CN210112021U - Polarization encoding quantum key distribution system - Google Patents
Polarization encoding quantum key distribution system Download PDFInfo
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- CN210112021U CN210112021U CN201921177123.7U CN201921177123U CN210112021U CN 210112021 U CN210112021 U CN 210112021U CN 201921177123 U CN201921177123 U CN 201921177123U CN 210112021 U CN210112021 U CN 210112021U
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Abstract
The utility model relates to a polarization encoding quantum key distribution system, which comprises a sending module and a receiving module; the transmitting module comprises a pulse laser, an intensity modulator, a polarization encoder and an electrically adjustable attenuator; the output end of the pulse laser is connected with the input end of the intensity modulator, the output end of the intensity modulator is connected with the input end of the polarization encoder, the output end of the polarization encoder is connected with the input end of the electrically adjustable attenuator, and the output end of the electrically adjustable attenuator is connected with the input end of the receiving module; the receiving module comprises a polarization controller, a polarization decoder, a third polarization beam splitter, a first single-photon detector and a second single-photon detector. The utility model discloses a distribution system has the advantage that system architecture is simple, the cost is lower, and has avoided the attack to non-ideal beam splitter when selecting the basis passively.
Description
Technical Field
The utility model belongs to optic fibre quantum key distribution system field, specifically say and relate to a polarization coding quantum key distribution system.
Background
With the development of science and technology, and in particular the threat of quantum computers, classical cryptography based on computational complexity will face unprecedented challenges. The quantum key distribution technology ensures unconditional safety by the basic principle of quantum mechanics, and can meet the increasing requirements of people on safe communication by combining a symmetric encryption system of one-time pad. At present, the quantum key distribution system of the BB84 protocol is mature and is already put into practical use.
A polarization encoded QKD system is a typical system of a BB84 protocol quantum key distribution system. The system mainly comprises a single photon source, a polarization controller, a polarization beam splitter, a 3dB coupler and a single photon detector. At a transmitting end, each polarization state is generated by a laser and is coupled into the same path of optical fiber through a polarization beam splitter, a 3dB coupler and the like; the receiving end is divided into two paths through the beam splitter, divided into two groups of basis vectors, and subjected to polarization analysis through the polarization beam splitter, and then detected on the single photon detector. The transmitting end of the polarization encoding QKD system needs 4 or 8 (generating a decoy state) single-photon sources, and the receiving end needs 4 single-photon detectors. Therefore, the system has the disadvantages of large volume, high cost, complex system and the like.
SUMMERY OF THE UTILITY MODEL
According to the problem that exists among the prior art, the utility model provides a polarization coding quantum key distribution system, it has the advantage that system's simple structure, cost are lower, and has avoided the attack to non-ideal beam splitter during passive election basis.
The utility model adopts the following technical scheme:
a polarization encoding quantum key distribution system comprises a sending module and a receiving module; the transmitting module comprises a pulse laser, an intensity modulator, a polarization encoder and an electrically adjustable attenuator; the output end of the pulse laser is connected with the input end of the intensity modulator, the output end of the intensity modulator is connected with the input end of the polarization encoder, the output end of the polarization encoder is connected with the input end of the electrically adjustable attenuator, and the output end of the electrically adjustable attenuator is connected with the input end of the receiving module;
the receiving module comprises a polarization controller, a polarization decoder, a third polarization beam splitter, a first single-photon detector and a second single-photon detector; the input end of the polarization controller is connected with the output end of the electrically adjustable attenuator, the output end of the polarization controller is connected with the input end of the polarization decoder, the output end of the polarization decoder is connected with the input end of the third polarization beam splitter, and the output end of the third polarization beam splitter is respectively connected with the input ends of the first single-photon detector and the second single-photon detector.
Preferably, the polarization encoder comprises a first polarization beam splitter and a first phase modulator; the output end of the intensity modulator is connected with the first input end of the first polarization beam splitter, the first output end of the first polarization beam splitter is connected with the input end of the first phase modulator, the output end of the first phase modulator is connected with the second input end of the first polarization beam splitter, and the second output end of the first polarization beam splitter is connected with the input end of the electrically adjustable attenuator.
