CN113098624B - Quantum state measurement method, device, equipment, storage medium and system - Google Patents
Quantum state measurement method, device, equipment, storage medium and system Download PDFInfo
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Abstract
The disclosure provides a quantum state measurement method, a device, equipment, a storage medium and a system, and relates to the field of quantum computation. The specific implementation scheme is as follows: a receiving end receives a quantum state to be processed from a quantum channel, wherein the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system; determining characteristic information of the quantum channel based on a system quantum state of the quantum system; and constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy to obtain a measurement result aiming at the target unknown quantum state. Thus, over-distance measurement is realized.
Description
Technical Field
The present disclosure relates to the field of data processing technology, and more particularly, to the field of quantum computing.
Background
Quantum computing techniques are continually evolving. In consideration of the physical distance between different sites or laboratories, distributed quantum computing becomes an important ring for large-scale quantum computing, however, limited by the current technology, reliable long-distance quantum data transmission has not been realized recently. Therefore, a more practical distributed quantum computing scheme is Local Operations and Classical Communication (LOCC). Wherein, quantum operation generally refers to quantum gate and quantum measurement acting on qubits, and local quantum operation means that each party can only carry out quantum operation on qubits in respective laboratories or sites; classical communication means that only classical information can be transmitted between parties.
As one of the most central parts of quantum computing, quantum measurement can record some characteristics of quantum systems with classical information, such as: hamiltonian quantity, spin, angular momentum and the like, and quantum measurement is one of the most critical steps in quantum computation and bears the important role of extracting classical information. However, under the setting of LOCC, there may be a distance between the observation device (i.e. the measurement device) and the quantum system that is desired to be observed (i.e. measured), i.e. the measurement device needs to measure the non-local quantum system, which is called as over-distance measurement, and may also be considered as a quantum invisible state whose target is to extract classical information by measurement. Therefore, how to efficiently perform over-distance measurement using as few resources as possible is an important issue in quantum technology.
Disclosure of Invention
The disclosure provides a quantum state measurement method, device, equipment, storage medium and system.
According to an aspect of the present disclosure, there is provided a quantum state measurement method including:
a receiving end receives a quantum state to be processed from a quantum channel, wherein the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system;
determining characteristic information of the quantum channel based on a system quantum state of the quantum system;
and constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy to obtain a measurement result aiming at the target unknown quantum state.
According to another aspect of the present disclosure, there is provided a quantum state measurement device applied to a receiving end, including:
the receiving unit is used for receiving a quantum state to be processed from a quantum channel, wherein the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system;
a computing unit for determining characteristic information of the quantum channel based on a system quantum state of the quantum system;
and the denoising unit is used for constructing a denoising strategy based on the characteristic information and denoising the quantum state to be processed based on the constructed denoising strategy so as to obtain a measurement result aiming at the target unknown quantum state.
According to another aspect of the present disclosure, there is provided an electronic device including:
at least one processor; and
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform a method according to any one of the embodiments of the present disclosure.
According to another aspect of the present disclosure, there is provided a non-transitory computer readable storage medium having stored thereon computer instructions for causing a computer to perform a method in any of the embodiments of the present disclosure.
According to another aspect of the present disclosure, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the method in any of the embodiments of the present disclosure.
According to another aspect of the present disclosure, a quantum state measurement system is provided, which includes a receiving end and a transmitting end; wherein the content of the first and second substances,
the transmitting end is used for transmitting the quantum state to be processed through the quantum channel; the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system;
the receiving end is used for receiving the quantum state to be processed from the quantum channel; determining characteristic information of the quantum channel based on a system quantum state of the quantum system; and constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy to obtain a measurement result aiming at the target unknown quantum state.
Techniques according to the present disclosure can efficiently implement over-distance measurements using as few resources as possible.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present disclosure, nor do they limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.
Drawings
The drawings are included to provide a better understanding of the present solution and are not to be construed as limiting the present disclosure. Wherein:
FIG. 1 is a schematic flow chart of an implementation of a quantum state measurement method according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of a quantum state measurement system according to an embodiment of the present disclosure;
FIG. 3 is a schematic flow diagram of a quantum state measurement method in a specific example, according to an embodiment of the disclosure;
FIG. 4 is a schematic flow chart of a structure of a quantum state measurement device according to an embodiment of the present disclosure;
FIG. 5 is a block diagram of an electronic device used to implement the quantum state measurement method of an embodiment of the present disclosure.
