Quantum key distribution system synchronization method and device

Abstract

The invention provides a quantum key distribution system synchronization method and device, and relates to the technical field of quantum communication, and the method comprises the steps: a detection node transmits a first synchronization signal and a second synchronization signal to a first node and a second node at the same time, so that the first node receives the first synchronization signal and transmits a third synchronization signal, the second node receives the second synchronization information and transmits a fourth synchronization signal; the detection node responds to a third synchronization signal from the first node and transmits a fifth synchronization signal to the second node, so that the second node receives fifth synchronization information and transmits a first quantum signal; the detection node responds to a fourth synchronization signal from the second node and transmits a sixth synchronization signal to the first node, so that the first node receives the sixth synchronization signal and transmits a second quantum signal; the detection node simultaneously receives a first quantum signal from the second node and a second quantum signal from the first node.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum communication technology, and more specifically, to a quantum key distribution system synchronization method and device. Background Art

[0002] Measurement-device-independent protocols, that is, all users act as senders to send quantum states to untrusted intermediate user nodes, and the intermediate user nodes jointly measure the quantum states and publish the measurement results. Quantum key distribution protocols in which users generate keys based on the measurement results and their own local preparation records, for example, measurement-device-independent quantum key distribution; twin-field quantum key distribution; mode-pairing quantum key distribution. Since the quantum states of multiple users need to be measured simultaneously, such protocols have high requirements for time synchronization.

[0003] The synchronization schemes in the current related technologies have the following technical problems: lack of effective scalability in a multi-user network environment, making it difficult to adapt to the needs of building large-scale quantum networks; when applied to mobile devices, the difficulty of time synchronization increases, resulting in insufficient stability of time synchronization, affecting the accuracy of time synchronization. Summary of the invention

[0004] In view of this, the present disclosure provides a quantum key distribution system synchronization method and device.

[0005] One aspect of the present disclosure provides a synchronization method for a quantum key distribution system, comprising: a detection node simultaneously transmits a first synchronization signal and a second synchronization signal to a first node and a second node respectively, so that the first node receives the first synchronization signal and transmits a third synchronization signal, so that the second node receives the second synchronization information and transmits a fourth synchronization signal; the detection node responds to the third synchronization signal from the first node and transmits a fifth synchronization signal to the second node, so that the second node receives the fifth synchronization information and transmits a first quantum signal; the detection node responds to the fourth synchronization signal from the second node and transmits a sixth synchronization signal to the first node, so that the first node receives the sixth synchronization signal and transmits a second quantum signal; the detection node simultaneously receives the first quantum signal from the second node and the second quantum signal from the first node; wherein the detection node is connected to the first node via a first channel; the detection node is connected to the second node via a second channel; the sum of the optical paths of the first synchronization signal, the third synchronization signal, the fifth synchronization signal and the first quantum signal is 2L A +2L B The sum of the optical paths of the second synchronization signal, the fourth synchronization signal, the sixth synchronization signal and the second quantum signal is 2L A +2L B Among them, L A is the optical path length of the first channel, L B is the optical path of the second channel mentioned above.

[0006] According to an embodiment of the present disclosure, the method further includes: the first quantum signal and the second quantum signal interfere with each other at the detection node to complete communication.

[0007] According to an embodiment of the present disclosure, the above-mentioned detection node simultaneously transmits the first synchronization signal and the second synchronization signal to the first node and the second node respectively, including: the above-mentioned detection node simultaneously transmits the above-mentioned first synchronization signal and the above-mentioned second synchronization signal through the above-mentioned first channel and the above-mentioned second channel respectively, so that the above-mentioned first node separates the above-mentioned first synchronization signal from the above-mentioned first channel, and the above-mentioned second node separates the above-mentioned second synchronization signal from the above-mentioned second channel.

[0008] According to an embodiment of the present disclosure, the detection node transmits the fifth synchronization signal to the second node in response to the third synchronization signal from the first node, including: the detection node separates the third synchronization signal from the first channel, transmits the fifth synchronization signal through the second channel, so that the second node separates the fifth synchronization signal from the second channel, and couples the first quantum signal into the second channel.

