Annular multi-user quantum key distribution system based on space division multiplexing

Abstract

The utility model discloses an annular multi-user quantum key distribution system based on space division multiplexing. The annular multi-user quantum key distribution system comprises a Charlie relay end, a plurality of user ends and an annular quantum channel, the Charlie relay end and the plurality of user ends are respectively accessed to the annular quantum channel; the Charlie relay end comprises a multi-wavelength pulse generation module, a fan-in module, a first beam splitter, a first fan-out module and a detection module. The utility model discloses an annular multi-user quantum key distribution system based on space division multiplexing, which is characterized in that a multi-wavelength pulse generation module emits pulses with multiple wavelengths, the pulses are coupled to a specified fiber core of a multi-core optical fiber through a fan-in module, and then the pulses reach specified user sides through an annular quantum channel; spatial division multiplexing is utilized to realize simultaneous communication of a plurality of user sides, so that the communication capacity is expanded, and the non-linear effect in the optical fiber is prevented from being increased. And meanwhile, a Sagnac ring structure is adopted, so that the phase stability is very good.

Description

TECHNICAL FIELD

[0001] The utility model relates to quantum information and optical communication technical field, concretely relates to a kind of ring-shaped multi-user quantum key distribution system based on space division multiplexing. BACKGROUND

[0002] Quantum key distribution (QKD) is the most mature quantum cryptography technology, which is a quantum technology allowing remote users to share encryption keys, and it follows the principles of quantum mechanics, including quantum non-cloning principle, Heisenberg uncertainty principle, etc., which theoretically guarantees absolute security.

[0003] In practice, due to the non-ideal characteristics of the device, there are security vulnerabilities, and there is a possibility of exploiting vulnerabilities by eavesdroppers. Therefore, in order to ensure the actual security of the QKD system, the QKD protocol and related theories have been followed. The twin-field quantum key distribution (TF-QKD) protocol inherits the advantage of immune to probe-end attacks of the measurement-device-independent protocol, and breaks the traditional key rate-distance limit. However, the original TF-QKD protocol does not have a perfect security proof, and the sending or not-sending twin-field quantum key distribution (SNS-TF-QKD) protocol proposed on this basis has a strict security proof. Researchers have conducted a lot of research on point-to-point experiments based on SNS-TF-QKD, and have made substantial progress. However, the expansion of SNS-TF-QKD network is still a major challenge.

[0004] With the development of society, the demand for communication capacity is increasing, and the existing technology uses the wavelength, phase, polarization, time, etc. of photons to multiplex to increase the fiber capacity. Network applications usually use fan-in modules. Fan-in multiplexing refers to calling or controlling a given multiplexing module. The degree of multiplexing of the module, the larger the fan-in, the more high-level modules that call the module, and the higher the multiplexing. However, these technologies increase the fiber capacity while gradually increasing the non-linear effects in the fiber, gradually approaching the Shannon limit, and laying a separate fiber for quantum key distribution will result in very high costs. SUMMARY

[0005] The utility model discloses to solve the problem that the existing technology increases the fiber capacity while gradually increasing the non-linear effects in the fiber, and proposes a ring-shaped multi-user quantum key distribution system based on space division multiplexing.

[0006] In order to realize the above-mentioned purpose, the technical scheme adopted by the utility model is as follows:

[0007] A kind of annular multi-user quantum key distribution system based on space division multiplexing, including Charlie relay terminal, multiple user terminals and annular quantum channel;The Charlie relay terminal and multiple user terminals are respectively connected to annular quantum channel;

[0008] The Charlie relay terminal includes multi-wavelength pulse generation module, fan-in module, first beam splitter, first fan-out module and detection module;

[0009] The output end of the multi-wavelength pulse generation module is connected with the input end of the fan-in module, the output end of the fan-in module is connected with the input end of the first beam splitter through a multi-core optical fiber, and the two output ends of the first beam splitter are respectively connected to the annular quantum channel to form a clockwise transmission link and an anticlockwise transmission link, and the output end of the clockwise transmission link and the output end of the anticlockwise transmission link are respectively connected with the input end of the detection module through the first fan-out module.

