CN108737083B

CN108737083B - Quantum key distribution system, method and equipment

Info

Publication number: CN108737083B
Application number: CN201710272174.7A
Authority: CN
Inventors: 陆亮亮; 梁文烨
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-04-24
Filing date: 2017-04-24
Publication date: 2021-01-12
Anticipated expiration: 2037-04-24
Also published as: CN108737083A

Abstract

A quantum key distribution system, method and apparatus is provided that facilitates reducing the complexity and cost of quantum key distribution. The quantum key distribution system comprises a first communication device, a second communication device, a third party system, a first measuring device and a second measuring device; the first measuring device is used for generating a first receiving response after determining that the receiving position and the receiving time of the first photon sent by the first communication device and the receiving position and the receiving time of the third photon sent by the third-party system meet the preset mode, and the second measuring device is used for generating a second receiving response after determining that the receiving position and the receiving time of the second photon sent by the second communication device and the receiving position and the receiving time of the fourth photon sent by the third-party system meet the preset mode; and after receiving the first receiving response and the second receiving response, the first communication device and the second communication device respectively determine a bit value according to the phase of the photon, and store the determined bit value as a shared quantum key.

Description

Quantum key distribution system, method and equipment

Technical Field

The present application relates to the field of communications technologies, and in particular, to a system, a method, and an apparatus for quantum key distribution.

Background

With the development of computer and network technologies, the importance of communication security is increasing day by day. For example, when a user sends an input account and password to an internet banking system through a client during a communication process, the account and password are stolen and heard by a third party, which may cause property loss of the user.

The quantum key distribution technology encrypts information in the communication process through the generated shared random key between the two communication parties, so that the information of the two communication parties is kept secret in the communication process. However, the existing quantum key distribution system in the prior art is based on the BB84 protocol, in the BB84 protocol, the quantum signal source used for transmitting the key is a single-photon source, and the key information to be transmitted is encoded in the polarization state (or polarization direction) of a single photon. However, due to the manufacturing defects of the standard communication fiber and the influence of the surrounding environment, photons are affected by random birefringence when being transmitted in the fiber, so that the polarization state of the photons at the receiving end is disordered and disordered, and the polarization state of the photons at the receiving end needs to be corrected, which needs an accurate correction algorithm and device, so that the implementation is complex and the cost is high.

Disclosure of Invention

The application provides a quantum key distribution system, a method and equipment, which are beneficial to reducing the complexity of quantum key distribution and reducing the cost in specific implementation.

In a first aspect, an embodiment of the present application provides a quantum key distribution system, including: the system comprises a first communication device, a second communication device, a third party system, a first measuring device and a second measuring device; wherein the first communication device is configured to transmit the first photons to the first measurement device; the second communication device is used for sending the second photon to the second measuring device; the third party system is used for sending a third photon to the first measuring device and sending a fourth photon to the second measuring device; the first measuring device is used for receiving the first photon and the third photon, and generating a first receiving response after determining that the receiving position and the receiving time of the first photon and the receiving position and the receiving time of the third photon meet a preset mode; the second measuring device is used for receiving the second photon and the fourth photon, and generating a second receiving response after determining that the receiving position and the receiving time of the second photon and the receiving position and the receiving time of the fourth photon meet a preset mode; the first communication device is further configured to determine a first bit value according to the phase of the first photon and a preset rule after acquiring the first receiving response and the second receiving response, and store the first bit value as a shared quantum key between the first communication device and the second communication device; the second communication device is further configured to determine a second bit value according to the phase of the second photon and a preset rule after obtaining the first receiving response and the second receiving response, and store the second bit value as a shared quantum key between the first communication device and the second communication device, where the first bit value is the same as the second bit value.

In the embodiment of the application, since the shared quantum key is determined according to the phase of the photon, compared with the prior art, a single photon source is not required to be limited and the control of the measurement equipment on the polarization state of the photon is simplified, so that the complexity of quantum key distribution is reduced when the measurement equipment is specifically implemented, and the cost is reduced.

Based on the first aspect, in a possible implementation manner, after obtaining the first receiving response and the second receiving response, the first communication device notifies the second communication device of a phase set to which a phase of the first photon belongs and a phase set to which a phase of the second photon belongs, and determines the first bit value according to the phase of the first photon and a preset rule when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same; after the second communication device obtains the first receiving response and the second receiving response, the first communication device is informed of a phase set to which the phase of the second photon belongs and a phase set to which the phase of the first photon belongs, and when the phase set to which the phase of the second photon belongs and the phase set to which the phase of the first photon belongs are the same, the second communication device determines a second bit value according to the phase of the second photon and a preset rule.

By the method, the first communication device and the second communication device can determine that the first photon and the second photon belong to the same phase set, so that the accuracy of quantum key distribution is improved.

Based on the first aspect, in one possible design, the first communication device and the second communication device may determine the first bit value in the following manner:

the first communication equipment determines a bit value corresponding to the phase of the first photon according to the phase of the first photon and a corresponding relation between the pre-configured phase and the bit value; when the phase of the first photon belongs to the first phase set, the first communication equipment determines that a bit value corresponding to the phase of the first photon is a first bit value, and when the phase of the first photon belongs to the second phase set, the determined bit value corresponding to the phase of the first photon is overturned to obtain the first bit value; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; and the second communication equipment determines the bit value corresponding to the phase of the second photon to be the second bit value according to the corresponding relation of the phase and the bit value according to the phase of the second photon.

Since the first communication device and the second communication device can determine the bit value based on the corresponding relationship between the phase of the photon and the bit value, the method for determining the bit value is simplified, and the complexity of quantum key distribution is reduced.

Based on the first aspect, in one possible design, the third-party system includes a third-party device configured to send a third photon to the first measurement device and send a fourth photon to the second measurement device, where the third photon and the fourth photon form a photon pair entangled with each other.

In one possible design according to the first aspect, the first communication device includes a first coherent light source, a first unequal arm interferometer including two arms of unequal length, and a first phase modulator located on one of the arms of the first unequal arm interferometer;

the first coherent light source is used for generating first initial photons; the first unequal arm interferometer is used for modulating the phase of first initial photons through the first phase modulator to obtain first photons when the first initial photons are received through an arm provided with the first phase modulator, and sending the first photons to the first measuring equipment; when the first initial photon is received through the arm without the first phase modulator, the first initial photon is taken as a first photon, and the first photon is sent to the first measuring device;

the second communication device comprises a second coherent light source, a second unequal arm interferometer comprising two arms of unequal length, and a second phase modulator located on one of the arms of the second unequal arm interferometer;

the second coherent light source is used for generating second initial photons; the second unequal arm interferometer is used for modulating the phase of the second initial photon through the second phase modulator to obtain a second photon and sending the second photon to the second measuring equipment when receiving the second initial photon through the arm provided with the second phase modulator; when the second initial photon is received through the arm without the second phase modulator, the second initial photon is taken as a second photon, and the second photon is sent to the second measuring device;

the third party device comprises a time box entanglement source and an optical beam splitter, wherein the time box entanglement source is used for generating temporally entangled photon pairs; the time difference of the photons passing through the long arm and the short arm of the first unequal-arm interferometer corresponds to the time difference of the photons passing through the long arm and the short arm of the second unequal-arm interferometer is the same as the time difference of two different moments generating photon pairs; the optical beam splitter is used for splitting the received photon pair, sending a third photon in the photon pair to the first measuring device, and sending a fourth photon in the photon pair to the second measuring device.

In one possible design based on the first aspect, the third-party system includes a first third-party device, a second third-party device, and a third measurement device; the first third-party device is used for generating a first photon pair, sending a third photon in the first photon pair to the first measuring device, and sending a fifth photon in the first photon pair to the third measuring device; the second third-party device is used for generating a second photon pair, sending a fourth photon in the second photon pair to the second measuring device, and sending a sixth photon in the second photon pair to the third measuring device; the third measuring device is used for receiving the fifth photon and the sixth photon, and generating a third receiving response after determining that the receiving position and the receiving time of the fifth photon and the receiving position and the receiving time of the sixth photon meet a preset mode; after the first communication device obtains the first receiving response, the second receiving response and the third receiving response, determining a first bit value according to the phase of the first photon and a preset rule; and after the second communication device obtains the first receiving response, the second receiving response and the third receiving response, determining a second bit value according to the phase of the second photon and a preset rule.

