Double-field quantum key distribution system with stable phase
By introducing a signal measurement module and a phase modulator into the TF-QKD system, the phase drift of the optical signal is detected and compensated, solving the problem of drastic phase changes in long-distance transmission and achieving high-stability and high-efficiency key generation.
Patent Information
- Application Number
- CN202423287305.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Existing TF-QKD systems struggle to adapt to drastic phase changes during long-distance transmission, leading to decreased key generation efficiency and security.
The signal measurement module at the Charlie end detects the optical signals transmitted at the Alice and Bob ends, and triggers a phase modulator based on the detection results to compensate for the phase drift of the optical signal during transmission in the optical fiber, thereby achieving phase stabilization.
It achieves phase stability and high efficiency in long-distance transmission, adapts to drastic phase changes in complex environments, and ensures the efficiency and security of key generation.
Smart Images
Figure CN223613351U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to quantum information and optical communication technical field, concretely relates to a phase stable twin field quantum key distribution system. BACKGROUND
[0002] Twin-Field Quantum Key Distribution (TF-QKD) can achieve a key distribution rate beyond the limit of direct transmission without relay by using the coherent interference of two remote independent laser sources, even under long-distance conditions, which provides key technical support for building a global quantum secure communication network.
[0003] Traditional quantum key distribution systems such as BB84 protocol are mainly limited by quantum bit error rate and transmission distance, while the TF-QKD system greatly expands the distance range of key distribution by introducing additional light sources and complex phase correlation mechanisms. However, the TF-QKD system has very high requirements for phase stability, because any slight phase drift or noise can cause the destruction of quantum states, affecting the generation efficiency and security of the key.
[0004] The phase stability problem mainly comes from two aspects: one is external environmental factors such as temperature fluctuations, mechanical vibrations, etc., which can cause slight changes in the position of optical elements, and then affect the phase relationship in the optical path; the second is internal system factors, including frequency jitter of the laser, propagation time delay changes of the optical signal in the link, etc.
[0005] Therefore, in a complex and variable real environment, the existing TF-QKD system is difficult to adapt to the phase changes in long-distance transmission, resulting in the inability to guarantee the generation efficiency and security of the key. UTILITY MODEL CONTENTS
[0006] The utility model discloses in order to solve the problem that the existing TF-QKD system is difficult to adapt to the phase changes in long-distance transmission, proposes a phase stable twin field quantum key distribution system.
[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the utility model is as follows:
[0008] A phase stable twin field quantum key distribution system, comprising a Charlie end, an Alice end and a Bob end;
[0009] The Charlie end comprises a signal generation module, a signal measurement module and a phase modulator;
[0010] The different output ends of the signal generation module are respectively connected with the input end of the Alice end and the input end of the Bob end, the output end of the Alice end is connected with the input end of the signal measurement module, the output end of the Bob end is connected with the input end of the signal measurement module through the phase modulator, and the output end of the signal measurement module is connected with the input end of the phase modulator.
[0011] In the above scheme, the optical signals transmitted by the Alice end and the Bob end are detected by the signal measurement module of the Charlie end, and the phase modulator is triggered to compensate for the phase drift of the optical signals during transmission in the optical fiber according to the detection result, so that the phase is stabilized, which not only can adapt to the drastic change of the phase in long-distance transmission, but also can realize high stability and high efficiency in real deployment.
[0012] Preferably, the signal generation module comprises a first laser, a second laser, a first fan-in module and a first beam splitter.
[0013] The output end of the first laser and the output end of the second laser are respectively connected with the input end of the first beam splitter through the first fan-in module, and the different output ends of the first beam splitter are respectively connected with the input end of the Alice end and the input end of the Bob end.
[0014] Preferably, the first fan-in module and the first beam splitter are connected through a multi-core optical fiber.
[0015] Preferably, the signal generation module further comprises a first fan-out module and a second fan-out module.
[0016] The signal measurement module comprises a first detection module and a second detection module.
[0017] The output end of the Alice end is connected with the input end of the first detection module and the input end of the second detection module through the first fan-out module, and the output end of the Bob end is connected with the input end of the second fan-out module through the phase modulator, and the different output ends of the second fan-out module are respectively connected with the input end of the first detection module and the input end of the second detection module.
[0018] Preferably, the first detection module comprises a second beam splitter and a single-photon detector.
[0019] The different input ends of the second beam splitter are respectively connected with the output end of the first fan-out module and the output end of the second fan-out module, the output end of the second beam splitter is connected with the input end of the single-photon detector, and the output end of the single-photon detector is connected with the input end of the phase modulator.
[0020] Preferably, the second detection module comprises a third beam splitter and a signal detection unit.
[0021] Different input ends of the third beam splitter are connected with the output end of the first fan-out module and the output end of the second fan-out module respectively, and the output end of the third beam splitter is connected with the input end of the signal detection unit.