[0009] According to an embodiment of the present disclosure, the above-mentioned detection node transmits the sixth synchronization signal to the above-mentioned first node in response to the above-mentioned fourth synchronization signal from the above-mentioned second node, including: the above-mentioned detection node separates the above-mentioned fourth synchronization signal from the above-mentioned second channel, transmits the above-mentioned sixth synchronization signal through the above-mentioned first channel, so that the above-mentioned first node separates the above-mentioned sixth synchronization signal from the above-mentioned first channel, and couples the above-mentioned second quantum signal into the above-mentioned first channel.

[0010] According to an embodiment of the present disclosure, the detection node separates the first quantum signal from the second channel; and separates the second quantum signal from the first channel.

[0011] Another aspect of the present disclosure provides a device for the above-mentioned quantum key distribution system synchronization method, including: a detection node, a first node and a second node.

[0012] The above-mentioned detection node includes: a first laser, used for transmitting a first synchronization signal to the above-mentioned first node, so that the above-mentioned first node responds to the above-mentioned first synchronization signal and transmits a third synchronization signal; a second laser, used for transmitting a second synchronization signal to the above-mentioned second node, so that the above-mentioned second node responds to the above-mentioned second synchronization signal and transmits a fourth synchronization signal; a first quantum signal detector, used for receiving the first quantum signal from the above-mentioned second node; and a second quantum signal detector, used for receiving the second quantum signal from the above-mentioned first node; the above-mentioned detection node receives the above-mentioned third synchronization signal from the above-mentioned first node, and transmits a fifth synchronization signal to the above-mentioned second node; the above-mentioned detection node receives the above-mentioned fourth synchronization signal from the above-mentioned second node, and transmits a sixth synchronization signal to the above-mentioned first node.

[0013] The above-mentioned first node includes: a first photodetector, used for receiving the above-mentioned sixth synchronization signal from the above-mentioned detection node and generating a first trigger signal; and a third laser, used for responding to the above-mentioned first trigger signal and transmitting the above-mentioned second quantum signal to the above-mentioned detection node.

[0014] The second node includes: a second photodetector for receiving the fifth synchronization signal from the detection node and generating a second trigger signal; and a fourth laser for responding to the second trigger signal and transmitting the first quantum signal to the detection node.

[0015] According to an embodiment of the present disclosure, the above-mentioned first node also includes a first reflection device for receiving the above-mentioned first synchronization signal from the above-mentioned detection node, and reflecting and outputting the above-mentioned third synchronization signal; the above-mentioned second node also includes a second reflection device for receiving the above-mentioned second synchronization signal from the above-mentioned detection node, and reflecting and outputting the above-mentioned fourth synchronization signal.

[0016] According to an embodiment of the present disclosure, the above-mentioned detection node also includes: a third photodetector, used to receive the above-mentioned third synchronization signal and generate a third trigger signal; a fifth laser, used to respond to the above-mentioned third trigger signal and transmit the above-mentioned fifth synchronization signal to the above-mentioned second node; a fourth photodetector, used to receive the above-mentioned fourth synchronization signal and generate a fourth trigger signal; and a sixth laser, used to respond to the above-mentioned fourth trigger signal and transmit the above-mentioned sixth synchronization signal to the above-mentioned first node.

[0017] According to an embodiment of the present disclosure, the above-mentioned first node also includes: a fifth photodetector, used to receive the above-mentioned first synchronization signal from the above-mentioned detection node and generate a fifth trigger signal; and a seventh laser, used to respond to the above-mentioned fifth trigger signal and transmit the above-mentioned third synchronization signal to the above-mentioned detection node; the above-mentioned second node also includes: a sixth photodetector, used to receive the above-mentioned second synchronization signal from the above-mentioned detection node and generate a fifth trigger signal; and an eighth laser, used to respond to the above-mentioned fifth trigger signal and transmit the above-mentioned fourth synchronization signal to the above-mentioned detection node.