According to the first aspect. In one possible design, the first communication device and the second communication device may obtain the first reception response and the second reception response respectively in the following manners:

when the first measuring device sends a first receiving response to the first communication device and the second communication device, and the second measuring device sends a second receiving response to the first communication device and the second communication device, the first communication device obtains the first receiving response and the second receiving response by receiving the first receiving response sent by the first measuring device and receiving the second receiving response sent by the second measuring device, and the second communication device obtains the first receiving response and the second receiving response by receiving the first receiving response sent by the first measuring device and receiving the second receiving response sent by the second measuring device; when first measurement equipment sends a first receiving response to first communication equipment and second measurement equipment sends a second receiving response to second communication equipment, the first communication equipment obtains the first receiving response and the second receiving response by receiving the first receiving response sent by the first measurement equipment and the second receiving response sent by the second communication equipment, wherein the first communication equipment sends the first receiving response to the second communication equipment after receiving the first receiving response, the second communication equipment obtains the first receiving response and the second receiving response by receiving the second receiving response sent by the second measurement equipment and the first receiving response sent by the first communication equipment, and the second communication equipment sends the second receiving response to the first communication equipment after receiving the second receiving response; when the first measurement device sends a first receiving response to the first communication device and the second measurement device sends a second receiving response to the first communication device, the first communication device obtains the first receiving response and the second receiving response by receiving the first receiving response sent by the first measurement device and the second receiving response sent by the second measurement device, wherein the first communication device sends the first receiving response and the second receiving response to the second communication device after receiving the first receiving response and the second receiving response, and the second communication device obtains the first receiving response and the second receiving response by receiving the first receiving response and the second receiving response sent by the first communication device.

Since the first measurement device, the second measurement device, the first communication device, and the second communication device may communicate with each other through the communication network, no matter to which communication device the first measurement device or the second measurement device sends the reception response, the communication devices may acquire the reception response through the communication network, which is not limited herein.

Based on the first aspect, in one possible design, the first measurement device includes a two-in two-out first optical beam splitter and two first detectors; two input ends of the first optical beam splitter are respectively connected with the first communication equipment and the third party system, and two output ends of the first optical beam splitter are respectively connected with the two first detectors; the second measuring device comprises a second optical beam splitter with two inlets and two outlets and two second detectors, two input ends of the second optical beam splitter are respectively connected with the second communication device and the third party system, and two output ends of the second optical beam splitter are respectively connected with the two second detectors;

the preset mode is that one detector of two detectors included in the measuring equipment respectively receives one photon at two different moments, wherein the time difference of the two different moments is the time difference generated when the photon passes through two arms with unequal arm interferometer lengths included in the communication equipment.

Specifically, the first measurement device generates a first reception response when determining that a first photon and a third photon are received by one of the two first detectors at two different times, wherein a time difference between the two different times is a time difference generated when the photons pass through two arms with unequal lengths; the second measurement device generates a second receive response upon determining that the second photon and the fourth photon were received by one of the two second detectors at two different times, wherein the time difference at the two different times is the time difference that would result if the photon passed through two arms of unequal length.

Based on the first aspect, in one possible design, the first communication device and the second communication device are respectively a terminal device.

In a second aspect, an embodiment of the present application provides a quantum key distribution method, including:

the first communication device sends the first photons to the first measurement device; after a first receiving response and a second receiving response are obtained, a first bit value is determined according to the phase of the first photon and a preset rule, and the first bit value is stored as a shared quantum key between the first communication device and the second communication device;

the first receiving response is generated by the first measuring device after the receiving position and the receiving time of the first photon are determined, and the receiving position and the receiving time of the third photon meet the preset mode, the second receiving response is generated by the second measuring device after the receiving position and the receiving time of the second photon and the receiving position and the receiving time of the fourth photon meet the preset mode are determined, the second photon is sent to the second measuring device by the second communication device, the third photon is sent to the first measuring device by the third party system, and the fourth photon is sent to the second measuring device by the third party system.

Based on the second aspect, in a possible design, after acquiring the first receiving response and the second receiving response, the first communication device notifies the second communication device of a phase set to which the phase of the first photon belongs and a phase set to which the phase of the second photon belongs, and determines the first bit value based on a preset rule according to the phase of the first photon when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same.

Based on the second aspect, in one possible design, the first communication device determines a bit value corresponding to the phase of the first photon according to the phase of the first photon and a preset correspondence relationship between the phase and the bit value; when the phase of the first photon belongs to the first phase set, determining a bit value corresponding to the phase of the first photon as a first bit value, and when the phase of the first photon belongs to the second phase set, turning over the determined bit value corresponding to the phase of the first photon to obtain the first bit value; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; or the first communication device determines the bit value corresponding to the phase of the first photon to be the first bit value according to the corresponding relation between the phase and the bit value according to the phase of the first photon.

Based on the second aspect, in one possible design, the third-party system includes a third-party device, the third photon is sent from the third-party device to the first measurement device, the fourth photon is sent from the third-party device to the second measurement device, and the third photon and the fourth photon form a photon pair entangled with each other.

Based on the second aspect, in one possible design, the third party system includes a first third party device, a second third party device, and a third measurement device;

the first communication device determines a first bit value according to the phase and a preset rule of the first photon after acquiring a first receiving response, a second receiving response and a third receiving response, wherein the third receiving response is generated by the third measurement device after determining that the receiving position and the receiving time of a fifth photon and the receiving position and the receiving time of a sixth photon meet a preset mode, the third photon is sent to the first measurement device by the first third party device, the fifth photon is sent to the third measurement device by the first third party device, the second third party device is sent to the second measurement device during the fourth photon, and the sixth photon is sent to the third measurement device by the second third party device.

In a possible design based on the second aspect, the first communication device may obtain the first receive response and the second receive response based on:

the first communication device acquires a first receiving response and a second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second measuring device; or the first communication device acquires the first receiving response and the second receiving response by receiving the first receiving response sent by the first measurement device and the second receiving response sent by the second communication device; or the first communication device acquires the first receiving response and the second receiving response by receiving the first receiving response and the second receiving response sent by the second communication device.

In addition, when the first communication device acquires the first reception response and the second reception response by receiving the first reception response sent by the first measurement device and the second reception response sent by the second communication device, the first communication device sends the second reception response to the second communication device after receiving the first reception response sent by the first measurement device.

Based on the second aspect, in one possible design, the preset mode is that one of the two detectors included in the measurement device receives one photon at two different time instants, and the time difference between the two time instants is a time difference generated when the photon passes through two arms with unequal lengths of the unequal arm interferometer included in the communication device.

In a third aspect, a communication device is provided, including: the system comprises a sending module, a receiving module and a processing module, wherein the sending module is used for sending first photons to first measuring equipment; the receiving module is used for acquiring a first receiving response and a second receiving response; the processing module is used for determining a first bit value according to the phase of the first photon and a preset rule after the receiving module obtains the first receiving response and the second receiving response, and storing the first bit value as a shared quantum key between the communication equipment and another communication equipment; the first receiving response is generated by the first measuring device after the receiving position and the receiving time of the first photon are determined, and the receiving position and the receiving time of the third photon meet the preset mode, the second receiving response is generated by the second measuring device after the receiving position and the receiving time of the second photon and the receiving position and the receiving time of the fourth photon meet the preset mode are determined, the second photon is sent to the second measuring device by another communication device, the third photon is sent to the first measuring device by a third system, and the fourth photon is sent to the second measuring device by the third system.

Based on the third aspect, in a possible design, after determining that the receiving module obtains the first receiving response and the second receiving response, the processing module triggers the sending module to notify another communication device of a phase set to which a phase of the first photon belongs, and triggers the receiving module to obtain a phase set to which a phase of the second photon belongs, and when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same, determines the first bit value according to the phase of the first photon and a preset rule.