[0022] Preferably, the Alice end comprises a third fan-out module, a first phase-locked loop, a third laser, a fourth beam splitter, a first encoding module and a second fan-in module.
[0023] One output end of the first beam splitter is connected with one input end of the first phase-locked loop and one input end of the second fan-in module through the third fan-out module respectively, the output end of the first phase-locked loop is connected with the input end of the third laser, the output end of the third laser is connected with the other input end of the first phase-locked loop and the input end of the first encoding module through the fourth beam splitter respectively, the output end of the first encoding module is connected with the other input end of the second fan-in module, and the output end of the second fan-in module is connected with the input end of the first fan-out module.
[0024] Preferably, the Bob end comprises a fourth fan-out module, a second phase-locked loop, a fourth laser, a fifth beam splitter, a second encoding module and a third fan-in module.
[0025] The other output end of the first beam splitter is connected with one input end of the second phase-locked loop and one input end of the third fan-in module through the fourth fan-out module respectively, the output end of the second phase-locked loop is connected with the input end of the fourth laser, the output end of the fourth laser is connected with the other input end of the second phase-locked loop and the input end of the second encoding module through the fifth beam splitter respectively, the output end of the second encoding module is connected with the other input end of the third fan-in module, and the output end of the third fan-in module is connected with the input end of the second fan-out module through the phase modulator.
[0026] Preferably, the working wavelengths of the first laser and the second laser are the same.
[0027] Preferably, the first beam splitter is a 50:50 beam splitter.
[0028] The beneficial technical effects of the utility model are as follows:
[0029] The utility model provides a kind of phase-stable double field quantum key distribution system, and the optical signal of Alice end and Bob end transmission is detected by the signal measurement module of Charlie end, and according to detection result, phase modulator is triggered to compensate the phase drift of optical signal when transmitting in optical fiber, to realize phase stability, not only can adapt to phase violent change in long-distance transmission, also can realize high stability and high efficiency in real deployment. BRIEF DESCRIPTION OF DRAWINGS
[0030] Figure 1This is a schematic diagram of module connections according to one embodiment of the present invention;
[0031] Figure 2 This is a schematic diagram of module connections according to another embodiment of the present invention;
[0032] The components are as follows: 1. Charlie end; 11. Signal generation module; 111. First laser; 112. Second laser; 113. First fan-in module; 114. First beam splitter; 115. First fan-out module; 116. Second fan-out module; 12. Signal measurement module; 121. First detection module; 1211. Second beam splitter; 1212. Single-photon detector; 122. Second detection module; 1221. Third beam splitter; 1222. Signal detection unit; 13. Phase modulator; 2. Alice end; 21. Third fan-out module; 22. First phase-locked loop; 23. Third laser; 24. Fourth beam splitter; 25. First encoding module; 26. Second fan-in module; 3. Bob end; 31. Fourth fan-out module; 32. Second phase-locked loop; 33. Fourth laser; 34. Fifth beam splitter; 35. Second encoding module; 36. Third fan-in module. Detailed Implementation
[0033] To make the objectives, technical solutions and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments. However, the scope of protection of this utility model is not limited to the specific embodiments described below.
[0034] Example 1
[0035] A phase-stable dual-field quantum key distribution system includes Charlie terminal 1, Alice terminal 2 and Bob terminal 3;
[0036] The Charlie terminal 1 includes a signal generation module 11, a signal measurement module 12, and a phase modulator 13;
[0037] The different output terminals of the signal generation module 11 are respectively connected to the input terminals of Alice terminal 2 and Bob terminal 3. The output terminal of Alice terminal 2 is connected to the input terminal of the signal measurement module 12. The output terminal of Bob terminal 3 is connected to the input terminal of the signal measurement module 12 through the phase modulator 13. The output terminal of the signal measurement module 12 is connected to the input terminal of the phase modulator 13.
[0038] In the specific implementation process, the signal measurement module 12 of the Charlie terminal 1 detects the optical signals transmitted by the Alice terminal 2 and the Bob terminal 3, and triggers the phase modulator 13 to compensate for the phase drift of the optical signals during transmission in the optical fiber according to the detection result, so as to realize phase stabilization. Not only can it adapt to the drastic changes in phase in long-distance transmission, but also can realize high stability and high efficiency in real deployment.
[0039] Embodiment 2
[0040] A phase-stabilized double-field quantum key distribution system, comprising a Charlie terminal 1, an Alice terminal 2 and a Bob terminal 3.
[0041] The Charlie terminal 1 comprises a signal generation module 11, a signal measurement module 12 and a phase modulator 13.
[0042] More specifically, the signal generation module 11 comprises a first laser 111, a second laser 112, a first fan-in module 113 and a first beam splitter 114.