[0018] According to the embodiments of the present disclosure, the characteristic that different communication nodes have a constant total optical path of the transmission signal is utilized so that the quantum signals from different communication nodes can reach the detection node at the same time. The detection node, the first node and the second node are constructed into a closed-loop bidirectional synchronous signal transmission network through the first channel and the second channel, achieving an efficient and stable time synchronization effect, so that in a multi-user network environment, it still has good scalability and flexibility, and is suitable for the construction of a large-scale, high-precision quantum network. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0020] Figure 1 The following schematically shows an operation flow chart of a method for synchronizing a quantum key distribution system according to an embodiment of the present disclosure;

[0021] Figure 2 A schematic diagram of a quantum key distribution system synchronization device according to an embodiment of the present disclosure is schematically shown;

[0022] Figure 3 A schematic diagram schematically shows a quantum key distribution system synchronization device according to another embodiment of the present disclosure; and

[0023] Figure 4 A schematic diagram of a quantum key distribution system synchronization device according to another embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] With the development of social informatization, people have a higher demand for information security. At present, the security of the classical cryptographic system depends on the complexity of calculation. However, with the development of quantum computing, this classical encryption method will no longer be safe. Quantum key distribution (QKD) technology provides a method to establish unconditional security keys between communicators. Combined with "one-time one-pad", it can theoretically achieve unconditional security of information. In particular, the introduction of measurement device-independent protocols has promoted the practical application of quantum key distribution.

[0029] After more than 30 years of development, quantum key distribution technology has become very mature. However, the smooth implementation of measurement device-independent protocols is highly dependent on accurate quantum state interference. This requires that the quantum states emitted by the user need to arrive at the receiving end as simultaneously as possible, which places extremely stringent requirements on the accuracy of time synchronization. The accuracy of time synchronization is directly related to the accurate identification and decoding of quantum states. Any slight time deviation may introduce bit errors and reduce the key generation rate.

[0030] In the related technologies, a variety of solutions for free space time synchronization have been proposed, but they still have some key problems in practical applications:

[0031] On the one hand, in a multi-user network environment, achieving global time synchronization is a difficult problem. Existing solutions often lack effective scalability and flexibility, and are difficult to adapt to the needs of building large-scale quantum networks;

[0032] On the other hand, in mobile devices (such as vehicles, aircraft, ships, etc.), the time it takes for the light pulse to arrive at the detection end is in dynamic change, which brings great difficulties to time synchronization. Existing solutions may lead to insufficient stability of time synchronization and affect the accuracy of time synchronization.

[0033] The present invention provides a quantum key distribution system synchronization method and device, in order to effectively solve the above technical problems.

[0034] Figure 1 The operational flow chart of the quantum key distribution system synchronization method according to an embodiment of the present disclosure is schematically shown.

[0035] like Figure 1 As shown, the quantum key distribution system synchronization method includes operations S110 to S140.

[0036] In operation S110, the detection node transmits a first synchronization signal and a second synchronization signal to the first node and the second node respectively at the same time, so that the first node receives the first synchronization signal and transmits a third synchronization signal, so that the second node receives the second synchronization signal and transmits a fourth synchronization signal.

[0037] In operation S120, the detection node transmits a fifth synchronization signal to the second node in response to the third synchronization signal from the first node, so that the second node receives the fifth synchronization signal and transmits the first quantum signal.

[0038] In operation S130, the detection node transmits a sixth synchronization signal to the first node in response to the fourth synchronization signal from the second node, so that the first node receives the sixth synchronization signal and transmits a second quantum signal.

[0039] In operation S140, the detection node simultaneously receives the first quantum signal from the second node and the second quantum signal from the first node.

[0040] It should be noted that operation S120 and operation S130 do not limit the operation order.

[0041] According to an embodiment of the present disclosure, the detection node is connected to the first node through the first channel; the detection node is connected to the second node through the second channel; the sum of the optical paths of the first synchronization signal, the third synchronization signal, the fifth synchronization signal and the first quantum signal is 2L A +2L B The sum of the optical paths of the second synchronization signal, the fourth synchronization signal, the sixth synchronization signal and the second quantum signal is 2L A +2L B Among them, L A is the optical path length of the first channel, L B is the optical path of the second channel.