Further preferably, the polarization decoder comprises a second polarization beam splitter and a second phase modulator; the output end of the polarization controller is connected with the first input end of the second polarization beam splitter, the first output end of the second polarization beam splitter is connected with the input end of the second phase modulator, the output end of the second phase modulator is connected with the second input end of the second polarization beam splitter, and the second output end of the second polarization beam splitter is connected with the input end of the third polarization beam splitter.
More preferably, the connecting fibers between the intensity modulator and the first polarization beam splitter and between the third polarization beam splitter and the second polarization beam splitter are all set to be welded at 45 degrees; one connecting optical fiber between the first polarization beam splitter and the first phase modulator is welded at 90 degrees, and a delay line is arranged in the other connecting optical fiber; one connecting optical fiber between the second polarization beam splitter and the second phase modulator is welded at 90 degrees, and a delay line is arranged in the other connecting optical fiber.
The beneficial effects of the utility model reside in that:
1) compared with the traditional polarization coding QKD system, the utility model discloses only need a pulse laser (a single photon source) and a phase modulator (be first phase modulator) can produce the required four kinds of polarization states of BB84 agreement, receiving module only needs two single photon detectors, replaces four detectors of traditional polarization coding QKD system to realize signal reception, has simplified system architecture greatly, has reduced manufacturing cost.
2) The utility model discloses the use constitutes Sagnac loop structure through polarization beam splitter, carries out 90 butt fusion through the optic fibre between intra-annular polarization beam splitter and the phase modulator, has avoided light pulse to return from polarization beam splitter's incident end, and from another port outgoing, has additionally saved the optical circulator, is favorable to simplifying system architecture, reduction in production cost.
3) The utility model discloses a send the module and only need a pulse laser, avoided in the traditional polarization coding QKD system because the inconsistent side channel leak that leads to of a plurality of laser instrument wavelength; and the receiving module adopts the phase modulator to randomly modulate to actively select the base, thereby avoiding the attack to the non-ideal beam splitter during the passive base selection.
Drawings
Fig. 1 is a diagram showing a structure of a distribution system according to the present invention.
Reference numerals: 1-sending module, 2-receiving module, 11-pulse laser, 12-intensity modulator, 13-polarization encoder, 14-electrically adjustable attenuator, 15-first polarization beam splitter, 16-first phase modulator, 21-polarization controller, 22-polarization decoder, 23-third polarization beam splitter, 24-first single-photon detector, 25-second single-photon detector, 26-second polarization beam splitter, and 27-second phase modulator.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1, a polarization-encoded quantum key distribution system includes a transmitting module 1 and a receiving module 2; the transmitting module 1 comprises a pulse laser 11, an intensity modulator 12, a polarization encoder 13 and an electrically adjustable attenuator 14; the output end of the pulse laser 11 is connected with the input end of the intensity modulator 12, the output end of the intensity modulator 12 is connected with the input end of the polarization encoder 13, the output end of the polarization encoder 13 is connected with the input end of the electrically adjustable attenuator 14, and the output end of the electrically adjustable attenuator 14 is connected with the input end of the receiving module 2;
the receiving module 2 comprises a polarization controller 21, a polarization decoder 22, a third polarization beam splitter 23, a first single-photon detector 24 and a second single-photon detector 25; the input end of the polarization controller 21 is connected with the output end of the electrically adjustable attenuator 14, the output end of the polarization controller 21 is connected with the input end of the polarization decoder 22, the output end of the polarization decoder 22 is connected with the input end of the third polarization beam splitter 23, and the output end of the third polarization beam splitter 23 is respectively connected with the input ends of the first single-photon detector 24 and the second single-photon detector 25.
The polarization encoder 13 includes a first polarization beam splitter 15 and a first phase modulator 16; the output end of the intensity modulator 12 is connected to the first input end of the first polarization beam splitter 15, the first output end of the first polarization beam splitter 15 is connected to the input end of the first phase modulator 16, the output end of the first phase modulator 16 is connected to the second input end of the first polarization beam splitter 15, and the second output end of the first polarization beam splitter 15 is connected to the input end of the electrically adjustable attenuator 14.
The polarization decoder 22 comprises a second polarization beam splitter 26 and a second phase modulator 27; the output end of the polarization controller 21 is connected to the first input end of the second polarization beam splitter 26, the first output end of the second polarization beam splitter 26 is connected to the input end of the second phase modulator 27, the output end of the second phase modulator 27 is connected to the second input end of the second polarization beam splitter 26, and the second output end of the second polarization beam splitter 26 is connected to the input end of the third polarization beam splitter 23.
