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Phase encoding device for quantum key distribution and quantum key distribution system

A quantum key distribution and phase encoding technology, which is applied in the field of phase encoding devices and quantum key distribution systems, can solve the problems of high cost, complexity and high requirements, so as to improve energy utilization, improve security code rate, reduce The effect of cost and complexity

Active Publication Date: 2021-11-26
ZHEJIANG QUANTUM TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of the above defects in the prior art, the present invention proposes a phase encoding device for quantum key distribution and a quantum key distribution system to solve the high requirements of the quantum key distribution system for the phase modulator drive circuit in the prior art. , high cost and complexity and other technical defects, and the use of polarization multiplexing to improve the energy utilization rate of the interferometer, which in turn can improve the security coding rate of the system

Method used

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  • Phase encoding device for quantum key distribution and quantum key distribution system
  • Phase encoding device for quantum key distribution and quantum key distribution system
  • Phase encoding device for quantum key distribution and quantum key distribution system

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Embodiment 1

[0038] The structure of the phase encoding device is: the unequal arm polarization interferometer includes a first beam splitter BS1 and a polarization beam combiner PBC, the first optical path selection element OS1 is a first optical switch OSW1, and the second The optical path selection element OS2 is a beam combiner BC, and the phase encoding device further includes a third laser L3, a third beam splitter BS3, a second circulator CIR2, and a third circulator CIR3. The third laser L3, as a seed laser, is connected to the input port of the third beam splitter BS3, and the two output ports of the third beam splitter BS3 are connected to the second circulator CIR2 and the third circulator CIR3 respectively. connected to one port, the second ports of the second circulator CIR2 and the third circulator CIR3 are respectively connected to the first laser L1 and the second laser L2, the third ports of the second circulator CIR2 and the third circulator CIR3 They are respectively con...

Embodiment 2

[0047] The structure of the phase encoding device is: the unequal arm polarization interferometer includes a first beam splitter BS1 and a polarization beam combiner PBC, the first optical path selection element OS1 is a fourth beam splitter BS4, and the first beam splitter BS4 The second optical path selection element OS2 is a second optical switch OSW2, the polarization beam combiner PBC includes four ports, and the phase encoding device further includes a fourth laser L4, which is connected to the fourth port of the polarization beam combiner PBC.

[0048] The two-phase encoding process of the embodiment includes:

[0049] The fourth laser L4, as a seed laser, enters the first laser L1 and the second laser L2 through the polarization beam combiner PBC from the opposite direction through the short arm of the unequal-arm polarization interferometer, and performs injection locking on the two respectively. When the first laser L1 is triggered and the second laser L2 is not trig...

Embodiment 3

[0053] The structure of the phase encoding device is: the unequal arm polarization interferometer includes a second beam splitter BS2, a first polarizer POL1, a second polarizer POL2, a first mirror M1, a second mirror M2 and The first circulator CIR1. The polarization-maintaining fiber between the first port of the second beam splitter BS2 and the first laser L1 is fused at 45°, and the polarization-maintaining fiber between the first port of the first circulator CIR1 and the second laser L2 Perform 45° fusion splicing, the second port of the first circulator CIR1 is connected to the second port of the second beam splitter BS2, the third port of the first circulator CIR1 is used as the third port of the unequal arm polarization interferometer port, the first polarizer POL1 is placed at the third port of the second beam splitter BS2, the angle between the polarization direction and the horizontal direction is 0°, and the second polarizer POL2 is placed at the second beam split...

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Abstract

The invention discloses a phase encoding device for quantum key distribution. The phase encoding device comprises a first laser L1, a second laser L2, an unequal-arm polarization interferometer, a first optical path selection element OS1, a second optical path selection element OS2 and a quarter-wave plate QWP. The first optical path selection element OS1 and the second optical path selection element OS2 form an equal-armed Mach-Zehnder interferometer, the quarter-wave plate QWP is located on one arm of the equal-armed Mach-Zehnder interferometer, and the invention further provides a quantum key distribution system. Compared with the prior art, the phase encoding device has the advantages that four phase encoding states required by a BB84 protocol can be prepared without a phase modulator, polarization of two time modes is perpendicular to each other, non-interference components are easy to eliminate through polarization selection, and the energy utilization rate is increased. The cost and complexity of the coding device can be reduced, and the secure code rate of the quantum key distribution system can be improved.

Description

technical field [0001] The invention relates to the technical field of quantum phase encoding, in particular to a phase encoding device and a quantum key distribution system for quantum key distribution. Background technique [0002] Quantum key distribution (quantum key distribution, QKD) can provide unconditionally secure key distribution for long-distance communication parties, and its information theory security is guaranteed by the basic principles of quantum mechanics. At present, the quantum key distribution system of the BB84 protocol is becoming more and more mature and has become practical. The commonly used encoding methods of the BB84 protocol are polarization encoding and phase encoding. Due to the birefringence effect of the optical fiber channel, it is easy to be affected by the environment, resulting in random changes in the polarization state of photons, and the polarization encoding method is not stable enough, so phase encoding is often used. Such as fi...

Claims

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Application Information

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IPC IPC(8): H04L9/08H04B10/70H04B10/556
CPCH04L9/0858H04B10/70H04B10/5561
Inventor 齐若琳蒋荻席鹏
Owner ZHEJIANG QUANTUM TECH CO LTD
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