[0042] According to an embodiment of the present disclosure, the sum of the optical paths of the first synchronization signal, the third synchronization signal, the fifth synchronization signal, and the first quantum signal represents the total optical path of the transmission signal of the second node. The sum of the optical paths of the second synchronization signal, the fourth synchronization signal, the sixth synchronization signal, and the second quantum signal represents the total optical path of the transmission signal of the first node. The total optical path of the transmission signal of the first node is equal to the total optical path of the transmission signal of the second node, so that the detection node can simultaneously receive the first quantum signal and the second quantum signal after simultaneously transmitting the first synchronization signal and the second synchronization signal.

[0043] According to an embodiment of the present disclosure, when the detection node sends the first synchronization signal and the second synchronization signal at the same time, the speed of light is c, then the time taken for the first quantum signal and the second quantum signal to reach the detection node is the same as (2L A +2L B ) / c.

[0044] The present invention constructs a closed-loop bidirectional synchronous signal transmission network so that the first node and the second node, that is, different communication nodes, have a constant total optical path of the transmission signal, so that the detection node can simultaneously receive the first quantum signal and the second quantum signal after simultaneously transmitting the first synchronization signal and the second synchronization signal, so as to ensure that when the distances between different communication nodes are different, the respective quantum signals can be simultaneously delivered to the detection node without calibration, so as to achieve accurate synchronization of the quantum signals.

[0045] According to an embodiment of the present disclosure, the first quantum signal and the second quantum signal interfere at the detection node to complete the communication.

[0046] According to an embodiment of the present disclosure, the first quantum signal and the second quantum signal enter the detection node simultaneously and interfere at the detection node, so that the quantum state can be accurately identified and accurately decoded to complete the communication.

[0047] According to an embodiment of the present disclosure, the detection node transmits the first synchronization signal and the second synchronization signal through the first channel and the second channel respectively at the same time, so that the first node separates the first synchronization signal from the first channel and the second node separates the second synchronization signal from the second channel.

[0048] According to an embodiment of the present disclosure, the detection node uses wavelength division multiplexing technology to simultaneously transmit the first synchronization signal and the second synchronization signal through the first channel and the second channel respectively. The first node uses wavelength division multiplexing technology to separate the first synchronization signal from the first channel; the second node uses wavelength division multiplexing technology to separate the second synchronization signal from the second channel.

[0049] According to an embodiment of the present disclosure, the detection node separates the third synchronization signal from the first channel and transmits the fifth synchronization signal through the second channel, so that the second node separates the fifth synchronization signal from the second channel and couples the first quantum signal into the second channel.

[0050] According to an embodiment of the present disclosure, the detection node uses wavelength division multiplexing technology to separate the third synchronization signal from the first channel, and uses wavelength division multiplexing technology to transmit the fifth synchronization signal through the second channel, so that the second node uses wavelength division multiplexing technology to separate the fifth synchronization signal from the second channel, and uses wavelength division multiplexing technology to couple the first quantum signal into the second channel.

[0051] According to an embodiment of the present disclosure, the detection node separates the fourth synchronization signal from the second channel and transmits the sixth synchronization signal through the first channel, so that the first node separates the sixth synchronization signal from the first channel and couples the second quantum signal into the first channel.

[0052] According to an embodiment of the present disclosure, the detection node uses wavelength division multiplexing technology to separate the fourth synchronization signal from the second channel, and uses wavelength division multiplexing technology to transmit the sixth synchronization signal through the first channel, so that the first node uses wavelength division multiplexing technology to separate the sixth synchronization signal from the first channel, and uses wavelength division multiplexing technology to couple the second quantum signal into the first channel.

[0053] According to an embodiment of the present disclosure, the detection node separates the first quantum signal from the second channel; and separates the second quantum signal from the first channel.