Specifically, the connecting fiber between the intensity modulator 12 and the first polarization beam splitter 15 is set to be welded at 45 ° to generate polarized lightEnters the first polarization beam splitter 15;
one of the connecting fibers between the first polarization beam splitter 15 and the first phase modulator 16 is set to be welded at 90 degrees, and the other connecting fiber is provided with a delay line; one connecting optical fiber between the second polarization beam splitter 26 and the second phase modulator 27 is set to be welded at 90 degrees, and the other connecting optical fiber is provided with a delay line; the connecting optical fiber between the third polarization beam splitter 23 and the second polarization beam splitter 26 is set to be welded at 45 degrees;
specifically, the connection fibers between the first polarization beam splitter 15 and the first phase modulator 16 and between the second polarization beam splitter 26 and the second phase modulator 27 are all polarization maintaining fibers.
The utility model discloses a distribution system is at the during operation, by pulse process that pulse laser 11 sent intensity modulator 12's modulation back, transmission to first polarization beam splitter 15, pulse component | H of outgoing after the beam splitting via first polarization beam splitter 15>、|V>The pulse component | H transmitted to the first phase modulator 16 is phase-modulated by controlling the voltage of the first phase modulator 16>、|V>Generate a phase difference therebetween
The polarization state thus produced is
Four phase differences
The corresponding four polarization states are shown in table 1:
table 1: four phase differences
Corresponding four polarization states
The modulated pulses are attenuated into single photon magnitude optical pulses by an electrically adjustable attenuator 14; the optical pulses are subjected to polarization state recovery through the polarization controller 21, that is, the received optical pulses are compensated to the polarization state consistent with the polarization state of the electrically adjustable attenuator 14 of the sending module, and then transmitted to the second polarization beam splitter 26, and the optical pulses split by the second polarization beam splitter 26 and emitted are transmitted to the second phase modulator 27 for random 2-phase modulation, which is 0 and pi/2 respectively; by adjusting the voltage of the second phase modulator 27, the phase difference between the two components of the optical pulse is
The modulated light pulses are respectively transmitted to a first single-photon detector 24 and a second single-photon detector 25 after being split by a third polarization beam splitter 23; finally, the two split light pulses are measured by the first single-photon detector 24 and the second single-photon detector 25, respectively, for photon counting.
The four phases are modulated by the transmitting module 1, and the two phases are modulated by the receiving module 2, so that the response probability tables of the corresponding first single-photon detector 24(SPD1) and second single-photon detector 25(SPD2) are shown in table 2:
table 2: first single-photon detector 24(SPD1) and second single-photon detector 25(SPD2) response probability tables
Photon counts are measured by the first and second single- photon detectors 24, 25 for subsequent processing to generate the security key.
The distribution system of the utility model can generate four polarization states required by BB84 protocol only by a pulse laser and a phase modulator, and the receiving module only needs two single-photon detectors to replace four detectors of the traditional polarization encoding QKD system to realize signal receiving; and simultaneously, the utility model discloses the use constitutes Sagnac loop structure through polarization beam splitter, through the 90 butt fusion of optic fibre between intra-annular polarization beam splitter and the phase modulator, has avoided light pulse to return from polarization beam splitter's incident end, and from another port outgoing, has additionally saved the optical circulator. Therefore, the utility model discloses a distribution system has simplified system architecture, has reduced manufacturing cost greatly.
The utility model discloses a send the module and only need a pulse laser, avoided in the traditional polarization coding QKD system because the inconsistent side channel leak that leads to of a plurality of laser instrument wavelength; and the receiving module adopts the phase modulator to randomly modulate to actively select the base, thereby avoiding the attack to the non-ideal beam splitter during the passive base selection.
To sum up, the utility model provides a polarization encoding quantum key distribution system, it has the advantage that system's simple structure, cost are lower, and has avoided the attack to non-ideal beam splitter during passive election base.