Detailed Description
Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings, in which various details of the embodiments of the disclosure are included to assist understanding, and which are to be considered as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present disclosure. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.
The computation process of quantum computation usually ends with quantum measurement, otherwise, the classical information of the computation, i.e. the computation result, cannot be obtained, and therefore, how to implement measurement across sites or laboratories with less cost is very critical to distributed quantum computation. Quantum measurement can be viewed as the process of reacting a given Observable (Observable), denoted as O, with an unknown quantum state ρ to be measured and obtaining an expected value Tr [ op ] (i.e., a measurement). Here, Tr denotes a trace (trace) of the matrix.
For example, Alice and Bob share a quantum system composed of two qubits, specifically, Alice and Bob hold one qubit in the quantum system in their laboratories, the qubit held by Alice is denoted as qubit a, the qubit held by Bob is denoted as qubit B, and the qubit a and the qubit B constitute the quantum system. In practical application, both Alice and Bob can share a quantum system composed of multiple qubits, and at this time, the qubit held by Alice can be recorded as qubit a1、A2，…,AnThe qubit held by Bob can be denoted as qubit B1,B2,…,BmWherein n and m are integers greater than or equal to 2, which is not limited in the scheme of the application. For simplicity, the quantum system shared by Alice and Bob is described as including two qubits; in particular, the quantum state of the quantum system, which may also be referred to as the system quantum state, is denoted as ρABAnd ρ isABIs a Separable state, also known as a non-entangled quantum state. Here, separable refers to a quantum system that can be written as a convex combination of the tensor products of the subsystems, e.g.,
here, i is related to the specific expression of the system quantum state. Alice's laboratory also has a single-bit quantum system (i.e., a quantum system including a qubit, referred to in this example as the quantum system to be measured) that is desired to be observed, and the qubits in the single-bit quantum system are denoted as qubits C, which are in unknown quantum states ρC. Bob's laboratory has an unknown Observable (O) that is used to measure the state information of the quantum system to be measured, i.e., qubit C, in Alice's laboratoryAmount of the compound (A).
Here, it should be noted that the quantum system that Alice holds in the laboratory and is desired to be observed, that is, the quantum system to be measured may further include a plurality of qubits, which is not limited in the present application. For simplicity, this example is only described by taking an example that the quantum system to be measured includes one qubit C, and in practical applications, when the quantum system to be measured includes a plurality of qubits, quantum measurement may be performed on the quantum states of the unknown states in the quantum system to be measured one by one based on the scheme of the present application.
Based on this, the objective task of the scheme of the application is as follows: bob completes the pairing of unknown quantum states rho by means of LOCCCAnd obtaining the expected value Tr [ O ρ ]C]. Here, it is noted that the difficulty is that Bob's laboratory has only the observable O and no qubit C, and in practical applications, Bob can also be targeted according to the computational requirements
Is measured to obtain
The above-mentioned
Refers to quantum operations that Bob may implement locally.
In order to achieve the objective task, the scheme of the application provides an over-distance measurement scheme which can effectively operate on recent quantum devices. Specifically, the scheme can meet the requirement of a multi-party common experiment, and can realize quantum measurement in a more efficient and low-cost mode.
Specifically, fig. 1 is a schematic diagram of an implementation flow of a quantum state measurement method according to an embodiment of the present disclosure, and is applied to a receiving end, where the receiving end may be specifically a quantum device having a quantum hardware structure, or a device having both the quantum hardware structure and a classical data processing capability, or a device having both the quantum hardware structure, the classical data processing capability, and a classical communication capability; the scheme of the application is not limited to the method. Further, as shown in fig. 1, the method includes:
step S101: a receiving end receives a quantum state to be processed from a quantum channel, wherein the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a transmitting end, and the quantum channel is related to the system quantum state of the quantum system. Here, the quantum state to be processed is associated with the quantum channel, which is associated with a system quantum state of the quantum system, on the basis of which the quantum state to be processed is also associated with a system quantum state of the quantum system. In practical application, the quantum state to be processed can be regarded as a quantum state containing noise after the target unknown quantum state acts through the quantum channel.