[0054] According to an embodiment of the present disclosure, the detection node uses wavelength division multiplexing technology to separate the first quantum signal from the second channel; and uses wavelength division multiplexing technology to separate the second quantum signal from the first channel.

[0055] According to the embodiments of the present disclosure, different synchronization signals can be pressed into the same channel using wavelength division multiplexing technology, and quantum signals can be separated from the same channel. The use of wavelength division multiplexing technology can ensure that the first synchronization signal, the third synchronization signal, the sixth synchronization signal, and the second quantum signal all enter the first channel and are separated from the first channel; the use of wavelength division multiplexing technology can ensure that the second synchronization signal, the fourth synchronization signal, the fifth synchronization signal, and the first quantum signal all enter the second channel and are separated from the second channel. This makes the total optical path of the transmission signal of the first node and the total optical path of the transmission signal of the second node more stable, and increases the stability of the synchronization method of the quantum key distribution system.

[0056] Figure 2 A schematic diagram of a quantum key distribution system synchronization device according to an embodiment of the present disclosure is schematically shown.

[0057] like Figure 2 As shown, the device includes a detection node Charlie end, a first node Alice end and a second node Bob end.

[0058] According to an embodiment of the present disclosure, the detection node Charlie end includes: a first laser A1, used to transmit a first synchronization signal to the first node Alice end, so that the first node Alice end responds to the first synchronization signal and transmits a third synchronization signal; a second laser B1, used to transmit a second synchronization signal to the second node Bob end, so that the second node Bob end responds to the second synchronization signal and transmits a fourth synchronization signal; a first quantum signal detector 24, used to receive the first quantum signal from the second node Bob end; and a second quantum signal detector 14, used to receive the second quantum signal from the first node Alice end.

[0059] According to an embodiment of the present disclosure, the detection node Charlie receives the third synchronization signal from the first node Alice, and transmits the fifth synchronization signal to the second node Bob; the detection node Charlie receives the fourth synchronization signal from the second node Bob, and transmits the sixth synchronization signal to the first node Alice.

[0060] According to an embodiment of the present disclosure, the first node Alice includes: a first photodetector 13, which is used to receive the sixth synchronization signal from the detection node Charlie and generate a first trigger signal; and a third laser A Q , used to respond to the first trigger signal and transmit a second quantum signal to the detection node Charlie end.

[0061] According to an embodiment of the present disclosure, the second node Bob includes: a second photodetector 23 for receiving a fifth synchronization signal from the detection node Charlie and generating a second trigger signal; and a fourth laser B Q , used to respond to the second trigger signal and transmit the first quantum signal to the detection node Charlie end.

[0062] like Figure 2 As shown, L A Represents the optical path of the first channel, and the first channel includes a first end 11 of the first channel and a second end 12 of the first channel. The detection node Charlie injects the first synchronization signal and the sixth synchronization signal into the first channel from the first end 11 of the first channel as laser signals of different wavelength bands; the first node Alice separates the first synchronization signal and the sixth synchronization signal from the second end 12 of the first channel according to the different wavelength bands of the laser signal. The first node Alice injects the third synchronization signal and the first quantum signal into the first channel from the second end 12 of the first channel as laser signals of different wavelength bands, and the detection node Charlie separates the third synchronization signal and the first quantum signal from the first end 11 of the first channel according to the different wavelength bands of the laser signal.

[0063] like Figure 2 As shown, L B Represents the optical path of the second channel, and the second channel includes a first end 21 of the second channel and a second end 22 of the second channel. The detection node Charlie injects the second synchronization signal and the fifth synchronization signal into the second channel from the first end 21 of the second channel as laser signals of different wavelengths; the second node Bob separates the second synchronization signal and the fifth synchronization signal from the second end 22 of the second channel according to the different wavelengths of the laser signal. The second node Bob injects the fourth synchronization signal and the second quantum signal into the second channel from the second end 22 of the second channel as laser signals of different wavelengths, and the detection node Charlie separates the fourth synchronization signal and the second quantum signal from the first end 21 of the second channel according to the different wavelengths of the laser signal.