Claims (4)
1. A polarization encoded quantum key distribution system, characterized by: comprises a sending module (1) and a receiving module (2); the transmitting module (1) comprises a pulse laser (11), an intensity modulator (12), a polarization encoder (13) and an electrically adjustable attenuator (14); the output end of the pulse laser (11) is connected with the input end of the intensity modulator (12), the output end of the intensity modulator (12) is connected with the input end of the polarization encoder (13), the output end of the polarization encoder (13) is connected with the input end of the electrically adjustable attenuator (14), and the output end of the electrically adjustable attenuator (14) is connected with the input end of the receiving module (2);
the receiving module (2) comprises a polarization controller (21), a polarization decoder (22), a third polarization beam splitter (23), a first single-photon detector (24) and a second single-photon detector (25); the input end of the polarization controller (21) is connected with the output end of the electrically adjustable attenuator (14), the output end of the polarization controller (21) is connected with the input end of the polarization decoder (22), the output end of the polarization decoder (22) is connected with the input end of the third polarization beam splitter (23), and the output end of the third polarization beam splitter (23) is respectively connected with the input ends of the first single-photon detector (24) and the second single-photon detector (25).
2. A polarization encoded quantum key distribution system according to claim 1, wherein: the polarization encoder (13) comprises a first polarization beam splitter (15) and a first phase modulator (16); the output end of the intensity modulator (12) is connected with the first input end of the first polarization beam splitter (15), the first output end of the first polarization beam splitter (15) is connected with the input end of the first phase modulator (16), the output end of the first phase modulator (16) is connected with the second input end of the first polarization beam splitter (15), and the second output end of the first polarization beam splitter (15) is connected with the input end of the electrically adjustable attenuator (14).
3. A polarization encoded quantum key distribution system according to claim 2, wherein: the polarization decoder (22) comprises a second polarization beam splitter (26) and a second phase modulator (27); the output end of the polarization controller (21) is connected with the first input end of the second polarization beam splitter (26), the first output end of the second polarization beam splitter (26) is connected with the input end of the second phase modulator (27), the output end of the second phase modulator (27) is connected with the second input end of the second polarization beam splitter (26), and the second output end of the second polarization beam splitter (26) is connected with the input end of the third polarization beam splitter (23).
4. A polarization encoded quantum key distribution system according to claim 3, wherein: connecting optical fibers between the intensity modulator (12) and the first polarization beam splitter (15) and between the third polarization beam splitter (23) and the second polarization beam splitter (26) are all set to be welded at 45 degrees; one connecting optical fiber between the first polarization beam splitter (15) and the first phase modulator (16) is set to be welded at 90 degrees, and a delay line is arranged in the other connecting optical fiber; one connecting optical fiber between the second polarization beam splitter (26) and the second phase modulator (27) is set to be welded at 90 degrees, and a delay line is arranged in the other connecting optical fiber.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110380853A (en) * | 2019-07-24 | 2019-10-25 | 赵义博 | A kind of polarization encoder quantum key distribution system |
| CN111464302A (en) * | 2020-05-10 | 2020-07-28 | 神盾迅波(北京)量子科技发展有限公司 | Quantum key distribution system based on B92 protocol |
| WO2021188045A1 (en) * | 2020-03-17 | 2021-09-23 | Nanyang Technological University | System and apparatuses for measurement-device-independent quantum key distribution |
| CN115296748A (en) * | 2022-07-14 | 2022-11-04 | 武汉光谷信息光电子创新中心有限公司 | Polarization modulator and quantum key distribution system |
-
2019
- 2019-07-24 CN CN201921177123.7U patent/CN210112021U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110380853A (en) * | 2019-07-24 | 2019-10-25 | 赵义博 | A kind of polarization encoder quantum key distribution system |
| WO2021188045A1 (en) * | 2020-03-17 | 2021-09-23 | Nanyang Technological University | System and apparatuses for measurement-device-independent quantum key distribution |
| CN111464302A (en) * | 2020-05-10 | 2020-07-28 | 神盾迅波(北京)量子科技发展有限公司 | Quantum key distribution system based on B92 protocol |
| CN115296748A (en) * | 2022-07-14 | 2022-11-04 | 武汉光谷信息光电子创新中心有限公司 | Polarization modulator and quantum key distribution system |
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Assignee: ZHEJIANG QUANTUM TECHNOLOGIES Co.,Ltd. Assignor: Zhao Yibo|Song Xiaotian Contract record no.: X2022330000342 Denomination of utility model: A Polarization Coded Quantum Key Distribution System Granted publication date: 20200221 License type: Common License Record date: 20220727 |
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