quantum information. The quantum information characterized by qubit is low-dimensional (two-dimensional), and this quantum information has low reliability when passing through a quantum channel, and therefore is not suitable for services that require high reliability.

In order to improve the reliability of quantum communication, according to the embodiments of the present disclosure, a two-dimensional qubit can be expanded into a higher-dimensional quantum unit. The parameter d is used to represent the dimension of the high-dimensional quantum unit, and this quantum unit can therefore be called qudit. Compared with using qubit, the quantum information characterized by qudit can have higher reliability (for example, higher fidelity) when passing through the quantum channel.

According to an embodiment of the present disclosure, photons carrying orbital angular momentum (OAM) can be used to characterize qudit, because OAM can have infinite solutions, so it can represent an infinite number of quantum states. Specifically, quantum OAM can use operators

To indicate that

The mathematical expression of each element is:

therefore,

Can be expressed as a quantum operator:

among them,

Is the Planck constant. Can be solved by

Is obtained from the following wave equation

Eigenvalues

Among them, φ _m (φ) is the wave function used to describe the quantum state, and m is the corresponding quantum state, and its value is a non-negative integer value. According to the solution of this formula, the wave function of OAM can have an infinite number of solutions, that is, OAM can be used to characterize quantum states of any dimension. Based on this characteristic of OAM, OAM can be used to characterize the d-dimensional quantum state qudit, and the photons carrying the OAM characterizing qudit can be called high-dimensional particles or high-dimensional photons. d-dimensional high-dimensional particles can have a ground state set

, The high-dimensional particle can be considered to be in the ground state set

A single particle in a superposition of multiple ground states.

For high-dimensional quantum-encoded information, the error types can be divided into bit flips and phase flips characterized by generalized Pauli operators. For example, for d-dimensional high-dimensional particles, bit flip can be expressed by the following formula:

Among them, X is the Pauli operator representing bit flipping; |j> is the ground state set

A ground state in; operator

Represents the modular operation of the quantum state, which satisfies

For d-dimensional high-dimensional particles, the phase flip can be expressed by the following formula:

Z|j>=ω _j |j>

Among them, Z is the Pauli operator representing the phase flip; |j> is the ground state set

A ground state in ω=e ^i2π/d .

Therefore, for high-dimensional quantum-encoded information, the error in the quantum transmission process can be expressed as the following unitary transformation:

X ^a Z ^b |,a,b∈{0,1,…,d-1}

For any quantum state

You can get:

Z ² (α|0>+β|1>)=α|0>+β|1>

The above formula shows that Z ² is the syndrome of this high-dimensional quantum system. In addition, there is a similar relationship for the generalized Pauli operator X described above. A d×d Fourier matrix H can be defined, each element of which is defined as:

among them

,ω=e ^i2π/d . Then, the characteristic value of the X operator is (

The quantum state defined by the following formula):

For high-dimensional encoded quantum information, the expression of the phase damping channel can be expressed as

among them:

Is the number of combinations, [rho] denotes input before entering the quantum state a quantum channel, ε (ρ) represents the output quantum state a quantum channel, and E _m is the operator information element of high dimensional phase damping channel.

F. Multi-particle high-dimensional quantum coding

Although the use of quantum information characterized by qudit can improve the reliability of quantum communication, this increase in reliability is limited. According to the embodiments of the present disclosure, in order to further improve the reliability of quantum communication, a multi-particle high-dimensional quantum coding scheme may be used. Different from single-particle coding schemes, multi-particle high-dimensional quantum coding schemes can use multiple (for example, N, N≥2) high-dimensional particles (for example, high-dimensional photons that characterize qubit) to encode quantum information, where many A high-dimensional particle is entangled as a whole, rather than simply repeating the code. As will be verified by FIGS. 9A and 9B later, this method can further improve the fidelity of quantum communication. Moreover, in addition to the dimensional parameter d of the high-dimensional particles used, the multi-particle high-dimensional quantum coding scheme also introduces the number parameter N of high-dimensional particles, which further improves the flexibility of coding, thereby allowing the realization of further customized quantum coding.

Next, a specific embodiment of the multi-particle high-dimensional quantum encoding scheme is given. It should be noted that the embodiments given below are only exemplary, and are not intended to limit the scope of the present disclosure to the specific embodiments disclosed. It will be clear to those skilled in the art that various modifications and variations can be made without departing from the scope of the present disclosure.

According to the embodiments of the present disclosure, for d-dimensional high-dimensional particles, the following d-dimensional quantum state can be constructed

with

Among them, d is the dimensional parameter representing the high-dimensional particle, and |j> represents the ground state set corresponding to the d-dimensional high-dimensional particle

The ground state in. According to a preferred embodiment of the present disclosure, d may be selected as d=4k+2 (k is a natural number).