[0064] like Figure 2 As shown in FIG. 1 , different signal line segment formats indicate that the laser signals belong to different wavelength bands. For example, the first quantum signal and the second quantum signal belong to laser signals of the same wavelength band, and the third laser A Q and the fourth laser B Q The signal emitted uses the same signal line segment format as the signal received by the first quantum signal detector 24 and the second quantum signal detector 14.

[0065] According to an embodiment of the present disclosure, the first end 11 of the first channel, the second end 12 of the first channel, the first end 21 of the second channel, and the second end 22 of the second channel may include a wavelength division multiplexer to combine or separate laser signals of different wavelength bands. The first end 11 of the first channel and the first end 21 of the second channel may include a circulator to separate laser signals of the same wavelength band. According to an embodiment of the present disclosure, before the detection node Charlie simultaneously transmits the first synchronization signal and the second synchronization signal to the first node Alice and the second node Bob, respectively, it also includes: initialization and configuration of the synchronization device of the quantum key distribution system.

[0066] According to the embodiment of the present disclosure, the hardware installation and debugging of the quantum key distribution system synchronization device is performed. Ensure that the first laser A1, the second laser B1, the first quantum signal detector 24 and the second quantum signal detector 14 are correctly installed at the detection node Charlie; ensure that the first photodetector 13 and the third laser A Q Correctly installed at the first node Alice end; ensure that the second photodetector 23 and the fourth laser B Q Correctly install it at the second node Bob. Perform basic function tests on each device, such as stable emission of each laser and sensitivity adjustment of each photodetector, to ensure that each device is in the best working condition.

[0067] According to an embodiment of the present disclosure, a network connection verification is performed on a synchronization device of a quantum key distribution system. The physical link between the detection node Charlie, the first node Alice, and the second node Bob is checked to ensure that the connection is normal, for example, the connectivity of the line and the attenuation of the signal.

[0068] According to an embodiment of the present disclosure, the quantum key distribution system synchronization device is executed as follows: Figure 1 The operation of the quantum key distribution system synchronization method shown in FIG. The detection node Charlie receives the third synchronization signal and transmits the fifth synchronization signal to the second node Bob through a direct optical fiber connection. The detection node Charlie receives the fourth synchronization signal and transmits the sixth synchronization signal to the first node Alice through a direct optical fiber connection.

[0069] According to an embodiment of the present disclosure, the detection node Charlie uses wavelength division multiplexing technology to separate the first quantum signal from the second channel; the detection node Charlie uses wavelength division multiplexing technology to separate the second quantum signal from the first channel. The first quantum signal from the second node Bob and the second quantum signal from the first node Alice interfere at the detection node Charlie.

[0070] According to an embodiment of the present disclosure, the detection node Charlie simultaneously receives a first quantum signal from a second node Bob and a second quantum signal from a first node Alice, performs interference measurement, and announces the measurement results to achieve time synchronization of the three user nodes.

[0071] like Figure 2 As shown, the first node Alice also includes a first reflection device 15 for receiving a first synchronization signal from the detection node Charlie and reflecting and outputting a third synchronization signal; the second node Bob also includes a second reflection device 25 for receiving a second synchronization signal from the detection node Charlie and reflecting and outputting a fourth synchronization signal.

[0072] According to an embodiment of the present disclosure, the hardware installation and debugging of the synchronization device of the quantum key distribution system also includes: ensuring that the first reflection device 15 is correctly installed at the first node Alice; ensuring that the second reflection device 25 is correctly installed at the second node Bob. The angles of each reflection device are calibrated to ensure that each device is in the best working state.

[0073] Figure 3 A schematic diagram of a quantum key distribution system synchronization device according to another embodiment of the present disclosure is schematically shown.