[0043] The output end of the first laser 111 and the output end of the second laser 112 are respectively connected to the input end of the first beam splitter 114 through the first fan-in module 113, and different output ends of the first beam splitter 114 are respectively connected to the input end of the Alice terminal 2 and the input end of the Bob terminal 3.
[0044] More specifically, the first fan-in module 113 and the first beam splitter 114 are connected through a multi-core optical fiber.
[0045] More specifically, the first laser 111 and the second laser 112 have the same operating wavelength.
[0046] More specifically, the first beam splitter 114 is a 50:50 beam splitter.
[0047] In the specific implementation process, the first laser 111 and the second laser 112 emit optical signals with the same wavelength, which are coupled into the multi-core optical fiber through the first fan-in module 113 for transmission, and the two optical signals are transmitted in different fiber cores; then the first beam splitter 114 divides them into two optical signals with the same intensity, one of which is transmitted to the Alice terminal 2 and the other is transmitted to the Bob terminal 3.
[0048] More specifically, the signal generation module 11 further comprises a first fan-out module 115 and a second fan-out module 116.
[0049] The signal measurement module 12 comprises a first detection module 121 and a second detection module 122.
[0050] The output end of the Alice end 2 is connected with the input end of the first detection module 121 and the input end of the second detection module 122 respectively through the first fan-out module 115; the output end of the Bob end 3 is connected with the input end of the second fan-out module 116 through the phase modulator 13, and different output ends of the second fan-out module 116 are connected with the input end of the first detection module 121 and the input end of the second detection module 122 respectively.
[0051] More specifically, the first detection module 121 comprises a second beam splitter 1211 and a single photon detector 1212.
[0052] Different input ends of the second beam splitter 1211 are connected with the output end of the first fan-out module 115 and the output end of the second fan-out module 116 respectively, the output end of the second beam splitter 1211 is connected with the input end of the single photon detector 1212, and the output end of the single photon detector 1212 is connected with the input end of the phase modulator 13.
[0053] More specifically, the second detection module 122 comprises a third beam splitter 1221 and a signal detection unit 1222.
[0054] Different input ends of the third beam splitter 1221 are connected with the output end of the first fan-out module 115 and the output end of the second fan-out module 116 respectively, and the output end of the third beam splitter 1221 is connected with the input end of the signal detection unit 1222.
[0055] In the specific implementation process, the optical signal transmitted from the Alice end 2 back to the Charlie end 1 is demultiplexed by the first fan-out module 115, one of the obtained beams (optical signal without encoding) is transmitted to the second beam splitter 1211, and the other beam (optical signal with encoding) is transmitted to the third beam splitter 1221.
[0056] The optical signal transmitted from the Bob end 3 back to the Charlie end 1 is demultiplexed by the second fan-out module 116, one of the obtained beams (optical signal without encoding) is transmitted to the second beam splitter 1211, and the other beam (optical signal with encoding) is transmitted to the third beam splitter 1221.
[0057] The two optical signals without encoding interfere at the second beam splitter 1211, the detection result is detected by the single photon detector 1212, the drift amount is fed back to the phase modulator 13, the phase compensation is performed on the optical signal transmitted from the Bob end 3 back to the Charlie end 1 through the phase modulator 13, the phase drift of the optical signal with encoding during the transmission in the optical fiber can be compensated, so that the phase can be adapted to the severe change in long-distance transmission, and the phase stability is realized.
[0058] More specifically, the Alice end 2 comprises a third fan-out module 21, a first phase-locked loop 22, a third laser 23, a fourth beam splitter 24, a first encoding module 25 and a second fan-in module 26;
[0059] One output end of the first beam splitter 114 is connected with one input end of the first phase-locked loop 22 and one input end of the second fan-in module 26 through the third fan-out module 21 respectively, the output end of the first phase-locked loop 22 is connected with the input end of the third laser 23, the output end of the third laser 23 is connected with another input end of the first phase-locked loop 22 and the input end of the first encoding module 25 through the fourth beam splitter 24 respectively, the output end of the first encoding module 25 is connected with another input end of the second fan-in module 26, and the output end of the second fan-in module 26 is connected with the input end of the first fan-out module 115.
[0060] More specifically, the Bob end 3 comprises a fourth fan-out module 31, a second phase-locked loop 32, a fourth laser 33, a fifth beam splitter 34, a second encoding module 35 and a third fan-in module 36;
[0061] Another output end of the first beam splitter 114 is connected with one input end of the second phase-locked loop 32 and one input end of the third fan-in module 36 through the fourth fan-out module 31 respectively, the output end of the second phase-locked loop 32 is connected with the input end of the fourth laser 33, the output end of the fourth laser 33 is connected with another input end of the second phase-locked loop 32 and the input end of the second encoding module 35 through the fifth beam splitter 34 respectively, the output end of the second encoding module 35 is connected with another input end of the third fan-in module 36, and the output end of the third fan-in module 36 is connected with the input end of the second fan-out module 116 through the phase modulator 13.