According to an embodiment of the present disclosure, the multi-particle high-dimensional quantum encoding scheme can encode two-dimensional quantum states |0> and |1> into multi-particle high-dimensional quantum states, respectively, and the encoding rule can be expressed as follows:

Among them, N represents the number of entangled high-dimensional particles, N≥2, and N is an encoding parameter independent of d.

For any two-dimensional quantum state characterized as |ρ>=cos(θ/2)|0>+e ^iφ sin(θ/2)|1>|ρ>(where cos(θ/2) and e ^iφ sin(θ/2) respectively represent the probability amplitude of the corresponding ground state), the multi-particle high-dimensional quantum coding scheme can encode the quantum state |ρ> as:

As an example, FIG. 8 shows a schematic diagram of a quantum circuit 8000 for implementing multi-particle encoding according to an embodiment of the present disclosure, where the number of particles parameter N=3. As shown in Fig. 8, the component 8001 can represent a generalized Hadamard gate used in high-dimensional quantum coding.

Can represent the quantum state to be encoded. Quantum state to be encoded

After the quantum circuit shown in Figure 8, we can get

Such a three-bit entangled state.

G. Multi-particle high-dimensional quantum decoding

According to the embodiments of the present disclosure, for the quantum information encoded using the multi-particle high-dimensional quantum encoding scheme, the phase error Z ^±1 can be detected by X ² because of the following properties

For a single high-dimensional particle, the high-dimensional recovery operator

It can be expressed as:

Where ρ represents the input of the recovery operator, and

is defined as

For the multi-particle high-dimensional quantum coding scheme using N high-dimensional particles, the corresponding multi-particle high-dimensional recovery operator

Can be multiple high-dimensional recovery operators

Kronecker product,

Can be expressed as:

among them

It means the Kronecker product, and in physics it means the entangled state of different quantum. The above formula represents the recovery operator of N entangled qudit. Therefore, the above multi-particle high-dimensional restoration operator can be used to restore the received encoded quantum information to the original information.

H. Fidelity of multi-particle high-dimensional quantum coding scheme

First, this article gives an example to show that the minimum fidelity performance of multi-particle high-dimensional quantum coding is better than that of single-particle high-dimensional quantum coding. In this example, N=3, and the coding rules for a 3-particle high-dimensional quantum (qudit) are as follows:

In this case, each qudit will produce a phase error with the probability of p, and p is related to the coefficient of the phase damping channel. Assuming an arbitrary input quantum state

After the encoding, the output quantum state ε is obtained, then the fidelity F between the input quantum state and the output quantum state is calculated as follows:

Among them, the output quantum state ε is as follows

The omitted part in the above formula is the part where the error operator works on more than one qudit. Therefore, the minimum fidelity is as follows:

It can be seen that if p<0.5, the minimum fidelity performance of the 3-particle high-dimensional quantum coding scheme is better than that of the single-particle high-dimensional quantum coding scheme.

The average fidelity is discussed further below. For any quantum state ρ:

The quantum state after N-particle high-dimensional quantum encoding can be expressed as the Kronecker product of N quantum states ρ, namely:

For a single-particle high-dimensional quantum state, the received quantum state ρ ₀ can be expressed by the density matrix as:

among them:

The corresponding received multi-particle high-dimensional quantum state is the Kronecker product of N ρ ₀ , expressed as:

After that, use the recovery operator to decode the received quantum state to obtain the decoded quantum state:

The fidelity between the sent quantum state and the received quantum state in quantum transmission is as follows

Therefore, the average fidelity F _rec will be obtained by calculating the fidelity of all parameters θ and φ

9A and 9B respectively show the average fidelity curves of the multi-particle high-dimensional quantum encoding scheme according to an embodiment of the present disclosure. In Figures 9A-9B, the ordinate represents the fidelity value, and the abscissa represents the phase damping parameter λ of the quantum channel, λ is a variant of the aforementioned phase damping parameter η, and satisfies

The average fidelity curves in FIGS. 9A-9B are, for example, obtained based on the above derivation based on numerical analysis.

In the various coding schemes shown in FIG. 9A, the quantity parameter N=1, and the

curves

9001A, 9002A, 9003A, and 9004A respectively represent the average fidelity curve of the coding scheme with the dimension parameter d=1, 6, 18, and 30 . It can be seen that increasing the dimensionality of a single high-dimensional particle (that is, increasing the dimensional parameter d) can improve the fidelity of quantum communication.