[0074] like Figure 3 As shown, the detection node Charlie end also includes: a third photodetector 16, used to receive a third synchronization signal and generate a third trigger signal; a fifth laser B2, used to respond to the third trigger signal and transmit a fifth synchronization signal to the second node Bob end; a fourth photodetector 26, used to receive a fourth synchronization signal and generate a fourth trigger signal; and a sixth laser A2, used to respond to the fourth trigger signal and transmit a sixth synchronization signal to the first node Alice end.

[0075] According to an embodiment of the present disclosure, the hardware installation and debugging of the synchronization device of the quantum key distribution system also includes: ensuring that the third photodetector 16, the fifth laser B2, the fourth photodetector 26 and the sixth laser A2 are correctly installed at the detection node Charlie. Perform basic function tests on each device, such as the stable emission of each laser and the sensitivity adjustment of each photodetector, to ensure that each device is in the best working state.

[0076] Figure 4 A schematic diagram of a quantum key distribution system synchronization device according to another embodiment of the present disclosure is schematically shown.

[0077] like Figure 4As shown, the first node Alice also includes: a fifth photodetector 17, used to receive the first synchronization signal from the detection node Charlie, and generate a fifth trigger signal; and a seventh laser A0, used to respond to the fifth trigger signal, and transmit a third synchronization signal to the detection node Charlie; the second node Bob also includes: a sixth photodetector 27, used to receive the second synchronization signal from the detection node Charlie, and generate a fifth trigger signal; and an eighth laser B0, used to respond to the fifth trigger signal, and transmit a fourth synchronization signal to the detection node Charlie.

[0078] According to the embodiment of the present disclosure, the hardware installation and debugging of the synchronization device of the quantum key distribution system also includes: ensuring that the fifth photodetector 17 and the seventh laser A0 are correctly installed at the first node Alice; ensuring that the sixth photodetector 27 and the eighth laser B0 are correctly installed at the second node Bob. Perform basic function tests on each device, such as the stable emission of each laser and the sensitivity adjustment of each photodetector, to ensure that each device is in the best working state.

[0079] It should be noted that the quantum key distribution system synchronization device part in the embodiment of the present disclosure corresponds to the quantum key distribution system synchronization method part in the embodiment of the present disclosure. The description of the quantum key distribution system synchronization device part specifically refers to the quantum key distribution system synchronization method part, which will not be repeated here.

[0080] According to the embodiments of the present disclosure, by constructing a closed-loop bidirectional synchronization signal transmission network, the total optical path of the synchronization signal and the quantum signal between different communication nodes is always equal, thereby achieving the effect of self-compensation of time synchronization. After the detection node simultaneously sends synchronization signals to different communication nodes, it can simultaneously receive quantum signals from different communication nodes, thereby achieving an efficient and stable interference effect.

[0081] The quantum key distribution system synchronization method provided by the present disclosure has the characteristics of no calibration, good scalability and flexibility, and can easily cope with the construction of quantum networks with multiple communication nodes and the communication needs of mobile devices. Each communication node can independently perform time calibration, and can achieve global synchronization coordination and optimization, which is convenient for building a large-scale, high-reliability quantum communication network.

[0082] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A quantum key distribution system synchronization method, characterized in that: include: The detection node transmits a first synchronization signal and a second synchronization signal to a first node and a second node respectively at the same time, so that the first node receives the first synchronization signal and transmits a third synchronization signal, so that the second node receives the second synchronization signal and transmits a fourth synchronization signal; The detection node transmits a fifth synchronization signal to the second node in response to the third synchronization signal from the first node, so that the second node receives the fifth synchronization signal and transmits a first quantum signal; the detection node transmits a sixth synchronization signal to the first node in response to the fourth synchronization signal from the second node, so that the first node receives the sixth synchronization signal and transmits a second quantum signal; The detection node simultaneously receives the first quantum signal from the second node and the second quantum signal from the first node; The detection node is connected to the first node through a first channel; the detection node is connected to the second node through a second channel; the sum of the optical paths of the first synchronization signal, the third synchronization signal, the fifth synchronization signal and the first quantum signal is 2L A +2L B The sum of the optical paths of the second synchronization signal, the fourth synchronization signal, the sixth synchronization signal and the second quantum signal is 2L A +2L B Among them, L A is the optical path length of the first channel, L B is the optical path length of the second channel.