[0062] In the specific implementation, the optical signal transmitted from the Charlie end 1 to the Alice end 2 (the Bob end 3) is first demultiplexed through the third fan-out module 21 (the fourth fan-out module 31), one of the obtained optical signals is phase-locked through the light emitted by the first phase-locked loop 22 (the second phase-locked loop 32) and the third laser 23 (the fourth laser 33), and the other is directly transmitted to the second fan-in module 26 (the third fan-in module 36); the phase-locked optical signal is encoded in the first encoding module 25 (the second encoding module 35), and then multiplexed in the second fan-in module 26 (the third fan-in module 36). Among them, the encoding module is a phase encoding module.
[0063] According to the disclosure and teaching of the above description, the skilled in the art of the present application can also change and modify the above embodiments. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present application should fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience and do not constitute any limitation on the present application.
Claims
1. A phase-stable dual-field quantum key distribution system, characterized by, The Charlie end, the Alice end and the Bob end are included; The Charlie end includes a signal generation module, a signal measurement module and a phase modulator; Different output ends of the signal generation module are connected with input ends of the Alice end and the Bob end respectively, an output end of the Alice end is connected with an input end of the signal measurement module, an output end of the Bob end is connected with an input end of the signal measurement module through the phase modulator, and an output end of the signal measurement module is connected with an input end of the phase modulator.
2. The phase-stable dual-field quantum key distribution system of claim 1, wherein, The signal generation module includes a first laser, a second laser, a first fan-in module and a first beam splitter; Output ends of the first laser and the second laser are connected with an input end of the first beam splitter through the first fan-in module respectively, and different output ends of the first beam splitter are connected with input ends of the Alice end and the Bob end respectively.
3. The phase-stable dual-field quantum key distribution system of claim 2, wherein, The first fan-in module and the first beam splitter are connected through a multi-core optical fiber.
4. The phase-stable dual-field quantum key distribution system according to claim 1 or 2, characterized in that, The signal generation module further includes a first fan-out module and a second fan-out module; The signal measurement module includes a first detection module and a second detection module; An output end of the Alice end is connected with input ends of the first detection module and the second detection module through the first fan-out module respectively, and an output end of the Bob end is connected with an input end of the second fan-out module through the phase modulator, and different output ends of the second fan-out module are connected with input ends of the first detection module and the second detection module respectively.
5. The phase-stabilized two-field quantum key distribution system of claim 4, wherein, The first detection module includes a second beam splitter and a single-photon detector; Different input ends of the second beam splitter are connected with output ends of the first fan-out module and the second fan-out module respectively, an output end of the second beam splitter is connected with an input end of the single-photon detector, and an output end of the single-photon detector is connected with an input end of the phase modulator.
6. The phase-stable dual-field quantum key distribution system of claim 4, wherein, The second detection module includes a third beam splitter and a signal detection unit; Different input ends of the third beam splitter are connected with output ends of the first fan-out module and the second fan-out module respectively, and an output end of the third beam splitter is connected with an input end of the signal detection unit.
7. The phase-stabilized two-field quantum key distribution system of claim 2, wherein, The Alice end includes a third fan-out module, a first phase-locked loop, a third laser, a fourth beam splitter, a first encoding module and a second fan-in module; One output end of the first beam splitter is connected with one input end of the first phase-locked loop and one input end of the second fan-in module through the third fan-out module respectively, an output end of the first phase-locked loop is connected with an input end of the third laser, an output end of the third laser is connected with another input end of the first phase-locked loop and an input end of the first encoding module through the fourth beam splitter respectively, an output end of the first encoding module is connected with another input end of the second fan-in module, and an output end of the second fan-in module is connected with an input end of the first fan-out module.
8. The phase-stable dual-field quantum key distribution system of claim 2, wherein, The Bob end includes a fourth fan-out module, a second phase-locked loop, a fourth laser, a fifth beam splitter, a second encoding module and a third fan-in module; Another output end of the first beam splitter is connected with one input end of a second phase-locked loop and one input end of a third fan-in module through a fourth fan-out module, an output end of the second phase-locked loop is connected with an input end of a fourth laser, an output end of the fourth laser is connected with another input end of the second phase-locked loop and an input end of a second encoding module through a fifth beam splitter, an output end of the second encoding module is connected with another input end of the third fan-in module, and an output end of the third fan-in module is connected with an input end of the second fan-out module through a phase modulator.
9. The phase-stabilized two-field quantum key distribution system of claim 2, wherein, The first laser and the second laser have the same working wavelength.
10. The phase-stable dual-field quantum key distribution system of claim 2, wherein, The first beam splitter is a 50:50 beam splitter.