Step S102: and determining the characteristic information of the quantum channel based on the system quantum state of the quantum system, wherein the characteristic information is specifically an expression form or a mathematical description form of the quantum channel.
Step S103: and constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy to obtain a measurement result aiming at the target unknown quantum state.
Therefore, the quantum noise mitigation technology supported by recent quantum equipment can be used in the scheme of the application, quantum invisible state transfer under a quantum measurement scene can be realized based on any system quantum state, such as separable state or entangled state, and thus, the over-distance measurement of an unknown quantum state (namely a target unknown quantum state) at a sending end is completed at a receiving end. In addition, the dependence on entangled resources is ingeniously avoided in the whole process, and the used resources are reduced to the maximum extent.
In a specific example, the receiving end is located in a laboratory of Bob, that is, the receiving end implements the corresponding operation of Bob in the present application, and the transmitting end is located in a laboratory of Alice, that is, the transmitting end implements the corresponding operation of Alice in the present application, so that Bob implements quantum local operation based on the receiving end, and in a similar way, Alice implements quantum local operation based on the transmitting end.
Here, it is to be noted that in practical application, classical data processing or classical communication may be involved, at this time, Bob may further implement the classical data processing or the classical communication based on the receiving end, and in the same way, Alice may also implement the classical data processing or the classical communication based on the transmitting end, which is not limited in this application scheme.
In a specific example of the present application, quantum measurement on a target unknown quantum state may be implemented in the following manner, specifically, a quantum parameter type to be measured, such as angular momentum, spin, and the like, is determined, and then, based on the constructed denoising strategy, quantum measurement is performed on the to-be-processed quantum state by using a quantum measurement device matched with the quantum parameter type, so as to obtain a measurement result for the target unknown quantum state. At this time, the obtained measurement result is the result matched with the quantum parameter type to be measured. Therefore, the over-distance measurement is realized based on the actual physical measurement requirement, the dependence on entangled resources can be ingeniously avoided in the whole process, and the used resources are reduced to the maximum extent.
In a specific example of the scheme of the application, the performing quantum measurement on the to-be-processed quantum state after the denoising processing based on the quantum measurement device matched with the quantum parameter type to obtain a measurement result for the target unknown quantum state specifically includes: determining observables matching the quantum parameter type; and applying the observable matched with the quantum parameter type to the quantum state to be processed after the denoising processing to obtain a measurement result aiming at the target unknown quantum state. At this time, the obtained measurement result is the result matched with the quantum parameter type to be measured. Therefore, a laboratory-level over-distance measurement scheme is provided, dependence on entangled resources can be ingeniously avoided in the whole process, and the used resources are reduced to the maximum extent.
Here, the observable (observable) is a physical quantity that a physical system can measure. In quantum mechanics, observables are represented as operators that act on physical states (quantum states) to probabilistically obtain a value and irreversibly to a new quantum state, thus enabling quantum measurement of unknown quantum states.
Here, it should be noted that, in an example, it may also be unnecessary to know the quantum parameter type, and at this time, the over-distance measurement may be implemented by using an unknown observable, which is not limited in this application.
In a specific example of the present application, the system quantum state is an entangled state, or a separable state. In other words, the scheme of the application can realize the over-distance measurement in both the entangled state and the non-entangled state. Therefore, the scheme of the application can complete the task of over-distance measurement under the condition of not consuming entangled resources, and provides powerful support for promoting the application and development of recent quantum technologies.
In a specific example of the present disclosure, the quantum system includes at least two qubits, and at least one of the qubits in the quantum system is at the receiving end; the receiving end can perform local quantum operation on local qubits to implement the quantum channel. Therefore, a foundation is laid for realizing the over-distance measurement.
In a specific example of the present application, at least one qubit in the quantum system is located at the sending end, and the sending end can perform local quantum operation on a local qubit to implement the quantum channel. Therefore, a foundation is laid for realizing the over-distance measurement.
That is, in an example, at least one qubit in the quantum system is located at a transmitting end, and at least one other qubit is located at the receiving end, so that the receiving end and the transmitting end share the quantum system. Furthermore, after the receiving end and the sending end perform local quantum operation on the local quantum bit, a quantum channel can be obtained.