Among the various coding schemes shown in FIG. 9B, the curve 9001B corresponds to the traditional repetitive code scheme with N=1 and high-dimensional qudit is not used, and the curve 9002B corresponds to the multi-particle high-dimensional quantum coding with N=1 and d=6. Scheme, curve 9003B corresponds to the traditional repetitive code scheme with N=3 and high-dimensional qudit is not used, curve 9004B corresponds to the multi-particle high-dimensional quantum coding scheme with N=3 and d=6, curve 9005B corresponds to N=5 and does not The traditional repetitive code scheme using high-dimensional qudit, curve 9006B corresponds to the multi-particle high-dimensional quantum coding scheme with N=5 and d=6. Similar to FIG. 9A, FIG. 9B also shows the fidelity gain of using a high-dimensional quantum coding scheme relative to using a traditional repetitive code scheme (for example, curve 9001B compared with 9002B, curve 9003B compared with 9004B, curve 9005B compared with 9006B) . In addition, by comparing the curves in FIG. 9B (for example, curves 9002B, 9004B, 9006B), it can be seen that increasing the number of high-dimensional particles used for encoding (ie, the number parameter N) can also improve the fidelity of quantum communication.

The numerical analysis of FIGS. 9A-9B shows that by adjusting the coding parameters (dimension parameter d and quantity parameter N) of the multi-particle high-dimensional quantum coding scheme, coding schemes with different fidelity performance can be obtained. The mapping relationship between these parameters, channel state parameters, and fidelity performance can be stored in the table of the quantum communication transmitting device (for example, the

transmitting device

1100, 2100, 4100A, 4100B, 5100). The following Table 1 shows a specific example of such a table, where λ represents a phase damping parameter; and (d, N) represents a set of coding parameters, where d represents a dimensional parameter and N represents a quantity parameter. The values in the table indicate the average fidelity that the multi-particle high-dimensional coding scheme can achieve under the corresponding phase damping parameters and coding parameters. The mapping relationship in Table 1 can be obtained, for example, through numerical analysis similar to FIGS. 9A and 9B. The launch device of quantum communication can use the phase damping parameters and reliability requirements to retrieve the coding parameters that meet the requirements in the table, thereby realizing a customized multi-particle high-dimensional quantum coding scheme. In addition, the complexity of physically implementing multi-particle high-dimensional quantum encoding is related to both N and d, so the smallest N and d that meet the reliability requirements can be selected to minimize the complexity of the system. Further, the priority of the quantity parameter N may be higher than the dimensional parameter d (that is, a group of coding parameters with the smallest N may be preferentially selected), because the quantity parameter N affects the system implementation complexity more.

Table 1 Lookup table for coding parameters, channel state parameters, and fidelity performance

I. Improved quantum communication system model

As shown in Figure 10, on the transmitter side, any two-dimensional quantum state qubit (for example, α|0>+β|1>) can be encoded as a high-dimensional particle qudit (for example, α|0>+β|1>).

The encoding process may be OAM encoding, for example. OAM encoding can be realized by, for example, a photon resonant cavity, so that photons carrying ordinary quantum information are converted into high-dimensional quantum information through optical mode conversion of the resonant cavity. High-dimensional particles qudit (e.g.

It can then be encoded as a multi-particle high-dimensional quantum state (e.g.

The coding parameter N=3 used here. For example, the quantum circuit described in relation to FIG. 8 can be used to implement multi-particle encoding. The high-dimensional quantum coding and multi-particle coding can be performed by the coding module of the transmitting device (for example, the coding module 2130 of FIG. 2). The encoding parameters in the encoding process may be selected according to the channel state parameters of the quantum channel and the reliability requirements of quantum communication, as described above. The encoded multi-particle high-dimensional quantum information can be modulated on the light beam and then transmitted to the receiving device via the quantum channel. It should be noted that the operation on the transmitting device side may also optionally include two-dimensional particle encoding. For example, the operation may encode classical bit information into a two-dimensional quantum state qubit. This operation is drawn with a dashed frame in FIG. 10, indicating that it is optional, and can also be optionally implemented by the encoding module of the transmitting device.

On the receiving device side, the received encoded quantum information can be detected and decoded. The receiving device first detects the received photons to extract the desired photons. This process can be achieved by various optical devices (such as lenses). The photons obtained by detection are multi-particle high-dimensional quantum states (for example

Then, the multi-particle high-dimensional quantum state (e.g.

It can be decoded to obtain a two-dimensional quantum state qubit (for example, α|0>+β|1>). The parameters used for decoding may be based on the encoding parameters received from the transmitting device. The decoding method is, for example, performing a recovery operator on the received photons (such as the multi-particle high-dimensional recovery operator described above). The physical realization can be to let the photon pass through a specific quantum gate first, and then reduce the dimensionality through a resonant cavity . Optionally, the two-dimensional quantum state qubit (α|0>+β|1>) can be further decoded to obtain the original bit information. Some or all of these detection and decoding operations may be performed by the decoding module of the receiving device (for example, the decoding module 3230 of FIG. 2).