2. The quantum key distribution system synchronization method according to claim 1, characterized in that: Also includes: The first quantum signal and the second quantum signal interfere at the detection node to complete communication.

3. The quantum key distribution system synchronization method according to claim 1, characterized in that: The detection node simultaneously transmitting a first synchronization signal and a second synchronization signal to the first node and the second node respectively comprises: The detection node transmits the first synchronization signal and the second synchronization signal through the first channel and the second channel respectively at the same time, so that the first node separates the first synchronization signal from the first channel, and the second node separates the second synchronization signal from the second channel.

4. The quantum key distribution system synchronization method according to claim 1, characterized in that: The detecting node transmitting a fifth synchronization signal to the second node in response to the third synchronization signal from the first node comprises: The detection node separates the third synchronization signal from the first channel and transmits the fifth synchronization signal through the second channel, so that the second node separates the fifth synchronization signal from the second channel and couples the first quantum signal into the second channel.

5. The quantum key distribution system synchronization method according to claim 1, characterized in that: The detecting node transmitting, in response to the fourth synchronization signal from the second node, a sixth synchronization signal to the first node comprises: The detection node separates the fourth synchronization signal from the second channel and transmits the sixth synchronization signal through the first channel, so that the first node separates the sixth synchronization signal from the first channel and couples the second quantum signal into the first channel.

6. The quantum key distribution system synchronization method according to claim 1, characterized in that: include: The detection node separates the first quantum signal from the second channel; and separates the second quantum signal from the first channel.

7. A device for the quantum key distribution system synchronization method according to any one of claims 1 to 6, characterized in that: include: a detection node, a first node, and a second node; The detection node comprises: a first laser, configured to transmit a first synchronization signal to the first node, so that the first node responds to the first synchronization signal and transmits a third synchronization signal; a second laser, configured to transmit a second synchronization signal to the second node, so that the second node responds to the second synchronization signal and transmits a fourth synchronization signal; A first quantum signal detector, configured to receive a first quantum signal from the second node; and A second quantum signal detector, used to receive a second quantum signal from the first node; The detection node receives the third synchronization signal from the first node, and transmits a fifth synchronization signal to the second node; the detection node receives the fourth synchronization signal from the second node, and transmits a sixth synchronization signal to the first node; The first node comprises: a first photodetector, configured to receive the sixth synchronization signal from the detection node and generate a first trigger signal; and a third laser, configured to respond to the first trigger signal and transmit the second quantum signal to the detection node; The second node comprises: a second photodetector, configured to receive the fifth synchronization signal from the detection node and generate a second trigger signal; and A fourth laser is used to respond to the second trigger signal and transmit the first quantum signal to the detection node.

8. The device according to claim 7, characterized in that: The first node further comprises a first reflection device, configured to receive the first synchronization signal from the detection node and reflect and output the third synchronization signal; The second node also includes a second reflection device, which is used to receive the second synchronization signal from the detection node and reflect and output the fourth synchronization signal.

9. The device according to claim 7, characterized in that The detection node also includes: a third photodetector, configured to receive the third synchronization signal and generate a third trigger signal; a fifth laser, configured to respond to the third trigger signal and transmit the fifth synchronization signal to the second node; a fourth photodetector, configured to receive the fourth synchronization signal and generate a fourth trigger signal; and A sixth laser is used to respond to the fourth trigger signal and transmit the sixth synchronization signal to the first node.

10. The device according to claim 7, characterized in that: The first node also includes: a fifth photodetector, configured to receive the first synchronization signal from the detection node and generate a fifth trigger signal; and a seventh laser, configured to respond to the fifth trigger signal and transmit the third synchronization signal to the detection node; The second node also includes: a sixth photodetector, configured to receive the second synchronization signal from the detection node and generate a fifth trigger signal; and An eighth laser is used to respond to the fifth trigger signal and transmit the fourth synchronization signal to the detection node.

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