In practical application, besides that the receiving end and the sending end share the quantum system, other third parties can share the quantum system, namely other quantum bits in the quantum system can be located in other third parties, so that the quantum system is shared by multiple parties.
Therefore, the quantum noise mitigation technology supported by recent quantum equipment is used in the scheme of the application, and the quantum invisible state transfer under the quantum measurement scene can be realized based on the separable state or the entangled state, so that the over-distance measurement of unknown quantum state is finally completed. And the dependence on entangled resources is ingeniously avoided in the whole process.
Compared with the existing scheme, the scheme of the application has higher practicability on recent quantum equipment, and the unknown quantum state (namely the unknown quantum state rho to be measured held by Alice) does not need to be acquiredC) And therefore the cost is also less. In particular, the scheme of the application can complete the over-distance measurement based on the shared pair of non-entangled quantum pairs, so the cost is lower and the efficiency is higher.
The scheme of the application also provides a quantum state measurement system, as shown in fig. 2, which comprises a receiving end and a transmitting end; wherein the content of the first and second substances,
the transmitting end 201 is configured to transmit a quantum state to be processed through a quantum channel; the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a transmitting end, and the quantum channel is related to the system quantum state of the quantum system.
The receiving end 202 is configured to receive the to-be-processed quantum state from a quantum channel; determining characteristic information of the quantum channel based on a system quantum state of the quantum system; and constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy to obtain a measurement result aiming at the target unknown quantum state.
In a specific example, the receiving end is located in a laboratory of Bob, and the transmitting end is located in a laboratory of Alice, so that Bob realizes quantum local operation based on the receiving end, and in the same way, Alice realizes quantum local operation based on the transmitting end.
Here, it is to be noted that in practical application, classical data processing or classical communication may be involved, at this time, Bob may further implement the classical data processing or the classical communication based on the receiving end, and in the same way, Alice may also implement the classical data processing or the classical communication based on the transmitting end, which is not limited in this application scheme. That is to say, the receiving end may specifically be a quantum device having a quantum hardware structure, or a device having both the quantum hardware structure and a classical data processing capability (for example, implemented based on a memory, a processor, and the like), or a device having both the quantum hardware structure, the classical data processing capability (for example, implemented based on a memory, a processor, and the like), and a classical communication capability (for example, implemented based on a receiver, a transmitter, and the like); similarly, the transmitting end may specifically be a quantum device having a quantum hardware structure, or a device having both the quantum hardware structure and a classical data processing capability (for example, implemented based on a memory, a processor, and the like), or a device having both the quantum hardware structure, the classical data processing capability (for example, implemented based on a memory, a processor, and the like), and a classical communication capability (for example, implemented based on a receiver, a transmitter, and the like); the scheme of the application is not limited to the method.
Therefore, the quantum noise mitigation technology supported by recent quantum equipment is used in the scheme of the application, and the quantum invisible state transfer under the quantum measurement scene can be realized based on the separable state or the entangled state, so that the over-distance measurement of unknown quantum state is finally completed. And the dependence on entangled resources is ingeniously avoided in the whole process.
Compared with the existing scheme, the scheme of the application has higher practicability on recent quantum equipment, and the unknown quantum state (namely the unknown quantum state rho to be measured held by Alice) does not need to be acquiredC) And therefore the cost is also less. In particular, the scheme of the application can complete the over-distance measurement based on the shared pair of non-entangled quantum pairs, so the cost is lower and the efficiency is higher.
The following describes the present application in further detail with reference to specific examples, specifically, in this example, when Alice and Bob share a quantum system including two qubits, when Alice and Bob share a system quantum state ρ, the quantum system ρ is obtainedABAt the maximum entanglement state, the noiseless unknown quantum state rho held by Alice laboratories can be obtained based on the quantum invisible state transfer technologyCAnd transmitted to Bob through a quantum channel. And when the system quantum state rho shared between Alice and BobABWhen the quantum state is not the maximum entangled state or not the entangled state but the separable state, Alice cannot directly convert the unknown quantum state ρCTransmitted to Bob and will instead transmit some noisy quantum states
To Bob, where said
Represents a quantum channel, which is the most fundamental quantum operation that is physically realizable,
depends on the quantum state rho of the system shared by Alice and BobAB(ii) a In the practical application of the method, the air conditioner,
the specific form of (c) also depends on both parties' local quantum operations and classical communication. It should be noted that, when Alice and Bob share a quantum system including multiple qubits, in this case,
still depends on the system quantum state, and the system quantum state is a quantum state formed by a plurality of qubits together.