One or more operations of the quantum communication system model according to an embodiment of the present disclosure may be physically realized through generalized quantum gates. For qudit coding, the realization of the generalized

Pauli operators

11000A and 11000B can be shown in Figure 11. The realization of generalized quantum gates can be realized by means of integrated optics by means of computer-generated holograms (CGH). As an example, FIG. 12 shows an exemplary implementation of a generalized quantum gate 12000 for a single qudit based on OAM. In Figure 12, the left input is a quantum state, and the output is a quantum state passing through the generalized quantum gate. In the OAM demultiplexing part, for a single qudit of D dimension, the required quantum gate operation can be realized by setting the electro-optical modulator (E/O MOD) in the device.

According to the embodiments of the present disclosure, a quantum information transmission scheme that guarantees the reliability of quantum communication is proposed. Specifically, this article first designs a new multi-particle high-dimensional quantum coding scheme. Numerical analysis shows that by increasing the coding dimension and coding length, the multi-particle high-dimensional quantum coding scheme can obtain better fidelity performance than traditional quantum coding schemes. In addition, by selecting the coding parameters of the multi-particle high-dimensional quantum coding scheme based on the channel state parameters and reliability requirements, a customized coding scheme can be realized, making it possible to achieve the minimum implementation complexity while meeting specific reliability requirements .

It should be noted that although the above embodiments are mainly described for the optical implementation of quantum communication, it will be clear to those skilled in the art that the principles and ideas described in this article can also be used for other implementations of quantum communication. For example, quantum coding and quantum information transmission can also be realized by using ion traps in the nuclear state. The principle of the ion trap is to use the interaction force between the electric charge and the electromagnetic field to restrain the movement of the charged particles, so as to achieve the purpose of confining it to a small range. In this case, the phase damping channel can be modeled as the particles in the ion trap carrying quantum information are affected by electromagnetic field noise, and there will be an operator Rθ that causes the quantum state to produce θ angle rotation, which will affect the quantum information. In the measurement, the angle variance of 2η can be measured by measuring the angle operator θ of the electromagnetic field. η is the phase damping parameter of the phase damping channel. At the same time, the quantum of ion trap can also prepare high-dimensional quantum qudit, so as to realize the multi-particle high-dimensional coding scheme in this paper.

The various aspects of the present disclosure can take the form of a complete hardware embodiment, a complete software embodiment (including firmware, resident software, microcode, etc.), or a combination of software and hardware embodiments, and all the foregoing items can be used herein. It is generally called "circuit", "module" or "system". Any combination of one or more computer-readable storage media can be used. The computer-readable storage medium may be a computer-readable signal medium or a computer-readable storage medium.

The computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any suitable combination of the foregoing. More specific examples (non-exhaustive list) of computer-readable storage media would include the following: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM) ), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any appropriate combination of the foregoing. In the context of this document, a computer-readable storage medium can be any tangible medium that contains or stores a program used by or in combination with an instruction execution system, apparatus, or device.

The present disclosure includes, in various embodiments, configurations, and aspects, components, methods, processes, systems, and/or devices substantially as depicted and described herein, including various embodiments, sub-combinations, and subsets thereof. Those skilled in the art will understand how to make and use the systems and methods disclosed herein after understanding the present disclosure. In various embodiments, configurations, and aspects, the present disclosure includes devices and processes that provide items that are not depicted and/or described herein, or in various embodiments, configurations, or aspects herein, including the absence of Items used in previous devices or processes, for example, to improve performance, implement simplicity, and/or reduce implementation costs.

The solution of the present disclosure can be implemented in the following example manner.

Clause 1. A quantum communication device comprising: an encoding module for generating encoded quantum information; and a control module configured to: determine the channel state parameters of the quantum channel; determine the reliability requirements of quantum communication; and at least based on The channel state parameters and the reliability requirements control the encoding module to generate encoded quantum information.

Clause 2. The quantum communication device according to clause 1, wherein the quantum channel is a phase damping channel.

Clause 3. The quantum communication device according to clause 2, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel.

Clause 4. The quantum communication device according to Clause 3, wherein determining the phase damping parameter of the quantum channel at least includes: the receiving device of the vector quantum communication transmits a reference beam; and at least based on the transmitted reference beam and the receiving device The comparison of the reference beams received at the device determines the phase damping parameter.