[0010] In the above-mentioned scheme, the multi-wavelength pulse generation module emits pulses of multiple wavelengths, which are first coupled into the specified core of the multi-core optical fiber through the fan-in module, and then reach the specified user terminal through the annular quantum channel, so as to realize simultaneous communication of multiple user terminals by using space division multiplexing, expand the communication capacity, and avoid the increase of nonlinear effects in the optical fiber. At the same time, by adopting the structure of sagnac ring, good phase stability is achieved.

[0011] Preferably, the Charlie relay terminal further comprises an optical attenuator;

[0012] The output end of the fan-in module is connected with the input end of the first beam splitter through the optical attenuator.

[0013] Preferably, the Charlie relay terminal further comprises a first circulator and a second circulator;

[0014] The output end of the first beam splitter is connected with the first port of the first circulator and the first port of the second circulator respectively, and the second port of the first circulator and the second port of the second circulator are respectively connected to the annular quantum channel to form a clockwise transmission link and an anticlockwise transmission link, and the third port of the first circulator and the third port of the second circulator are respectively connected with the input end of the detection module through the first fan-out module.

[0015] Preferably, the user terminal comprises a second fan-out module, an intensity modulator, a phase modulator and a Faraday mirror;

[0016] One end of the second fan-out module is connected to a ring quantum channel, the other end of the second fan-out module is connected to one end of an intensity modulator, the other end of the intensity modulator is connected to one end of a phase modulator, and the other end of the phase modulator is connected to a Faraday mirror.

[0017] Preferably, the user terminals include Alice user terminals and Bob user terminals.

[0018] Preferably, the number of Alice user terminals is equal to the number of Bob user terminals.

[0019] Preferably, the detection module includes a second beam splitter, a first single-photon detector and a second single-photon detector.

[0020] The input end of the second beam splitter is connected to the output end of the first fan-out module, and the output ends of the second beam splitter are respectively connected to the input ends of the first single-photon detector and the second single-photon detector.

[0021] Preferably, the detection module has a plurality of detection modules.

[0022] Preferably, the number of detection modules is equal to the number of Alice user terminals.

[0023] Preferably, the first beam splitter is a 50:50 beam splitter.

[0024] The beneficial technical effects of the present application are as follows:

[0025] The utility model provides a kind of ring multi-user quantum key distribution system based on space division multiplexing, multiple wavelengths of pulse are sent by multiple wavelength pulse generation module, first pass fan-in module is coupled to the specified core of multicore optical fiber, then reaches specified user terminal through ring quantum channel, utilize space division multiplexing to realize multiple user terminals simultaneously communication, expand communication capacity, also avoid the nonlinear effect of fiber increases. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is overall structural block diagram of the utility model;

[0027] Figure 2 It is module connection schematic drawing of Charlie relay end in the utility model;

[0028] Figure 3 It is module connection schematic drawing of user terminal in the utility model;

[0029] The components are as follows: 100, Charlie repeater; 110, multi-wavelength pulse generation module; 120, fan-in module; 130, first beam splitter; 140, first fan-out module; 150, detector module; 151, second beam splitter; 152, first single-photon detector; 153, second single-photon detector; 160, optical attenuator; 171, first circulator; 172, second circulator; 200, user terminal; 210, second fan-out module; 220, intensity modulator; 230, phase modulator; 240, Faraday mirror; 300, ring quantum channel. Detailed Implementation

[0030] 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.

[0031] Example 1

[0032] like Figure 1 As shown, a ring multi-user quantum key distribution system based on space division multiplexing includes a Charlie relay terminal 100, multiple user terminals 200, and a ring quantum channel 300; the Charlie relay terminal 100 and the multiple user terminals 200 are respectively connected to the ring quantum channel 300.

[0033] The Charlie relay terminal 100 includes a multi-wavelength pulse generation module 110, a fan-in module 120, a first beam splitter 130, a first fan-out module 140, and a detection module 150.