Based on the third aspect, in a possible design, the processing module determines, according to the phase of the first photon and according to a pre-configured correspondence between the phase and the bit value, a bit value corresponding to the phase of the first photon; when the phase of the first photon belongs to the first phase set, determining a bit value corresponding to the phase of the first photon as a first bit value, and when the phase of the first photon belongs to the second phase set, turning over the determined bit value corresponding to the phase of the first photon to obtain the first bit value; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; or determining the bit value corresponding to the phase of the first photon to be the first bit value according to the corresponding relation between the phase and the bit value according to the phase of the first photon.

Based on the third aspect, in one possible design, the third party system includes a first third party device, a second third party device, and a third measurement device; the processing module determines a first bit value according to the phase and a preset rule of the first photon after determining that the receiving module obtains a first receiving response, a second receiving response and a third receiving response, wherein the third receiving response is generated after the third measuring device determines that the receiving position and the receiving time of a fifth photon and the receiving position and the receiving time of a sixth photon meet a preset mode, the third photon is sent to the first measuring device by the first third party device, the fifth photon is sent to the third measuring device by the first third party device, the fourth photon is sent to the second measuring device by the second third party device, and the sixth photon is sent to the third measuring device by the second third party device.

In one possible design based on the third aspect, the receiving module may obtain the first receive response and the second receive response based on:

the receiving module acquires a first receiving response and a second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second measuring device; or acquiring a first receiving response and a second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second communication device; or the first receiving response and the second receiving response are obtained by receiving the first receiving response and the second receiving response sent by the second communication device.

In addition, when the receiving module acquires the first receiving response and the second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second communication device, the processing module determines that the receiving module triggers the sending module to send the second receiving response to the second communication device after receiving the first receiving response sent by the first measuring device.

Based on the third aspect, in a possible design, the preset mode is that one of the two detectors included in the measurement device receives one photon at two different time instants, and the time difference between the two time instants is a time difference generated when the photon passes through two arms with unequal lengths of the unequal arm interferometer included in the communication device.

In a fourth aspect, an embodiment of the present application provides a communication device, including a transceiver, a processor, and a memory, where the transceiver is configured to receive and transmit signals, the memory is configured to store a software program and the like, and the processor is configured to read the software program and data stored in the memory and implement the method provided by the second aspect or any one of the implementation manners of the second aspect.

Drawings

Fig. 1 is a schematic diagram of a quantum key distribution system according to an embodiment of the present application;

fig. 2 is a schematic diagram of a quantum key distribution system according to an embodiment of the present application;

fig. 3 is a schematic diagram of a quantum key distribution system according to an embodiment of the present application;

fig. 4 is a schematic diagram of a quantum key distribution system according to an embodiment of the present application;

fig. 5 is a schematic diagram of a quantum key distribution system according to an embodiment of the present application;

fig. 6 is a schematic diagram of a quantum key distribution system according to an embodiment of the present application;

fig. 7 is a schematic flowchart of a quantum key distribution method according to an embodiment of the present application;

FIG. 8 is a schematic flow chart diagram illustrating a method for generating a response in accordance with an embodiment of the present application;

fig. 9a and 9b are schematic structural diagrams of a communication device according to an embodiment of the present application, respectively;

fig. 10a and 10b are schematic structural diagrams of a measurement device according to an embodiment of the present application, respectively.

Detailed Description

The present application will be described in further detail below with reference to the accompanying drawings.

As shown in fig. 1, a quantum key distribution system 100 according to an embodiment of the present application includes a first communication device 110, a second communication device 120, a third-party system 130, a first measurement device 140, and a second measurement device 150, where:

a first communication device 110 for transmitting first photons to a first measurement device 140;

a second communication device 120 for transmitting the second photons to a second measurement device 150;

a third party system 130 for sending a third photon to the first measurement device 140 and a fourth photon to the second measurement device 150;

the first measuring device 140 is configured to receive the first photon and the third photon, and generate a first receiving response after determining that the receiving position and the receiving time of the first photon and the receiving position and the receiving time of the third photon meet a preset mode;

it should be noted that the first measurement device 140 may not generate the first reception response when the reception position and the reception time of the first photon and the reception position and the reception time of the third photon do not satisfy the preset mode, or the first measurement device 140 may generate a response different from the first reception response when the reception position and the reception time of the first photon and the reception position and the reception time of the third photon do not satisfy the preset mode, for example, if the first reception response is indicated by bit 1, the generated reception response may be indicated by bit 0 when the reception position and the reception time of the first photon and the reception position and the reception time of the third photon do not satisfy the preset mode.

The second measuring device 150 is configured to receive the second photon and the fourth photon, and generate a second receiving response after determining that the receiving position and the receiving time of the second photon and the receiving position and the receiving time of the fourth photon meet a preset mode;

it should be noted that the second measurement device 150 may not generate the second reception response when the reception position and the reception time of the second photon and the reception position and the reception time of the fourth photon do not satisfy the preset mode, or the second measurement device 150 may generate a response different from the second reception response when the reception position and the reception time of the second photon and the reception position and the reception time of the fourth photon do not satisfy the preset mode, for example, if the second reception response is indicated by bit 1, the generated reception response may be indicated by bit 0 when the reception position and the reception time of the second photon and the reception position and the reception time of the fourth photon do not satisfy the preset mode.

The first communication device 110 is configured to determine a first bit value according to the phase of the first photon and a preset rule after acquiring the first receiving response and the second receiving response, and store the first bit value as a shared quantum key between the first communication device 110 and the second communication device 120;

the second communication device 120 is further configured to determine a second bit value according to the phase of the second photon and a preset rule after obtaining the first receiving response and the second receiving response, and store the second bit value as a shared quantum key between the first communication device 110 and the second communication device 120, where the first bit value is the same as the second bit value.

It should be noted that the first communication device 110 and the second communication device 120 may obtain the first reception response and the second reception response based on the following manners:

when the first measurement device 140 sends a first reception response to the first communication device 110, when the second measurement device 150 sends a second reception response to the second communication device 120, the first communication device 110 sends the first reception response to the second communication device 120 after receiving the first reception response, the second communication device 120 sends the second reception response to the first communication device 110 after receiving the second reception response, when the first communication device 110 receives the first reception response and the second reception response, the first bit value is determined according to the phase of the first photon and the preset rule, and when the second communication device 120 receives the first reception response and the second reception response, the second bit value is determined according to the phase of the second photon and the preset rule.

Furthermore, when the first measurement device 140 can also send a first reception response to the first communication device 110 and the second communication device 120, respectively, and the second measurement device 150 sends a second reception response to the first communication device 110 and the second communication device 120, respectively; or, the first measurement device 140 sends the first receive response to the second communication device 120, the second measurement device 150 sends the second receive response to the second communication device 120, and the second communication device 120 sends the first receive response and the second receive response to the first communication device 110 after receiving the first receive response and the second receive response; alternatively, the first measurement device 140 sends the first reception response to the first communication device 110, the second measurement device 150 sends the second reception response to the first communication device 110, and the first communication device 110 sends the first reception response and the second reception response to the second communication device 120 after receiving the first reception response and the second reception response. In the embodiment of the present application, the manner in which the first communication device 110 and the second communication device 120 receive the first reception response and the second reception response is not limited.

For example, the first communication device 110 and the second communication device 120 may determine the shared quantum key in the following manner:

the first communication device 110 determines a bit value corresponding to the phase of the first photon according to the phase of the first photon and a preset corresponding relationship between the phase and the bit value, determines that the bit value corresponding to the phase of the first photon is a first bit value when the phase of the first photon of the first communication device 110 belongs to a first phase set, and inverts the bit value corresponding to the phase of the determined first photon to obtain the first bit value when the phase of the first photon belongs to a second phase set, wherein the sum of any phase in the first phase set and the superposition sum of the phase per se are equal to a preset target value, the sum of the first phase in the second phase set and the second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; the second communication device 120 determines the bit value corresponding to the second photon as the second bit value according to the phase of the second photon and the correspondence between the phase and the bit value.