Clause 5. The quantum communication device according to clause 4, wherein determining the phase damping parameter based on the comparison at least includes: determining the phase damping based at least on the properties of the transmitted reference beam and the received reference beam Parameters; where the attributes of the emitted reference beam include one or more of the following: intensity, emission angle, emission time; wherein the attributes of the received reference beam include one or more of the following Items: intensity, receiving angle, receiving time.

Clause 6. The quantum communication device according to Clause 5, wherein determining the phase damping parameter based on the properties of the transmitted reference beam and the properties of the received reference beam at least includes: determining the refractive index n of the light in the quantum channel The phase damping parameter η is determined based on the refractive index n and the time metric Δt of interaction between quantum information and the environment; wherein, the time metric Δt of interaction between quantum information and the environment is calculated according to the following equation:

Δt=(nn ₀ )L/c

Where n represents the refractive index of light in the determined quantum channel, n0 represents the refractive index of the vacuum, L represents the optical transmission distance between the quantum communication device and the receiving device, and c represents the speed of light in vacuum; and

Among them, the phase damping parameter η can be calculated according to the following equation:

η＝1-cos ² (χΔt)

Among them, χ represents the electromagnetic susceptibility of the medium of the quantum channel.

Clause 7. The quantum communication device according to Clause 1, wherein the reliability requirement includes at least one of the following: fidelity, minimum fidelity, or average fidelity of quantum communication.

Clause 8. The quantum communication device according to Clause 1, wherein the control module is configured to determine the reliability requirement based on at least one of the following: a pre-configuration in the quantum communication device; quantum The instruction of the receiving device of the communication; the instruction of the network management system of quantum communication; or the type of business of quantum communication.

Clause 9. The quantum communication device according to Clause 1, wherein the control module is further configured to: according to a multi-particle high-dimensional quantum coding scheme, control the coding module to use a plurality of high-dimensional particles to represent the encoded quantum information.

Clause 10. The quantum communication device according to Clause 9, wherein the control module is further configured to determine the encoding of the multi-particle high-dimensional quantum coding scheme based at least on the channel state parameters and the reliability requirements Parameters; wherein the encoding parameters include at least the dimensions and number of high-dimensional particles used to characterize the encoded quantum information.

Clause 11. The quantum communication device according to clause 10, wherein the control module is further configured to determine the encoding parameter by looking up a table.

Clause 12. The quantum communication device according to Clause 10, wherein the control module is further configured to: from a plurality of sets of candidate encoding parameters satisfying the reliability requirements, select the one that is used to characterize the encoded quantum information A set of coding parameters with the smallest number of high-dimensional quanta.

Clause 13. The quantum communication device according to clause 10, wherein the control module is further configured to notify the determined encoding parameter to the receiving device of the quantum communication.

Clause 14. The quantum communication device according to Clause 9, wherein using multiple high-dimensional quanta to characterize the encoded quantum information includes: constructing a d-dimensional quantum state

with

Where d represents the dimension of high-dimensional quantum, d=4k+2, k is a natural number, and d-dimensional quantum state

with

Is structured as:

Using N d-dimensional quantum states

And/or N d-dimensional quantum states

Constitute the N quantum entangled state to encode the quantum state |ρ>, where N represents the number of d-dimensional quantum, N≥2, and is characterized as |ρ>=cos(θ/2)|0>+e ^iφ sin The quantum state|ρ> of (θ/2)|1>, the encoded quantum information is represented as:

Clause 15. The quantum communication device according to Clause 9, wherein quantum orbital angular momentum OAM is used to realize the high-dimensional particles.

Clause 16. The quantum communication device according to Clause 1, wherein the quantum communication device further comprises: a communication module configured to transmit the encoded quantum information via the quantum channel.

Clause 17. A quantum communication device, which includes: a decoding module for detecting and decoding quantum information; a control module configured to: determine the channel state parameters of the quantum channel; control to send the channel state parameters to the quantum Communication transmitting device; controlling the decoding module to detect and decode the encoded quantum information received from the transmitting device.

Clause 18. The quantum communication device according to clause 17, wherein the quantum channel is a phase damping channel.

Clause 19. The quantum communication device according to clause 17, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel.

Clause 20. The quantum communication device according to Clause 19, wherein determining the phase damping parameter comprises: receiving a reference beam from the transmitting device; and determining the phase damping parameter based at least on the comparison of the emitted reference beam with the received reference beam. The phase damping parameter.

Clause 21. The quantum communication device according to Clause 20, determining the phase damping parameter based on the comparison at least includes: determining the phase damping parameter based at least on the properties of the transmitted reference beam and the received reference beam; Wherein, the attributes of the emitted reference beam include one or more of the following: intensity, emission angle, and emission time; wherein, the attributes of the received reference beam include one or more of the following: Strength, receiving angle, receiving time.