[0034] The output of the multi-wavelength pulse generation module 110 is connected to the input of the fan-in module 120. The output of the fan-in module 120 is connected to the input of the first beam splitter 130 through a multi-core optical fiber. The two outputs of the first beam splitter 130 are respectively connected to the ring quantum channel 300 to form a clockwise transmission link and a counterclockwise transmission link. The outputs of the clockwise transmission link and the counterclockwise transmission link are respectively connected to the input of the detection module 150 through the first fan-out module 140.

[0035] In the specific implementation process, the multi-wavelength pulse generation module 110 generates pulses of multiple wavelengths. These pulses are first coupled to a designated core of the multi-core optical fiber through the fan-in module 120, and then reach the designated user terminal 200 through the ring quantum channel 300. Spatial division multiplexing is used to enable simultaneous communication between multiple user terminals 200, thereby expanding the communication capacity and avoiding the increase of nonlinear effects in the optical fiber. At the same time, by adopting the Sagnac ring structure, it has excellent phase stability.

[0036] Example 2

[0037] A ring multi-user quantum key distribution system based on space division multiplexing, comprising a Charlie relay end 100, a plurality of user ends 200 and a ring quantum channel 300; the Charlie relay end 100 and the plurality of user ends 200 are connected to the ring quantum channel 300 respectively;

[0038] The Charlie relay end 100 comprises a multi-wavelength pulse generation module 110, a fan-in module 120, a first beam splitter 130, a first fan-out module 140 and a detection module 150.

[0039] The fan-in of a module refers to the number of modules that call or control a given module. It reflects the multiplexing degree of the module. The greater the fan-in, the more high-level modules that call the module, and the higher the multiplexing degree.

[0040] More specifically, the Charlie relay end 100 further comprises an optical attenuator 160.

[0041] More specifically, the Charlie relay end 100 further comprises a first circulator 171 and a second circulator 172.

[0042] The output end of the multi-wavelength pulse generation module 110 is connected to the input end of the fan-in module 120. The output end of the fan-in module 120 is connected to the input end of the first beam splitter 130 through the optical attenuator 160. The output end of the first beam splitter 130 is connected to the first port of the first circulator 171 and the first port of the second circulator 172 respectively. The second port of the first circulator 171 and the second port of the second circulator 172 are connected to the ring quantum channel 300 to form a clockwise transmission link and an anticlockwise transmission link. The third port of the first circulator 171 and the third port of the second circulator 172 are connected to the input end of the detection module 150 through the first fan-out module 140.

[0043] More specifically, the user end 200 comprises Alice user ends (Alice1, Alice2, …, Alicen) and Bob user ends (Bob1, Bob2, …, Bobn).

[0044] More specifically, the number of Alice user ends is equal to the number of Bob user ends.

[0045] More specifically, the detection module 150 comprises a second beam splitter 151, a first single-photon detector 152 and a second single-photon detector 153.

[0046] The input end of the second beam splitter 151 is connected with the output end of the first fan-out module 140, and the output end of the second beam splitter 151 is connected with the input end of the first single-photon detector 152 and the input end of the second single-photon detector 153 respectively.

[0047] More specifically, the detection module 150 has a plurality of.

[0048] More specifically, the number of the detection module 150 is equal to the number of the Alice user end.

[0049] More specifically, the first beam splitter 130 is a 50:50 beam splitter.

[0050] More specifically, the user end 200 includes a second fan-out module 210, an intensity modulator 220, a phase modulator 230 and a Faraday mirror 240.

[0051] One end of the second fan-out module 210 accesses the ring quantum channel 300, and the other end of the second fan-out module 210 is connected with one end of the intensity modulator 220, the other end of the intensity modulator 220 is connected with one end of the phase modulator 230, and the other end of the phase modulator 230 is connected with the Faraday mirror 240.

[0052] In the specific implementation process, the multi-wavelength pulse generation module 110 emits pulses of multiple wavelengths (including quantum signal pulses and synchronous light pulses), which are coupled into the designated core of the multi-core optical fiber through the fan-in module 120, attenuated to a specified power of optical signals through the attenuator, and then divided into two optical signals with the same power through the first beam splitter 130, wherein one of the optical signals enters the ring quantum channel 300 and transmits along the clockwise direction of the optical fiber link, and the other optical signal enters the ring quantum channel 300 and transmits along the counterclockwise direction of the optical fiber link;

[0053] The optical signals transmitted along the clockwise (counterclockwise) direction are not modulated when passing through the Bob user end (Alice user end), and the optical signals of specific wavelengths are separated out through the second fan-out module 210 when passing through the Alice user end (Bob user end), and the separated optical signals are modulated in intensity and phase at the Alice user end (Bob user end).