For example, the correspondence between the phases and the bit values arranged in advance is shown in table 1:

TABLE 1

Phase position	Bit value
		0	0
π	1
		π/2	0
3π/2	1

Wherein, assuming that the target value is 0 or 2 pi, the first phase set is {0, pi }; the second phase set is { pi/2, 3 pi/2 }, if the phase of the first photon is 0, the first bit value is 0, if the phase of the first photon is pi/2, the sum of the phase of the first photon and the phase of the second photon is a target value, and the phase set to which the phase of the first photon and the phase of the second photon belong is the same, because the bit value corresponding to pi/2 is 0 and 0 is 1 after being inverted, the first bit value is 1.

In order to ensure that the phase set to which the phase of the first photon belongs is the same as the phase set to which the phase of the second photon belongs, the first communication device 110 notifies the second communication device 120 of the phase set to which the phase of the first photon belongs after acquiring the first receiving response and the second receiving response, acquires the phase set to which the phase of the second photon belongs, and determines the first bit value according to the phase of the first photon and a preset rule when determining that the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same; after obtaining the first receiving response and the second receiving response, the second communication device 120 notifies the first communication device 110 of a phase set to which the phase of the second photon belongs, obtains a phase set to which the phase of the first photon belongs, and determines the second bit value according to the phase of the second photon and a preset rule when determining that the phase set to which the phase of the second photon belongs and the phase set to which the phase of the first photon belongs are the same.

The first communication device 110 notifies the second communication device 120 of the phase set to which the phase of the first photon belongs, which may be notified based on the following:

taking table 1 as an example, if the set of phases to which the phase of the first photon belongs is {0, pi }, the first indication information is sent to the second communication device, where the first indication information may be a bit value or a sequence, or the first indication information may be directly the set of phases {0, pi } to which the phase of the first photon belongs, which is not limited herein. When the set of phases to which the phase of the first photon belongs is { pi/2, 3 pi/2 }, sending second indication information to the second communication device, wherein the second indication information is different from the first indication information, if the first indication information is indicated by a bit value of 1, the second indication information may be indicated by a bit value of 0, or the first indication information is indicated by a first sequence, and the second indication information is indicated by a second sequence different from the first sequence, or the second indication information may be directly the set of phases { pi/2, 3 pi/2 } to which the phase of the first photon belongs, which is not limited herein. The second communication device may obtain the set of phases to which the phase of the first photon belongs in the following manner: and when the second communication equipment receives the second indication information, determining that the phase set to which the phase of the first photon belongs is {0, pi }, and when the second communication equipment receives the second indication information, determining that the phase set to which the phase of the first photon belongs is { pi/2, 3 pi/2 }. The way of the second communication device informing the first communication device of the phase set to which the phase of the second photon belongs is similar to the way of the first communication device informing the second communication device of the phase set to which the phase of the first photon belongs, and details are not repeated herein; the way in which the second communication device acquires the phase set to which the phase of the first photon belongs is similar to the way in which the first communication device acquires the phase set to which the phase of the second photon belongs, and details are not repeated here.

In addition, it should be noted that, as shown in fig. 2, the third-party system 130 includes a third-party device, wherein the third-party device transmits a third photon to the first measurement device 140, and transmits a fourth photon to the second measurement device 150, wherein the third photon and the fourth photon form a photon pair entangled with each other. Optionally, the third party system 130 is a third party device.

As shown in fig. 3, when the third party system 130 comprises a third party device, the first communication device 110 comprises a first coherent light source 1101, a first unequal arm interferometer 1102 and a first phase modulator 1103, wherein the first unequal arm interferometer 1102 comprises two arms of unequal length, the first phase modulator 1103 being located on one of the arms of the first unequal arm interferometer 1102;

a first coherent light source 1101 for generating first initial photons;

a first unequal arm interferometer 1102, configured to, when receiving a first initial photon through an arm provided with a first phase modulator 1103, modulate a phase of the first initial photon by the first phase modulator 1103 to obtain a first photon, and send the first photon to the first measurement device 140; upon receiving the first initial photon through the arm not provided with the first phase modulator 1103, the first initial photon is sent to the first measurement device 140 as a first photon.

The second communication device 120 comprises a second coherent light source 1201, a second unequal arm interferometer 1202, and a second phase modulator 1203, wherein the second unequal arm interferometer 1202 comprises two arms of unequal length, the second phase modulator 1203 being located on one arm of the second unequal arm interferometer 1202;

a second coherent light source 1201 for generating second initial photons;

a second unequal arm interferometer 1202, configured to, when a second initial photon is received by an arm provided with a second phase modulator 1203, modulate the phase of the second initial photon by the second phase modulator 1203 to obtain a second photon, and send the second photon to the second measurement device 150; upon receiving the second initial photon through the arm without the second phase modulator 1203 positioned, sending the second initial photon as a second photon to the second measurement device 150;

the third device includes a time box entanglement source 1301 and an optical beam splitter 1302;

the time box entanglement source 1301 is configured to generate a photon pair entangled with time, and send the photon pair to the optical splitter 1302, where a time difference corresponding to two different times of generating the photon pair is the same as a time difference of the photon passing through the long and short arms of the first unequal arm interferometer 1102, and a time difference of the photon passing through the long and short arms of the second unequal arm interferometer 1202;

and a beam splitter 1302, configured to split the received photon pair, send a third photon to the first measurement device 140, and send a fourth photon to the second measurement device 150.

Since the first phase modulator 1103 may be located on the short arm of the first unequal arm interferometer 1102 or on the long arm of the first unequal arm interferometer 1102, the second phase modulator 1203 may be located on the short arm of the second unequal arm interferometer 1202 or on the long arm of the second unequal arm interferometer 1202, no matter which arm of the unequal arm interferometer the phase modulator is located on, the implementation of the embodiment of the present application is not affected.

It should be understood that the first coherent light source and the second coherent light source may be lasers in the embodiments of the present application.

The following description will be given by taking an example in which the first phase modulator 1103 is located on the short arm of the first unequal arm interferometer 1102, and the second phase modulator 1203 is located on the short arm of the second unequal arm interferometer 1202.

Specifically, in the quantum key distribution system shown in fig. 3, the first phase modulator 1103 is located on the short arm of the first unequal-arm interferometer 1102, and the second phase modulator 1203 is located on the short arm of the second unequal-arm interferometer 1202, wherein the modulation phases of the first phase modulator 1103 and the second phase modulator 1203 are the same, and it is assumed that the modulation phases of the first phase modulator 1103 and the second phase modulator 1203 are 0, pi/2, and 3 pi/2, respectively, since the photon state of the first photon is 0, pi/2, and 3 pi/2

θ_aFor indicating the modulation phase of the first phase modulator 1103; the second photon has a photon state of

θ_bFor indicating the modulation phase of the second phase modulator 1203, the photon state function of the photon pair consisting of the third photon and the fourth photon is (| t)₂＞_s|t₂＞_i+|t₁＞_s|t₁＞_i) Wherein t is₁For indicating the time, t, at which a photon reaches the detector via the short arm₂For indicating the moment when a photon reaches the detector via the long arm, subscript a for a first photon, subscript b for a second photon, subscript s for a third photon, and subscript i for a fourth photon, and so onThis, the overall state function of the first photon, the second photon, and the photon pair may be expressed as a direct product of the photon states of the first communication device, the second communication device, and the third party device:

when the first measurement device 140 includes a two-in two-out first optical splitter BS1, a first detector D1 and a first detector D2, and the second measurement device 150 includes a two-in two-out second optical splitter BS2, a second detector D3 and a second detector D4, two input ends of the first optical splitter BS1 are respectively connected to the first communication device 110 and the third party device, two output ends of the first optical splitter BS1 are respectively connected to the first detector D1 and the first detector D2, two input ends of the second optical splitter BS2 are respectively connected to the second communication device 120 and the third party device, and two output ends of the second optical splitter BS2 are respectively connected to the second detector D3 and the second detector D4.