The present example is based on a method of separable quantum states (i.e., non-entangled states) by constructing quantum channels based on shared system quantum states and LOCC schemes such that Alice passes through the constructed quantum channelsUnknown quantum state rho with noise on transmission bandCI.e. the quantum state to be treated
To Bob, Bob obtains the quantum state to be processed
Thereafter, the expected value Tr [ O ρ ] is estimated by a quantum noise mitigation (Quantum error mitigation) techniqueC]The expected value Tr [ O ρ ]C]That is, Bob (also called receiving end) is responsible for unknown quantum state rhoCQuantum measurement of (2). Specifically, assume that Alice and Bob initially share a system quantum state ρABQuantum state ρ of the systemABBased on a quantum invisible state protocol, Alice and Bob perform local quantum operation on the quantum bit respectively held in the shared quantum system, namely Alice performs local quantum operation on the quantum bit A, and Bob performs local quantum operation on the quantum bit B to obtain a quantum channel, so that Alice performs the held unknown quantum state rhoCThe quantum state to be processed obtained after the action of the constructed quantum channel
Delivered to Bob and the quantum state to be processed
The method can be regarded as that Alice performs local quantum operation on the qubit A, and Bob performs local quantum operation on the qubit B, so that the Bob end obtains the unknown quantum state rho containing noise informationC. At this time, the over-distance measurement problem can be converted into Bob from the quantum state to be processed through the noise channel
Obtaining the expected value Tr [ O ρ ]C]And this problem is exactly the problem that quantum noise mitigation techniques aim to solve.
Briefly, the present example is based on quantum invisible state transfer techniques, and with a shared systemQuantum state, the shared system quantum state can be separable (also can be separated quantum state or non-entangled state), also can be entangled state, and the implemented quantum channel
Then, quantum channels are eliminated during measurement by quantum noise mitigation
The effect of which is to obtain the desired value required. It should be noted that there are many different methods for quantum noise mitigation, and a specific method for quantum noise mitigation is given below as an example for illustration, which is not limited by the present disclosure.
As shown in fig. 3, the specific scheme is as follows:
step 1: both Alice and Bob share a quantum system comprising two qubits, wherein Alice and Bob hold one qubit in their respective laboratories, the qubit held by Alice is denoted as qubit A, the qubit held by Bob is denoted as qubit B, and the system quantum state is denoted as ρAB(ii) a In addition, Alice also has an unknown quantum state ρCThis is an unknown quantum state that needs to be transferred, for which Bob is the unknown quantum state ρCAnd carrying out quantum measurement.
Step 2: alice and Bob utilize the system quantum state ρABAnd implementing quantum channels based on quantum invisible transport protocol techniques
Basing Bob on the quantum channel
Obtaining the quantum state to be processed
And step 3: bob according to quantum channel
In the specific form of (1), a quantum noise mitigation scheme (i.e., a quantum error mitigation scheme) is designed to estimate the expected value Tr [ O ρ [ ]C]. Here, O is an unknown observable at Bob's laboratory for the unknown quantum state ρ in Alice's laboratoryCAnd carrying out quantum measurement.
And 4, step 4: based on system quantum state rhoABIn a particular form, the noise channel is derived
And calculating the noise channel
Inverse mapping of
Here, it is assumed that its inverse mapping exists. In particular, in practical applications, a semi-positive Programming method (Semidefinite Programming) can be used to map the inverse on a classical computer
Performing quasi-probability decomposition:
wherein p is1,p2Is satisfying p1+p2A real number of 1 is defined as,
characterizing physical quantum channels implemented on physical devices requires, in practice, the physical implementation of these physical quantum channels when sampling and estimating the expectation. It is emphasized here that the semi-positive planning method has an efficient classical algorithm, and therefore the quasi-probabilistic decomposition described above can be done efficiently on a classical computer.