Clause 22. The quantum communication device according to Clause 21, determining the phase damping parameter based on the comparison at least includes: determining the refractive index n of the light in the quantum channel; based on the refractive index n and the time measurement of interaction between the quantum information and the environment Δt is used to determine the phase damping parameter η; where the time metric Δt of the interaction between quantum information and the environment is calculated according to the following equation:

Δt=(nn ₀ )L/c

Among them, n represents the refractive index of light in the determined quantum channel, n0 represents the refractive index of the vacuum, L represents the optical transmission distance between the transmitting device and the quantum communication device, and c represents the speed of light in vacuum; and the phase damping parameter η can be based on The following equation is used to calculate:

η＝1-cos ² (χΔt)

Where χ is the electromagnetic susceptibility of the medium of the quantum channel.

Clause 23. The quantum communication device according to Clause 17, wherein the control module is further configured to send a reliability requirement of quantum communication to the transmitting device, and the reliability requirement includes at least one of the following Item: The fidelity, minimum fidelity, or average fidelity of quantum communication.

Clause 24. The quantum communication device according to Clause 17, wherein the received encoded quantum information is quantum information characterized by a plurality of high-dimensional particles according to a multi-particle high-dimensional quantum encoding scheme.

Clause 25. The quantum communication device according to clause 24, wherein the control module is further configured to: receive coding parameters describing the multi-particle high-dimensional quantum coding scheme; and control the coding parameters based at least on the coding parameters The decoding module detects and decodes the encoded quantum information.

Clause 26. The quantum communication device according to Clause 25, wherein the encoding parameter is determined based on at least the channel state parameter and the reliability requirement of quantum communication.

Clause 27. The quantum communication device according to clause 26, wherein the encoding parameters include at least the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information.

Clause 28. The quantum communication device according to Clause 27, wherein a multi-particle high-dimensional recovery operator is used

Detect and decode the received encoded quantum information, multi-particle high-dimensional recovery operator

Are multiple high-dimensional recovery operators

Kronecker product,

Expressed as:

Among them, ρ represents the received encoded quantum information, N represents the number of high-dimensional particles, and the high-dimensional recovery operator

Expressed as:

among them,

is defined as

among them,

Among them, k represents the dimension parameter of the high-dimensional particle, and the dimension d of the high-dimensional particle=2k+1.

Clause 29. The quantum communication device according to Clause 24, wherein the high-dimensional particles are implemented using quantum orbital angular momentum OAM.

Clause 30. A method for quantum communication, wherein the method comprises: determining a channel state parameter of a quantum channel; determining a reliability requirement for quantum communication; and based at least on the channel state parameter and the reliability requirement, Generate encoded quantum information.

Clause 31. The method according to Clause 30, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel, and determining the phase damping parameter of the quantum channel at least includes: a receiving device of vector quantum communication transmits a reference beam And determining the phase damping parameter based at least on the comparison between the reference beam emitted by the transmitting device and the reference beam received at the receiving device.

Clause 32. The method according to Clause 30, wherein generating the encoded quantum information includes: using a plurality of high-dimensional particles to characterize the encoded quantum information; wherein the high-dimensional particles used to characterize the encoded quantum information The dimensions and the number are determined based on at least the channel state parameters and the reliability requirements.

Clause 33. A method for quantum communication, wherein the method comprises: determining a channel state parameter of a quantum channel; sending the channel state parameter to a transmitting device of quantum communication; receiving encoded quantum information from the transmitting device ; And to detect and decode the encoded quantum information.

Clause 34. The method according to clause 33, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel, and determining the phase damping parameter of the quantum channel at least includes: receiving a reference beam from a transmitting device of a quantum communication ; Determine the phase damping parameter based at least on the comparison between the reference beam emitted by the transmitting device and the reference beam received at the receiving device.

Clause 35. The method according to Clause 33, wherein the encoded quantum information is characterized by a plurality of high-dimensional particles, and the method further includes: comparing the encoded quantum information with the encoding parameters of the encoded quantum information. Quantum information is detected and decoded; wherein the coding parameters include the dimensions and the number of high-dimensional particles, and the coding parameters are associated with the channel state parameters and the reliability requirements of quantum communication.

In addition, although the description of the present disclosure has included descriptions of one or more embodiments, configurations, or aspects, certain variations and modifications, other variations, combinations, and modifications are also within the scope of the present disclosure, for example, in the art After the skilled person understands the present disclosure, this may be within the scope of their technology and knowledge. The present disclosure is intended to obtain rights, and the rights shall include alternative embodiments, configurations or aspects within the permitted scope, including alternatives, interchangeable and/or the like with those structures, functions, scopes or steps that are claimed Effective structures, functions, ranges or steps, regardless of whether these alternative, interchangeable and/or equivalent structures, functions, ranges or steps are specifically described herein. This article is not intended to openly contribute any patentable technical solutions.