Since the detector usually cannot distinguish the number of photons, two-photon interference, i.e. two-photon double interference terms, i.e. events in which two photons arrive at the same detector at the same time, is ignored, and the photons received by the same detector in the first measurement device 140 at two times, the time difference between which is (t) and (t), are taken as successful detection response events, taking into account the evolution of the integral state function in the waveform passing through the first beam splitter BS1 and the second beam splitter BS2₂-t₁) Then, the quantum state corresponding to the successful detection response event is:

it should be noted that the first measurement device generating the first reception response and the second measurement device generating the second reception response include the following cases:

|D2,t₂＞|D2,t₁＞|D4,t₂＞|D4,t₁＞、|D2,t₂＞|D2,t₁＞|D3,t₂＞|D3,t₁＞、|D1,t₂＞|D1,t₁＞|D4,t₂＞|D4,t₁and | D1, t₂＞|D1,t₁＞|D3,t₂＞|D3,t₁＞；

Wherein, | D2, t₂For the case where the first detector D2 receives photons as they pass through the long arm; i D2, t₁For the first detector D2 when photons pass the short arm; i D4, t₂For the case where the second detector D4 receives photons as they pass through the long arm; i D4, t₁For the case where the second detector D4 receives photons through the short arm; i D1, t₂For the case where the first detector D1 receives photons as they pass through the long arm; i D1, t₁For the first detector D1 when photons pass the short arm; i D3, t₂For the case where the second detector D3 receives photons as they pass through the long arm; i D3, t₁Used to indicate the case where the second detector D3 receives photons as they pass through the short arm.

Thus, to enable the first detector D1 to be able to be at t, since the modulation phases of the first and second phase modulators are 0, π/2 and 3 π/2₁First photon is received at time t₂The third photon is received at a time instant, or the first detector D1 can be at t₁A third photon is received at time t₂The first photon is received at a time, or the first detector D2 can be at t₁First photon is received at time t₂The third photon is received at a time instant, or the first detector D2 can be at t₁A third photon is received at time t₂A first photon is received at a time instant, generating a first received response, and a second detector D3 is capable of being at t₁Receiving a second photon at time t₂The fourth photon is received at a time, or the second detector D3 can be at t₁Time of receiving a fourth photon, at t₂The second photon is received at a time, or the second detector D4 can be at t₁Receiving a second photon at time t₂The fourth photon is received at a time, or the second detector D4 can be at t₁Time of receiving a fourth photon, at t₂A second photon is received at a time to generate a second received response, theta_a+θ_b0 or 2 pi, can make

Not 0, e.g. when the first detector D1 is at t₁A third photon is received at time t₂Generating a first receiving response when the first photon is received at any time, if the phase of the first photon is theta_a0, the phase of the second photon is also θ_bAt 0, D3 at t₁Receiving a second photon at time t₂A second receive response is generated when a fourth photon is received.

Optionally, in this embodiment of the application, the preset mode is that one detector of two detectors included in the measurement apparatus receives one photon at two different times, respectively, where a time difference between the two different times is a time difference generated when the photon passes through two arms with unequal lengths.

In particular, the first measurement device 140 generates the first receive response upon determining that the first photon and the third photon are received by one of the two first detectors at two different times, wherein the time difference between the two different times is the time difference between when the photon passes through two arms of unequal length; the second measurement device 150 generates a second receive response upon determining that a second photon and a fourth photon were received by one of the two second detectors at two different times, wherein the time difference at the two different times is the time difference that would result if the photon passed through two arms of unequal length.

Taking the correspondence between the phase and the bit value shown in table 1 as an example, a specific process of determining the shared quantum key by the first communication device 110 and the second communication device 120 will be described. As shown in Table 2, the phase θ of the first photon_aAnd the phase θ of the second photon_bAnd the correspondence with bit values.

TABLE 2

Taking Table 2 as an example, when θ_aAnd theta_bBoth in the first set of phases {0, π }, the first communication device and the second communication device receive the first receive response and the second receive response simultaneously, if θ_aIf 0, the first communication device determines that the first bit value is 0 and the second communication device θ_bIf θ is 0, the second bit value determined by the second communication device is also 0, and thus 0 is the quantum shared key between the first communication device and the second communication device_aπ/2, then θ_bSince the bit value corresponding to pi/2 is 0 and the bit value corresponding to 3 pi/2 is 1, it is necessary to flip the bit value determined by one of the first communication device and the second communication device, so that the first bit value determined by the first communication device is the same as the second bit value determined by the second communication device, and it may be specifically specified in a preset rule which communication device of the first communication device and the second communication device performs bit value flipping, or the first communication device and the second communication device perform negotiation through a communication network to determine which communication device performs flipping, which is not limited herein.

It should be noted that the third photon may be a signal photon in a temporally entangled photon pair, the fourth photon may be an idle photon in the temporally entangled photon pair, and a laser and an unequal arm interferometer may be directly configured in a third device to generate a temporally entangled photon pair (also referred to as a pair of time-bin entangled photons).

For example, pairs of temporally entangled photons may be defined in advance by a time interval (e.g., (t)₂-t₁) Two laser pulses pumping a nonlinear crystal produce a photon pair that is temporally indistinguishable from either a previous or subsequent pump pulse, thereby producing a pair of photons that is temporally indistinguishable. Besides, a pair of time-bin entangled photons can be generated by systems such as quantum dots, diamond color centers and the like.

Specifically, in this embodiment of the present application, the first measurement device and the second measurement device may be a base station or other network devices, the first communication device and the second communication device may be terminal devices, such as a smart phone, a desktop computer, a tablet computer, a notebook computer, and the like, as shown in fig. 4, the first measurement device and the second measurement device are connected through a backbone network, the first communication device and the second communication device are located in respective local area networks, and when the first communication device and the second communication device communicate with each other, information may be directly encrypted by using a shared quantum key and then transmitted, thereby implementing secure communication. Therefore, on the premise of ensuring safe communication, the long-distance quantum key distribution of users in two different local area networks can be realized, the whole quantum key distribution process does not depend on whether the intermediate equipment is safe or not, only the respective sites of two communication parties are required to be safe and reliable, and the quantum key distribution method can be well applied to intercity quantum communication or a backbone network.

In addition, in an actual network, in order to also place the first communication device and the second communication device in a secure place, such as a machine room of an operator, in this embodiment of the present application, in consideration of the security of the first communication device and the second communication device, to implement a quantum key distribution process in a different local area network at a longer distance, the first communication device and the second communication device may be a base station or other network devices, such as the quantum key distribution system shown in fig. 5, and after the first communication device and the second communication device generate the shared quantum key, when the terminal device in the cell where the first communication device is located and the terminal device in the cell where the second communication device is located communicate, the shared quantum key is issued to the terminal device to encrypt information, so as to implement confidentiality of the communication process.

In addition, the technical solution of the quantum key distribution system shown in fig. 2 may be extended to the quantum key distribution system shown in fig. 6, where the quantum key distribution system shown in fig. 6 includes a first communication device, a second communication device, a first measurement device, a second measurement device, and a third system, and is different from the quantum key distribution system shown in fig. 2 in that the third system includes a first third-party device, a second third-party device, and a third measurement device; the first third-party device is used for generating a first photon pair, sending a third photon in the first photon pair to the first measuring device, and sending a fifth photon in the first photon pair to the third measuring device;

the second third-party device is used for generating a second photon pair, sending a fourth photon in the second photon pair to the second measuring device and sending a sixth photon in the second photon pair to the third measuring device;

the third measuring device is used for receiving the fifth photon and the sixth photon and generating a third receiving response after determining that the receiving position and the receiving time of the fifth photon and the receiving position and the receiving time of the sixth photon meet a preset mode;

the difference between the determination of the first bit value by the first communication device in fig. 2 is that the first communication device in fig. 6 determines the first bit value according to the phase of the first photon and a preset rule after acquiring the first receive response, the second receive response, and the third receive response;

the difference between the determination of the second bit value by the second communication device in fig. 2 is that the second communication device in fig. 6 determines the second bit value according to the phase of the second photon and the preset rule after acquiring the first receiving response, the second receiving response, and the third receiving response.