Further, let γ ═ p1|+|p2I, design summaryRate distribution
And multiple slave probability distributions
The k-th sampling of the virtual quantum channel is taken as
(
Or
) Memory for recording
Corresponding coefficient is p(k)(p1Or p2) Estimating the estimated expected value obtained by the kth sampling, i.e. applying the observable O to the quantum state obtained by the kth sampling, i.e.
To obtain the expected value
Recording the total sampling times as K, and calculating:
where σ (p) represents the sign of p: if p is a positive number, σ (p) ═ 1; if p is negative, σ (p) — 1. The value of xi is the unknown quantum state rho of BobCMeasured result of (i.e. Tr [ O ρ ]C]) Efficient estimation of (1). Here, theoretical verification shows that the larger the total number K of samples is, the closer the estimated value ξ is likely to be an ideal Tr [ O ρ [ ]C]。
It should be emphasized that the specific design quantum noise mitigation scheme given above is merely exemplary, and in practical applications, there are many other noise mitigation methods that can be used in this step, and the present application is not limited thereto.
In practical applications, in the above embodiment, Bob performs only a quantum measurement locally. In fact, the scheme of the application is also applicable to the situation that Bob needs to do other quantum operations before quantum measurement. This is because, assuming that Bob needs to be obtained
Then the following formula can be obtained according to the linear property, and the pair can be realized based on the following formula
For the purpose of carrying out the measurement, here, the
Refers to quantum operations that Bob may perform locally; the specific formula is as follows:
in addition, in the present embodiment, the system quantum state ρ shared by both Alice and Bob is the system quantum state ρABNot the only. In fact, the system quantum state rho of the scheme of the applicationABIs not limited to the type or specific form of (A), but only the resulting quantum channel of the different type or specific form
Changes occur, at which point Bob only needs to rely on what is received
Quantum noise mitigation is designed.
In addition, the system quantum state shared between Alice and Bob may be a separable state or an entangled state, and when the system quantum state is an entangled state, the scheme of the present application is not limited to the maximum entangled state, in other words, any entangled state may be used.
Meanwhile, the scheme of the application can be simply expanded to the situation of multi-quantum bits, for example, for the quantum state of one N quantum bit, namely under the condition that the unknown quantum state is N, the scheme of the application can realize over-distance measurement on each unknown quantum bit, and finally, the measurement result of the N unknown quantum states is obtained by matching with classical post-processing.
Thus, compared with the existing scheme, the scheme of the application has the following advantages:
firstly, dependence on entangled resources is avoided, and over-distance measurement of quantum states is realized. Namely, the system quantum state is not limited to the maximum entangled state, and for the non-maximum entangled state or the non-entangled state, the scheme of the application can still complete the over-distance measurement, so that the application scene is richer.
Secondly, the scheme of the application uses less resources and is more convenient to operate on the basis of realizing the over-distance measurement; meanwhile, the method has better practicability and expansibility, and can be suitable for the situation of multiple quantum sites.
The present application further provides a quantum state measurement apparatus, which is applied to a receiving end, as shown in fig. 4, and includes:
a receiving unit 401, configured to receive a to-be-processed quantum state from a quantum channel, where the to-be-processed quantum state is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system;
a computing unit 402 configured to determine characteristic information of the quantum channel based on a system quantum state of the quantum system;
a denoising unit 403, configured to construct a denoising strategy based on the feature information, and perform denoising processing on the quantum state to be processed based on the constructed denoising strategy, so as to obtain a measurement result for the target unknown quantum state.
In a specific example of the scheme of the present application, the method further includes:
the type determining unit is used for determining the type of the quantum parameter to be measured;
and the measuring unit is used for carrying out quantum measurement on the quantum state to be processed based on the constructed denoising strategy and by using quantum measuring equipment matched with the quantum parameter type so as to obtain a measuring result aiming at the target unknown quantum state.
In a specific example of the scheme of the present application, the measurement unit is further configured to determine an observable that matches the quantum parameter type; and applying the observable to the quantum state to be processed after the denoising processing to obtain a measurement result aiming at the target unknown quantum state.