Claims

A quantum communication device includes:

Encoding module for generating encoded quantum information; and

The control module is configured as:

Determine the channel state parameters of the quantum channel;

Determine the reliability requirements of quantum communication; and

The encoding module is controlled to generate encoded quantum information based on at least the channel state parameter and the reliability requirement.
The quantum communication device of claim 1, wherein the quantum channel is a phase damping channel.
The quantum communication device according to claim 2, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel.
The quantum communication device according to claim 3, wherein determining the phase damping parameter of the quantum channel at least comprises:

The receiving device of vector subcommunication emits a reference beam; and

The phase damping parameter is determined based at least on the comparison of the emitted reference beam with the reference beam received at the receiving device.
The quantum communication device according to claim 4, wherein determining the phase damping parameter based on the comparison at least comprises:

Determining the phase damping parameter based at least on the properties of the emitted reference beam and the received reference beam;

Wherein, the attributes of the emitted reference beam include one or more of the following: intensity, emission angle, emission time;

The attributes of the received reference beam include one or more of the following items: intensity, receiving angle, and receiving time.
The quantum communication device according to claim 5, wherein determining the phase damping parameter based on the properties of the transmitted reference beam and the properties of the received reference beam at least comprises:

Determine the refractive index n of light in the quantum channel;

Determine the phase damping parameter η based on the refractive index n and the time metric Δt of the interaction between quantum information and the environment;

Among them, the time metric Δt of the interaction between quantum information and the environment is calculated according to the following equation:

Δt=(nn 0 )L/c

Where n represents the refractive index of light in the determined quantum channel, n 0 represents the refractive index of the vacuum, L represents the optical transmission distance between the quantum communication device and the receiving device, and c represents the speed of light in vacuum; and

Among them, the phase damping parameter η can be calculated according to the following equation:

η＝1-cos 2 (χΔt)

Among them, χ represents the electromagnetic susceptibility of the medium of the quantum channel.
The quantum communication device according to claim 1, wherein the reliability requirement includes at least one of the following: fidelity, minimum fidelity, or average fidelity of quantum communication.
The quantum communication device according to claim 1, wherein the control module is configured to determine the reliability requirement based on at least one of the following:

Pre-configuration in the quantum communication device;

Instructions of the receiving device of quantum communication;

Instructions from the network management system of Quantum Communication; or

The business type of quantum communication.
The quantum communication device according to claim 1, wherein the control module is further configured to:

According to the multi-particle high-dimensional quantum encoding scheme, the encoding module is controlled to use a plurality of high-dimensional particles to characterize the encoded quantum information.
The quantum communication device according to claim 9, wherein the control module is further configured to:

Determining the coding parameters of the multi-particle high-dimensional quantum coding scheme based at least on the channel state parameters and the reliability requirements;

Wherein, the encoding parameters include at least the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information.
The quantum communication device according to claim 10, wherein the control module is further configured to determine the encoding parameter by looking up a table.
The quantum communication device according to claim 10, wherein the control module is further configured to select, from a plurality of sets of candidate encoding parameters that meet the reliability requirements, a high-dimensionality that is used to characterize the encoded quantum information A set of coding parameters with the smallest number of quanta.
The quantum communication device according to claim 10, wherein the control module is further configured to notify the determined encoding parameter to the receiving device of the quantum communication.
9. The quantum communication device according to claim 9, wherein using a plurality of high-dimensional quanta to characterize the encoded quantum information comprises: constructing a d-dimensional quantum state
with
Where d represents the dimension of high-dimensional quantum, d=4k+2, k is a natural number, and d-dimensional quantum state
with
Is structured as:

Using N d-dimensional quantum states
And/or N d-dimensional quantum states
Constitute the N quantum entangled state to encode the quantum state |ρ>, where N represents the number of d-dimensional quantum, N≥2, and is characterized as |ρ>=cos(θ/2)|0>+e iφ sin The quantum state|ρ> of (θ/2)|1>, the encoded quantum information is represented as:
The quantum communication device according to claim 9, wherein the high-dimensional particles are realized using quantum orbital angular momentum OAM.
The quantum communication device according to claim 1, wherein the quantum communication device further comprises: a communication module configured to transmit the encoded quantum information via the quantum channel.
A quantum communication device, which comprises: a decoding module for detecting and decoding quantum information; a control module configured to: determine the channel state parameters of the quantum channel; and control to send the channel state parameters to the transmission of the quantum communication Device; controlling the decoding module to detect and decode the encoded quantum information received from the transmitting device.
The quantum communication device according to claim 17, wherein the quantum channel is a phase damped channel.
The quantum communication device according to claim 17, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel.
The quantum communication device according to claim 19, wherein determining the phase damping parameter comprises: receiving a reference beam from the transmitting device; and determining the phase based at least on a comparison of the transmitted reference beam with the received reference beam Damping parameters.
The quantum communication device according to claim 20, wherein determining the phase damping parameter based on the comparison at least comprises: determining the phase damping parameter based at least on the properties of the transmitted reference beam and the received reference beam; wherein, The attributes of the emitted reference beam include one or more of the following: intensity, emission angle, and emission time; wherein, the attributes of the received reference beam include one or more of the following: intensity, Receiving angle, receiving time.
The quantum communication device according to claim 21, determining the phase damping parameter based on the comparison at least comprises: determining the refractive index n of the light in the quantum channel; Determine the phase damping parameter η; where the time metric Δt for the interaction between quantum information and the environment is calculated according to the following equation:

Δt=(nn 0 )L/c

Where n represents the refractive index of light in the determined quantum channel, n 0 represents the refractive index of the vacuum, L represents the optical transmission distance between the transmitting device and the quantum communication device, and c represents the speed of light in vacuum; and the phase damping parameter η can be Calculate according to the following equation:

η＝1-cos 2 (χΔt)

Where χ is the electromagnetic susceptibility of the medium of the quantum channel.
The quantum communication device according to claim 17, wherein the control module is further configured to send a reliability requirement of quantum communication to the transmitting device, and the reliability requirement includes at least one of the following: The fidelity, minimum fidelity, or average fidelity of quantum communication.
The quantum communication device according to claim 17, wherein the received encoded quantum information is quantum information characterized by a plurality of high-dimensional particles according to a multi-particle high-dimensional quantum coding scheme.
The quantum communication device according to claim 24, wherein the control module is further configured to: receive encoding parameters describing the multi-particle high-dimensional quantum encoding scheme; and control the decoding module based at least on the encoding parameters Detecting and decoding the encoded quantum information.
The quantum communication device according to claim 25, wherein the encoding parameter is determined based on at least the channel state parameter and the reliability requirement of quantum communication.
The quantum communication device according to claim 26, wherein the encoding parameters include at least the dimensions and the number of high-dimensional particles used to characterize the encoded quantum information.
The quantum communication device according to claim 27, wherein a multi-particle high-dimensional recovery operator is used
Detect and decode the received encoded quantum information, multi-particle high-dimensional recovery operator
Are multiple high-dimensional recovery operators
Kronecker product,
Expressed as:

Among them, ρ represents the received encoded quantum information, N represents the number of high-dimensional particles, and the high-dimensional recovery operator
Expressed as:

among them,
is defined as

among them,

Among them, k represents the dimension parameter of the high-dimensional particle, and the dimension d of the high-dimensional particle=2k+1.
The quantum communication device of claim 24, wherein the high-dimensional particles are implemented using quantum orbital angular momentum OAM.
A method for quantum communication, wherein the method comprises: determining a channel state parameter of a quantum channel; determining a reliability requirement of quantum communication; and generating an encoded data based on at least the channel state parameter and the reliability requirement Quantum information.
The method according to claim 30, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel, and determining the phase damping parameter of the quantum channel at least includes: a receiving device of vector quantum communication transmits a reference beam; and The phase damping parameter is determined based at least on the comparison of the reference beam emitted by the transmitting device with the reference beam received at the receiving device.
The method of claim 30, wherein generating the encoded quantum information comprises: using a plurality of high-dimensional particles to characterize the encoded quantum information; wherein the dimensions of the high-dimensional particles used to characterize the encoded quantum information and The number is determined based on at least the channel state parameter and the reliability requirement.
A method for quantum communication, wherein the method includes: determining a channel state parameter of a quantum channel; transmitting the channel state parameter to a transmitting device of quantum communication; receiving encoded quantum information from the transmitting device; and The encoded quantum information is detected and decoded.
The method according to claim 33, wherein the channel state parameter includes at least a phase damping parameter of the quantum channel, and determining the phase damping parameter of the quantum channel at least includes: receiving a reference beam from a transmitting device of quantum communication; at least The phase damping parameter is determined based on the comparison between the reference beam emitted by the transmitting device and the reference beam received at the receiving device.
The method according to claim 33, wherein the encoded quantum information is characterized by a plurality of high-dimensional particles, and the method further comprises: comparing the encoded quantum information with the encoding parameters of the encoded quantum information Perform detection and decoding; wherein the coding parameters include the dimensions and the number of high-dimensional particles, and the coding parameters are associated with the channel state parameters and the reliability requirements of quantum communication.