In addition, the specific distribution process of the quantum key shown in fig. 6, and the manner, preset mode, preset rule, etc. of obtaining the receiving response are similar to those of the quantum key system shown in fig. 2, and are not described in detail here.

It should be noted that the technical solution of the embodiment of the present application may also be extended to more third-party devices and measurement devices to implement quantum key distribution over a longer distance.

It should be further noted that the arrow directions in the quantum key communication systems shown in fig. 1 to 6 in the embodiments of the present application refer to transmission directions of photons, and mutual communication between the respective devices included in the quantum key communication systems shown in fig. 1 to 6 in the embodiments of the present application may be implemented through a communication network such as a local area network, a wide area network, and the like, so as to implement mutual communication between information (such as the first received response, the second received response, the third received response, the indication information, and the like).

Based on the same concept, a quantum key distribution method as shown in fig. 7 is further provided in the embodiment of the present application, and since a quantum key distribution system corresponding to the quantum key distribution method as shown in fig. 7 in the embodiment of the present application is the quantum key distribution system as shown in fig. 1 in the embodiment of the present application, for example, the implementation of the quantum key distribution method as shown in fig. 7 in the embodiment of the present application, reference may be made to the implementation of the quantum key distribution system as shown in fig. 1, and repeated details are not repeated.

As shown in fig. 7, an embodiment of the present application provides a quantum key distribution method, including:

step 700, a first communication device sends a first photon to a first measurement device;

step 710, after acquiring a first receiving response and a second receiving response, the first communication device determines a first bit value according to the phase of the first photon and a preset rule, and stores the first bit value as a shared quantum key between the first communication device and the second communication device;

In a possible design, after acquiring the first receiving response and the second receiving response, the first communication device notifies the second communication device of a phase set to which the phase of the first photon belongs and a phase set to which the phase of the second photon belongs, and determines the first bit value based on a preset rule according to the phase of the first photon when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same.

In one possible design, the first communication device determines a bit value corresponding to the phase of the first photon according to the phase of the first photon and a preset corresponding relationship between the phase and the bit value; when the phase of the first photon belongs to the first phase set, determining a bit value corresponding to the phase of the first photon as a first bit value, and when the phase of the first photon belongs to the second phase set, turning over the determined bit value corresponding to the phase of the first photon to obtain the first bit value; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; or the first communication device determines the bit value corresponding to the phase of the first photon to be the first bit value according to the corresponding relation between the phase and the bit value according to the phase of the first photon.

In one possible design, the third-party system includes a third-party device, the third photon is transmitted from the third-party device to the first measurement device, the fourth photon is transmitted from the third-party device to the second measurement device, and the third photon and the fourth photon form a photon pair entangled with each other.

In one possible design, the third party system includes a first third party device, a second third party device, and a third measurement device; the first communication device determines a first bit value according to the phase and a preset rule of the first photon after acquiring a first receiving response, a second receiving response and a third receiving response, wherein the third receiving response is generated by the third measurement device after determining that the receiving position and the receiving time of a fifth photon and the receiving position and the receiving time of a sixth photon meet a preset mode, the third photon is sent to the first measurement device by the first third party device, the fifth photon is sent to the third measurement device by the first third party device, the fourth photon is sent to the second measurement device by the second third party device, and the sixth photon is sent to the third measurement device by the second third party device.

In one possible design, the first communication device may obtain the first receive response and the second receive response based on:

In one possible design, the predetermined mode is that one of the two detectors included in the measurement device receives one photon at two different times, and the time difference between the two times is the time difference generated when the photon passes through two arms with unequal lengths of the unequal arm interferometer included in the communication device.

As shown in fig. 8, an embodiment of the present application provides a method for generating a response, including:

step 800, a measuring device receives a first photon and a second photon, wherein the first photon and the second photon come from two different devices respectively;

step 810, the measuring device generates a receiving response when determining that the receiving position and the receiving time of the first photon and the receiving position and the receiving time of the second photon meet a preset mode.

In one possible design, two detectors are included in the measurement device, and the measurement device generates a receive response upon determining that the first photon and the second photon were received by one of the two detectors at two different times, wherein no other photon was received by the detector between the two different times.

Based on the same concept, in the embodiment of the present application, a communication device as shown in fig. 9a and a measurement device as shown in fig. 10a are further provided, and since the quantum key distribution system corresponding to the communication device as shown in fig. 9a and the measurement device as shown in fig. 10a in the embodiment of the present application is the quantum key distribution system as shown in fig. 1 in the embodiment of the present application, the implementation of the communication device as shown in fig. 9a and the measurement device as shown in fig. 10a in the embodiment of the present application may refer to the implementation of the quantum key distribution system as shown in fig. 1, and repeated details are omitted.

As shown in fig. 9a, the communication device of the embodiment of the present application includes: a sending module 910a, a receiving module 920a, and a processing module 930a, wherein the sending module 910a is configured to send a first photon to a first measurement device; the receiving module 920a is configured to obtain a first receiving response and a second receiving response; the processing module 930a is configured to determine, after the receiving module obtains the first receiving response and the second receiving response, a first bit value according to a phase of the first photon and a preset rule, and store the first bit value as a shared quantum key between the communication device and another communication device; the first receiving response is generated by the first measuring device after the receiving position and the receiving time of the first photon are determined, and the receiving position and the receiving time of the third photon meet the preset mode, the second receiving response is generated by the second measuring device after the receiving position and the receiving time of the second photon and the receiving position and the receiving time of the fourth photon meet the preset mode are determined, the second photon is sent to the second measuring device by another communication device, the third photon is sent to the first measuring device by a third system, and the fourth photon is sent to the second measuring device by the third system.

In one possible design, after determining that the receiving module 920a receives the first receiving response and the second receiving response, the processing module 930a triggers the sending module 910a to notify another communication device of a phase set to which the phase of the first photon belongs, and triggers the receiving module 920a to obtain a phase set to which the phase of the second photon belongs, and determines the first bit value according to the phase of the first photon and a preset rule when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same.

In one possible design, the processing module 930a determines a bit value corresponding to the phase of the first photon according to the phase of the first photon and a preset corresponding relationship between the phase and the bit value; when the phase of the first photon belongs to the first phase set, determining a bit value corresponding to the phase of the first photon as a first bit value, and when the phase of the first photon belongs to the second phase set, turning over the determined bit value corresponding to the phase of the first photon to obtain the first bit value; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; or determining the bit value corresponding to the phase of the first photon to be the first bit value according to the corresponding relation between the phase and the bit value according to the phase of the first photon.

In one possible design, the third party system includes a first third party device, a second third party device, and a third measurement device; the processing module 930a determines the first bit value according to the phase of the first photon and a preset rule after determining that the receiving module 920a receives the first receiving response, the second receiving response and a third receiving response, wherein the third receiving response is generated after determining that the receiving position and the receiving time of a fifth photon and the receiving position and the receiving time of a sixth photon meet the preset mode by the third measuring device, the third photon is sent to the first measuring device by the first third party device, the fifth photon is sent to the third measuring device by the first third party device, the fourth photon is sent to the second measuring device by the second third party device, and the sixth photon is sent to the third measuring device by the second third party device.

In one possible design, the receiving module 920a may obtain the first receive response and the second receive response based on:

the receiving module 920a obtains a first receiving response and a second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second measuring device; or acquiring a first receiving response and a second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second communication device; or the first receiving response and the second receiving response are obtained by receiving the first receiving response and the second receiving response sent by the second communication device.

In addition, when the receiving module 920a obtains the first receiving response and the second receiving response by receiving the first receiving response sent by the first measuring device and the second receiving response sent by the second communication device, the processing module 930a determines that the receiving module 920a triggers the sending module 910a to send the second receiving response to the second communication device after receiving the first receiving response sent by the first measuring device.