In a specific example of the present application, the system quantum state is an entangled state, or a separable state.
In a specific example of the present disclosure, the quantum system includes at least two qubits, and at least one of the qubits in the quantum system is at the receiving end; the receiving end can perform local quantum operation on local qubits to implement the quantum channel.
In a specific example of the present application, at least one qubit in the quantum system is located at the sending end, and the sending end can perform local quantum operation on a local qubit to implement the quantum channel.
The functions of each unit in the quantum state measurement device in the embodiment of the present invention may refer to the corresponding description in the above method, and are not described herein again.
Here, it should be noted that the quantum state measurement apparatus according to the present disclosure may specifically be a quantum device having a quantum hardware structure, or a device having both the quantum hardware structure and a classical data processing capability (for example, implemented based on a memory or a processor), or a device having both the quantum hardware structure, the classical data processing capability (for example, implemented based on a memory or a processor), and a classical communication capability (for example, implemented based on a receiver or a transmitter); the scheme of the application is not limited to the method.
The present disclosure also provides an electronic device, a readable storage medium, and a computer program product according to embodiments of the present disclosure. Here, the electronic device may be embodied as a classic device; alternatively, the device has a quantum hardware structure.
FIG. 5 illustrates a schematic block diagram of an example electronic device 500 that can be used to implement embodiments of the present disclosure. Electronic devices are intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions, are meant to be examples only, and are not meant to limit implementations of the disclosure described and/or claimed herein.
As shown in fig. 5, the electronic device 500 includes a computing unit 501, which can perform various appropriate actions and processes according to a computer program stored in a Read Only Memory (ROM)502 or a computer program loaded from a storage unit 508 into a Random Access Memory (RAM) 503. In the RAM 503, various programs and data required for the operation of the electronic apparatus 500 can also be stored. The calculation unit 501, the ROM 502, and the RAM 503 are connected to each other by a bus 504. An input/output (I/O) interface 505 is also connected to bus 504.
A number of components in the electronic device 500 are connected to the I/O interface 505, including: an input unit 506 such as a keyboard, a mouse, or the like; an output unit 507 such as various types of displays, speakers, and the like; a storage unit 508, such as a magnetic disk, optical disk, or the like; and a communication unit 509 such as a network card, modem, wireless communication transceiver, etc. The communication unit 509 allows the electronic device 500 to exchange information/data with other devices through a computer network such as the internet and/or various telecommunication networks.
The computing unit 501 may be a variety of general-purpose and/or special-purpose processing components having processing and computing capabilities. Some examples of the computing unit 501 include, but are not limited to, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), various dedicated Artificial Intelligence (AI) computing chips, various computing units running machine learning model algorithms, a Digital Signal Processor (DSP), and any suitable processor, controller, microcontroller, and so forth. The calculation unit 501 performs the respective methods and processes described above, such as the quantum state measurement method. For example, in some embodiments, the quantum state measurement method may be implemented as a computer software program tangibly embodied in a machine-readable medium, such as storage unit 508. In some embodiments, part or all of the computer program may be loaded and/or installed onto the electronic device 500 via the ROM 502 and/or the communication unit 509. When the computer program is loaded into RAM 503 and executed by the computing unit 501, one or more steps of the quantum state measurement method described above may be performed. Alternatively, in other embodiments, the computing unit 501 may be configured to perform the quantum state measurement method by any other suitable means (e.g., by means of firmware).
Various implementations of the systems and techniques described here above may be implemented in digital electronic circuitry, integrated circuitry, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), Application Specific Standard Products (ASSPs), system on a chip (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various embodiments may include: implemented in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, receiving data and instructions from, and transmitting data and instructions to, a storage system, at least one input device, and at least one output device.
Program code for implementing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine or entirely on the remote machine or server.
In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is 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 of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to a user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which a user can provide input to the computer. Other kinds of devices may also be used to provide for interaction with a user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form, including acoustic input, speech input, or tactile input.
The systems and techniques described here can be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a user computer having a graphical user interface or a web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local Area Networks (LANs), Wide Area Networks (WANs), and the Internet.
The computer system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.
It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present disclosure may be executed in parallel or sequentially or in different orders, and are not limited herein as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved.