[0054] The intensity and phase modulation adopts the protocol of SNS-TF-QKD, and the Alice user end and the Bob user end independently select to send signal state pulses (Z basis) or decoy state pulses (X basis). If the signal state pulses are selected to be sent, coherent state pulses with an average photon number of μ are sent with a probability of ∈ wherein, φ A (φ B ) is a random phase, γ a (γb ) is global phase. With probability 1-∈, no pulse is sent; if a decoy state pulse is chosen to be sent, a coherent state pulse with intensity v is sent, where v can be chosen among several different values.

[0055] The optical signal is then reflected back into the fiber link by the Faraday mirror 240 for further transmission. The optical signal transmitted along the clockwise direction and the optical signal transmitted along the counterclockwise direction finally return to the Charlie relay end 100, are demultiplexed by the first fan-out module 140, and enter the corresponding probe modules 150 to detect the interference results.

[0056] Alice user end and Bob user end perform the basis selection and screening of the detection results. The following two cases are valid events: (1) when Alice user end and Bob user end both select Z basis, the detector has and only has one response; (2) when Alice user end and Bob user end both select X basis, the detector has and only has one response, and the selected intensity is the same, and the modulated random phase satisfies 1- |cos(δ A -δ B )≤|λ|, where λ and the number of phase slices are related.

[0057] Finally, through error correction and security enhancement, the final quantum key is obtained.

[0058] 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 spatially multiplexed ring multiuser quantum key distribution system based on, The Charlie relay terminal, a plurality of user terminals and a ring-shaped quantum channel are included. The Charlie relay terminal includes a multi-wavelength pulse generation module, a fan-in module, a first beam splitter, a first fan-out module and a detection module. The output end of the multi-wavelength pulse generation module is connected with the input end of the fan-in module, the output end of the fan-in module is connected with the input end of the first beam splitter through a multi-core optical fiber, and the two output ends of the first beam splitter are connected with the ring-shaped quantum channel to form a clockwise transmission link and an anticlockwise transmission link.

2. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The Charlie relay terminal further includes an optical attenuator. The output end of the fan-in module is connected with the input end of the first beam splitter through the optical attenuator.

3. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The Charlie relay terminal further includes a first circulator and a second circulator. The output end of the first beam splitter is connected with the first port of the first circulator and the first port of the second circulator, respectively, the second port of the first circulator and the second port of the second circulator are connected with the ring-shaped quantum channel to form the clockwise transmission link and the anticlockwise transmission link, and the third port of the first circulator and the third port of the second circulator are connected with the input end of the detection module through the first fan-out module.

4. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The user terminal includes a second fan-out module, an intensity modulator, a phase modulator and a Faraday mirror. One end of the second fan-out module is connected with the ring-shaped quantum channel, the other end of the second fan-out module is connected with one end of the intensity modulator, the other end of the intensity modulator is connected with one end of the phase modulator, and the other end of the phase modulator is connected with the Faraday mirror.

5. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The user terminal includes an Alice user terminal and a Bob user terminal.

6. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 5, wherein, The number of Alice user terminals is equal to the number of Bob user terminals.

7. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The detection module includes a second beam splitter, a first single-photon detector and a second single-photon detector. The input end of the second beam splitter is connected with the output end of the first fan-out module, and the output end of the second beam splitter is connected with the input end of the first single-photon detector and the input end of the second single-photon detector, respectively.

8. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The detection module has a plurality of detection modules.

9. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 6, wherein, The number of detection modules is equal to the number of Alice user terminals.

10. The ring-shaped multi-user quantum key distribution system based on space-division multiplexing according to claim 1, wherein, The first beam splitter is a 50:50 beam splitter.

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