It should be understood that, in the embodiment of the present application, the transmitting module and the receiving module may be implemented by a transceiver, where the transceiver includes a coherent light source, an unequal arm interferometer and a phase modulator, where the coherent light source is configured to generate an initial photon, and when the unequal arm interferometer receives the initial photon through an arm with the phase modulator, the unequal arm interferometer modulates a phase of the initial photon through the phase modulator to obtain a first photon, and transmits the first photon to the first measurement device; when the initial photon is received through the arm without the phase modulator, the initial photon is taken as a first photon, and the first photon is sent to the first measuring device; besides, the transceiver further includes a module for transceiving communication data (such as the first receive response, the second receive response, and the like), and optionally, the transceiver further includes other devices for processing photons, the processing module may be implemented by a processor, as shown in fig. 9b, a hardware structure diagram of the communication device 900b includes a processor 910b, a transceiver 920b, and a memory 930b, where the memory 930b is used to store a software program and communication data information and the like that are transceived by the transceiver 920b, and the processor 910b is used to read the software program stored in the memory 930b and the communication data information that is transceived by the transceiver 920b, so as to implement the quantum key distribution method shown in fig. 7 in this embodiment of the present application.

The processor 910b may be a general Central Processing Unit (CPU), a microprocessor, an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits, configured to perform related operations to implement the technical solution provided in the embodiment of the present Application.

It should be noted that although the communication device shown in fig. 9b only shows the processor 910b, the transceiver 920b and the memory 930b, in a specific implementation, it should be understood by those skilled in the art that the communication device also contains other components necessary for normal operation. Also, it will be apparent to those skilled in the art that the communication device may also contain hardware components that implement other additional functions, according to particular needs. Furthermore, it should be clear to a person skilled in the art that the communication device may also comprise only the components or modules necessary for implementing the embodiments of the present application, and not necessarily all of the components shown in fig. 9 b.

As shown in fig. 10a, the measurement apparatus according to the embodiment of the present application includes: a transceiver module 1000a and a processing module 1010a, wherein the transceiver module 1000a is configured to receive a first photon and a second photon, and the first photon and the second photon come from two different devices respectively; the processing module 1010a is configured to generate a receiving response when it is determined that the receiving position and the receiving time of the first photon and the receiving position and the receiving time of the second photon received by the transceiver module 1000a satisfy the preset mode.

In one possible implementation, the transceiver module 1000a includes two detectors, and the processing module 1010a generates a receive response when it determines that the first photon and the second photon are received by one of the two detectors at two different times, wherein the other photon is not received by the detector between the two different times.

It should be understood that in the embodiments of the present application, the transceiver module may be implemented by a transceiver, wherein the transceiver includes an optical beam splitter, two detectors, and the detectors are used for receiving photons; the optical splitter is used for interfering with photons transmitted from the device and then transmitting the photons to the detector, and the transceiver further includes a module for transceiving communication data (e.g., receiving a response, etc.) or includes other devices for processing the photons, the processing module may be implemented by a processor, as shown in a hardware structure diagram of the measurement device 1000b shown in fig. 10b, and includes a processor 1010b, a transceiver 1020b, and a memory 1030b, where the memory 1030b is used for storing a software program and communication data information and the like transceived by the transceiver 1020b, and the processor 1010b is used for reading the software program stored in the memory 1030b and the communication data information transceived by the transceiver 1020b, so as to implement the method for generating a response shown in fig. 8 in this embodiment of the present application.

The processor 1010b may be a general Central Processing Unit (CPU), a microprocessor, an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits, configured to execute related operations to implement the technical solution provided in the embodiment of the present Application.

It should be noted that although the measurement device shown in fig. 10b only shows the processor 1010b, the transceiver 1020b and the memory 1030b, in a specific implementation, it will be understood by those skilled in the art that the measurement device also contains other components necessary to achieve normal operation. Also, it will be apparent to those skilled in the art that the measuring device may also contain hardware components to implement other additional functions, according to particular needs. Furthermore, it should be clear to a person skilled in the art that the measuring device may also comprise only the components or modules necessary for implementing the embodiments of the application, and not necessarily all of the components shown in fig. 10 b.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While some possible embodiments of the present application have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including the embodiments of the application and all alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A quantum key distribution system, comprising: the system comprises a first communication device, a second communication device, a third party system, a first measuring device and a second measuring device;

the first communication device to transmit first photons to the first measurement device;

the second communication device is used for sending a second photon to the second measuring device;

the third party system is used for sending a third photon to the first measuring device and sending a fourth photon to the second measuring device;

the first measuring device is used for receiving the first photon and the third photon, and generating a first receiving response after determining that the receiving position and the receiving time of the first photon and the receiving position and the receiving time of the third photon meet a preset mode;

the second measuring device is used for receiving the second photon and the fourth photon, and generating a second receiving response after determining that the receiving position and the receiving time of the second photon and the receiving position and the receiving time of the fourth photon meet the preset mode;

the first communication device is further configured to determine a first bit value according to the phase of the first photon and a preset rule after the first receiving response and the second receiving response are obtained, and store the first bit value as a shared quantum key between the first communication device and the second communication device;

the second communication device is further configured to determine a second bit value according to the phase of the second photon and the preset rule after obtaining the first receiving response and the second receiving response, and store the second bit value as a shared quantum key between the first communication device and the second communication device, where the first bit value is the same as the second bit value;

the preset mode is that one detector of two detectors included in the measuring equipment respectively receives a photon at two different moments, and the time difference of the two moments is the time difference generated when the photon passes through two arms with unequal lengths of an unequal arm interferometer included in the communication equipment.

2. The quantum key distribution system according to claim 1, wherein after obtaining the first receive response and the second receive response, the first communication device determines a first bit value according to the phase of the first photon and a preset rule, and specifically includes:

after the first communication device obtains the first receiving response and the second receiving response, the second communication device is informed of a phase set to which the phase of the first photon belongs and a phase set to which the phase of the second photon belongs, and when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same, a first bit value is determined according to the phase of the first photon and a preset rule;

after the second communication device obtains the first receiving response and the second receiving response, determining a second bit value according to the phase of the second photon and the preset rule, specifically including:

after the second communication device obtains the first receiving response and the second receiving response, the first communication device is informed of a phase set to which the phase of the second photon belongs and obtains a phase set to which the phase of the first photon belongs, and when the phase set to which the phase of the second photon belongs and the phase set to which the phase of the first photon belongs are the same, a second bit value is determined according to the phase of the second photon and the preset rule.

3. The quantum key distribution system according to claim 1 or 2, wherein the determining, by the first communication device, the first bit value according to the phase of the first photon and the preset rule specifically comprises:

the first communication equipment determines a bit value corresponding to the phase of the first photon according to the phase of the first photon and a corresponding relation between a pre-configured phase and the bit value;

the first communication device determines a bit value corresponding to the phase of the first photon to be the first bit value when the phase of the first photon belongs to a first phase set, and turns over the determined bit value corresponding to the phase of the first photon to obtain the first bit value when the phase of the first photon belongs to a second phase set; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase;

the second communication device determines the second bit value according to the phase of the second photon and the preset rule, and specifically includes:

and the second communication equipment determines the bit value corresponding to the phase of the second photon as the second bit value according to the phase of the second photon and the corresponding relation between the phase and the bit value.

4. A quantum key distribution system as claimed in claim 1 or 2 wherein the third party system comprises a third party device for transmitting the third photon to the first measurement device and the fourth photon to the second measurement device, the third and fourth photons forming a mutually entangled photon pair.