The above detailed description should not be construed as limiting the scope of the disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present disclosure should be included in the scope of protection of the present disclosure.
Claims (13)
1. A quantum state measurement method, comprising:
a receiving end receives a quantum state to be processed from a quantum channel, wherein the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained by utilizing a quantum invisible state transfer protocol technology based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system; determining characteristic information of the quantum channel based on a system quantum state of the quantum system;
constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy;
determining the quantum parameter type to be measured;
and based on the constructed denoising strategy, quantum measurement is carried out on the quantum state to be processed after denoising treatment by using quantum measurement equipment matched with the quantum parameter type, so as to obtain a measurement result aiming at the target unknown quantum state.
2. The method of claim 1, wherein quantum measuring the denoised quantum state to be processed by using a quantum measurement device matched with the quantum parameter type to obtain a measurement result for the target unknown quantum state, comprises:
determining observables matching the quantum parameter type;
and applying the observable matched with the quantum parameter type to the quantum state to be processed after the denoising processing to obtain a measurement result aiming at the target unknown quantum state.
3. The method of claim 1, wherein the system quantum state is an entangled state, or a separable state.
4. The method of claim 1, wherein the quantum system comprises at least two qubits, at least one qubit in the quantum system being at the receiving end; the receiving end can perform local quantum operation on local qubits to implement the quantum channel.
5. The method of claim 4, wherein at least one qubit in the quantum system is located at the sender, the sender being capable of performing local quantum operations on local qubits to implement the quantum channel.
6. A quantum state measuring device is applied to a receiving end and comprises:
the receiving unit is used for receiving a quantum state to be processed from a quantum channel, wherein the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained by utilizing a quantum invisible state transfer protocol technology based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system;
a computing unit for determining characteristic information of the quantum channel based on a system quantum state of the quantum system;
the de-noising unit is used for constructing a de-noising strategy based on the characteristic information and de-noising the quantum state to be processed based on the constructed de-noising strategy;
the type determining unit is used for determining the type of the quantum parameter to be measured;
and the measurement unit is used for carrying out quantum measurement on the quantum state to be processed after the denoising treatment by using quantum measurement equipment matched with the quantum parameter type based on the constructed denoising strategy so as to obtain a measurement result aiming at the target unknown quantum state.
7. The apparatus of claim 6, wherein the measurement unit is further configured to determine observables matching the quantum parameter type; and applying the observable matched with the quantum parameter type to the quantum state to be processed after the denoising processing to obtain a measurement result aiming at the target unknown quantum state.
8. The apparatus of claim 6, wherein the system quantum state is an entangled state, or a separable state.
9. The apparatus of claim 6, wherein the quantum system comprises at least two qubits, at least one qubit in the quantum system being at the receiving end; the receiving end can perform local quantum operation on local qubits to implement the quantum channel.
10. The apparatus of claim 9, wherein at least one qubit in the quantum system is located at the sender, and the sender is capable of performing local quantum operations on local qubits to implement the quantum channel.
11. An electronic device, comprising:
at least one processor; and
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-5.
12. A non-transitory computer readable storage medium having stored thereon computer instructions for causing a computer to perform the method of any one of claims 1-5.
13. A quantum state measurement system comprises a receiving end and a transmitting end; wherein the content of the first and second substances,
the transmitting end is used for transmitting the quantum state to be processed through the quantum channel; the quantum state to be processed is a quantum state after a target unknown quantum state at a sending end is transmitted through the quantum channel; the quantum channel is obtained by utilizing a quantum invisible state transfer protocol technology based on a quantum system shared by a receiving end and a sending end, and the quantum channel is related to the system quantum state of the quantum system;
the receiving end is used for receiving the quantum state to be processed from the quantum channel; determining characteristic information of the quantum channel based on a system quantum state of the quantum system; constructing a denoising strategy based on the characteristic information, and denoising the quantum state to be processed based on the constructed denoising strategy; determining the quantum parameter type to be measured; and based on the constructed denoising strategy, quantum measurement is carried out on the quantum state to be processed after denoising treatment by using quantum measurement equipment matched with the quantum parameter type, so as to obtain a measurement result aiming at the target unknown quantum state.
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