5. The quantum key distribution system of claim 4, wherein the first communication device comprises a first coherent light source, a first unequal arm interferometer comprising two arms of unequal length, and a first phase modulator located on one of the arms of the first unequal arm interferometer;

the first coherent light source is used for generating first initial photons;

the first unequal-arm interferometer is used for modulating the phase of the first initial photon through the first phase modulator to obtain the first photon and sending the first photon to the first measuring device when the first initial photon is received through an arm provided with the first phase modulator; when the first initial photon is received by an arm without the first phase modulator, the first initial photon is taken as the first photon, and the first photon is sent to the first measuring equipment;

the second coherent light source is used for generating second initial photons;

the second unequal-arm interferometer is used for modulating the phase of the second initial photon through the second phase modulator to obtain the second photon when the second initial photon is received through the arm provided with the second phase modulator, and sending the second photon to the second measuring device; when the second initial photon is received by an arm without the second phase modulator, the second initial photon is taken as the second photon, and the second photon is sent to the second measuring equipment;

the third-party device comprises a time box entanglement source and an optical beam splitter, wherein the time box entanglement source is used for generating temporally entangled photon pairs and sending the photon pairs to the optical beam splitter; the time difference of the photons passing through the long arm and the short arm of the first unequal-arm interferometer corresponds to the time difference of the photons passing through the long arm and the short arm of the second unequal-arm interferometer is the same as the time difference of two different moments generating photon pairs;

and the optical beam splitter is used for splitting the received photon pair, sending a third photon in the photon pair to the first measuring device, and sending a fourth photon in the photon pair to the second measuring device.

6. A quantum key distribution system as claimed in claim 1 or 2 wherein the third party system comprises a first third party device, a second third party device and a third measurement device;

the first third-party device is configured to generate a first photon pair, send a third photon of the first photon pair to the first measurement device, and send a fifth photon of the first photon pair to the third measurement device;

the second third-party device is configured to generate a second photon pair, send a fourth photon of the second photon pair to the second measurement device, and send a sixth photon of the second photon pair to the third measurement device;

after the first communication device obtains the first receiving response and the second receiving response, determining a first bit value according to the phase of the first photon and the preset rule, specifically including:

after the first communication device obtains the first receiving response, the second receiving response and the third receiving response, determining a first bit value according to the phase of the first photon and the preset rule;

after the second communication device obtains the first receiving response and the second receiving response, determining the second bit value according to the phase of the second photon and the preset rule, specifically including:

and after the second communication device obtains the first receiving response, the second receiving response and the third receiving response, determining the second bit value according to the phase of the second photon and the preset rule.

7. The quantum key distribution system of claim 1 or 2, wherein the first measurement device is further to send the first receive response to the first communication device and the second communication device; the second measurement device is further configured to send the second receive response to the first communication device and a second communication device;

the acquiring, by the first communication device, the first reception response and the second reception response specifically includes:

the first communication device receives the first receiving response sent by the first measurement device and receives the second receiving response sent by the second measurement device;

the obtaining, by the second communication device, the first reception response and the second reception response specifically includes:

the second communication device receives the first receiving response sent by the first measuring device and receives the second receiving response sent by the second measuring device;

alternatively, the first and second electrodes may be,

the first measurement device is further configured to send the first receive response to the first communication device; the second measurement device is further configured to send the second receive response to the second communication device; the first communication device is further configured to send the first receiving response to the second communication device after the first receiving response is obtained; the second communication device is further configured to send the second receiving response to the first communication device after the second receiving response is obtained;

the first communication device receives the first receiving response sent by the first measurement device and receives the second receiving response sent by the second communication device;

the second communication equipment receives the second receiving response sent by the second measuring equipment and receives the first receiving response sent by the first communication equipment;

alternatively, the first and second electrodes may be,

the first measurement device is further configured to send the first receive response to the first communication device; the second measurement device is further configured to send the second receive response to the first communication device; after acquiring the first receiving response and the second receiving response, the first communication device sends the first receiving response and the second receiving response to the second communication device;

and the second communication equipment receives the first receiving response and the second receiving response sent by the first communication equipment.

8. A quantum key distribution system according to claim 1 or 2, wherein the first measurement device comprises a two-in two-out first optical beam splitter and two first detectors; two input ends of the first optical beam splitter are respectively connected with the first communication device and the third party system, and two output ends of the first optical beam splitter are respectively connected with two first detectors; the second measuring device comprises a second optical beam splitter with two inlets and two outlets and two second detectors, two input ends of the second optical beam splitter are respectively connected with the second communication device and the third party system, and two output ends of the second optical beam splitter are respectively connected with the two second detectors.

9. The quantum key distribution system of claim 1 or 2, wherein the first communication device and the second communication device are each a terminal device.

10. A quantum key distribution method, comprising:

the first communication device sends the first photons to the first measurement device;

after the first communication device obtains a first receiving response and a second receiving response, a first bit value is determined according to the phase of a first photon and a preset rule, and the first bit value is stored as a shared quantum key between the first communication device and the second communication device;

wherein the first receiving response is generated by the first measuring device after determining that the receiving position and the receiving time of the first photon and the receiving position and the receiving time of a third photon meet a preset mode, the second receiving response is generated by the second measuring device after determining that the receiving position and the receiving time of a second photon and the receiving position and the receiving time of a fourth photon meet the preset mode, the second photon is sent to the second measuring device by the second communicating device, the third photon is sent to the first measuring device by a third party system, and the fourth photon is sent to the second measuring device by the third party system; the first bit value is the same as a second bit value, the second bit value is determined according to the phase of the second photon and the preset rule after the second communication device obtains the first receiving response and the second receiving response, and the second bit value is a quantum key shared between the first communication device and the second communication device and stored by the second communication device;

11. The method according to claim 10, wherein the determining, by the first communication device, the first bit value according to the phase of the first photon and the preset rule after acquiring the first receive response and the second receive response specifically includes:

after the first receiving response and the second receiving response are obtained, the second communication device is informed of a phase set to which the phase of the first photon belongs and a phase set to which the phase of the second photon belongs, and when the phase set to which the phase of the first photon belongs and the phase set to which the phase of the second photon belongs are the same, a first bit value is determined according to the phase of the first photon and the preset rule.

12. The method according to claim 10 or 11, wherein the determining, by the first communications device, the first bit value according to the phase of the first photon and the preset rule specifically comprises:

the first communication device determines a bit value corresponding to the phase of the first photon to be the first bit value when the phase of the first photon belongs to a first phase set, and turns over the determined bit value corresponding to the phase of the first photon to obtain the first bit value when the phase of the first photon belongs to a second phase set; the sum of any phase in the first phase set and the superposition of the phase is equal to a preset target value, the sum of a first phase in the second phase set and a second phase is equal to the target value, the first phase is any phase in the second phase set, and the second phase is different from the first phase; alternatively, the first and second electrodes may be,

and the first communication equipment determines the bit value corresponding to the phase of the first photon to be the first bit value according to the phase of the first photon and the corresponding relation between the phase and the bit value.

13. The method of claim 10 or 11, wherein the third party system comprises a third party device, the third photon is transmitted by the third party device to the first measurement device, the fourth photon is transmitted by the third party device to the second measurement device, and the third photon and the fourth photon form a photon pair that is entangled with each other.

14. The method of claim 10 or 11, wherein the third party system comprises a first third party device, a second third party device, and a third measurement device;

after the first communication device obtains the first receiving response and the second receiving response, determining the first bit value according to the phase of the first photon and the preset rule, including:

after receiving the first receiving response, the second receiving response and a third receiving response, the first communication device determines the first bit value according to the phase of the first photon and the preset rule, wherein the third receiving response is generated after the third measurement device determines that the receiving position and the receiving time of a fifth photon and the receiving position and the receiving time of a sixth photon meet a preset mode, the third photon is sent to the first measurement device by the first third party device, the fifth photon is sent to the third measurement device by the first third party device, the fourth photon is sent to the second measurement device by the second third party device, and the sixth photon is sent to the third measurement device by the second third party device.

15. The method according to claim 10 or 11, wherein the acquiring, by the first communication device, the first reception response and the second reception response includes:

the first communication device receives the first receiving response sent by the first measurement device and receives the second receiving response sent by the second measurement device; alternatively, the first and second electrodes may be,

the first communication device receives the first receiving response and the second receiving response sent by the second communication device; alternatively, the first and second electrodes may be,

after receiving the first reception response sent by the first measurement device, the first communication device further includes:

the first communication device sends the first reception response to the second communication device.