Plug-and-play quantum secret key distribution system and method based on time-phase encoding, transmitting end and receiving end

A technology of quantum key distribution and phase encoding, applied in the field of plug-and-play quantum key distribution system, can solve the problems of difficult Mach-Zehnder interferometer arm length difference phase stabilization, affecting the repetition frequency of the system, and reducing precise modulation, etc. Achieve the effects of stable arm length difference and phase, avoiding low coding rate and reducing insertion loss

Active Publication Date: 2016-11-23
ZHEJIANG SHENZHOU QUANTUM NETWORK TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the existing technology and the influence of the external environment, it is difficult to ensure the phase stability of the arm length difference between the two unequal arms Mach-Zehnder interferometers for a long time
[0012] 2. The existing phase encoding system needs to add a phase modulator in the measurement part of the receiving end, which brings additional attenuation and reduces the coding rate
[0013] 3. The existing phase encoding system needs to generate high-speed random electrical signals to actively control the selection of the unbalanced base vector, thereby affecting the repetition frequency of the system and the precise modulation of the phase and reducing the coding rate

Method used

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  • Plug-and-play quantum secret key distribution system and method based on time-phase encoding, transmitting end and receiving end
  • Plug-and-play quantum secret key distribution system and method based on time-phase encoding, transmitting end and receiving end
  • Plug-and-play quantum secret key distribution system and method based on time-phase encoding, transmitting end and receiving end

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Embodiment 2

[0086] In this embodiment, the difference from Embodiment 1 is that the polarization beam splitter 5 is replaced by a beam splitter 5a, and the 90-degree polarization rotator is omitted at the same time, and the original delay line 4a of the long arm part is retained. For the modified part, see image 3 .

Embodiment 3

[0088] In this embodiment, the difference from Embodiment 1 lies in the unequal arm interference module and related single photon detectors. In this embodiment, the unequal arm MZ interferometer is changed to an unequal arm interferometer based on Michelson's principle Realized, and correspondingly made adaptive improvements to the single photon detector.

[0089] see Figure 4 , the pulse light source 1 emits linearly polarized light pulses, passes through the circulator 2 and reaches the polarization beam splitter 15, which transmits horizontally polarized light pulses (|H>) and reflects vertically polarized light pulses (|V>).

[0090] The horizontally polarized light pulse (|H>) travels the long arm, and after being delayed by the delay line 4a, it is reflected by the 90-degree rotating Faraday reflector 16 (the second 90-degree rotating Faraday reflector), and the horizontally polarized light pulse (|H>) The vertically polarized light pulse (|V>) is reflected and output ...

Embodiment 4

[0094] see Figure 5 , in this embodiment, the difference from Embodiment 1 is that the X-based vector detection module is improved, and the two single-photon detectors in the X-based vector detection module are replaced by the same single-photon detector, which will reduce the cost .

[0095] At Bob's end, when two reflected light pulses with the same polarization interfere on the beam splitter, since the phase modulator at Alice's end has completed the X base vector phase encoding, the effective phase difference of the two reflected light pulses is 0 or pi .

[0096] If the phase difference is 0, the short arm passes through the circulator 2 to reach the polarization maintaining polarization beam splitter 14 (or adopts a beam splitter) and is transmitted to the single photon detector 22 .

[0097] If the phase difference is pi, the long arm passes through the delay line 4b and then reaches the polarization-maintaining polarization beam splitter 14 (or adopts a beam splitte...

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Abstract

The invention discloses a plug-and-play quantum secret key distribution system and method based on time-phase encoding, a transmitting end and a receiving end. The plug-and-play quantum secret key distribution system comprises the transmitting end and the receiving end which are in mutually optical connection, a coding module in the transmitting end comprises a Z basis vector time coding module coding optical signals according to any sequence and a phase coding module which is an X basis vector phase coding module, and a decoding module in the receiving end is matched with the coding module. The plug-and-play quantum secret key distribution method includes: after an Alice end receives and reflects optical signals from a Bob end, performing Z basis vector time coding and phase coding; sending the optical signals after going through Z basis vector time coding and phase coding to the Bob end for decoding and detecting, wherein phase coding refers to X basis vector phase coding. Improved time-phase coding is used, so that ultrahigh-contrast coding and decoding can be realized, and code generating rate can be increased.

Description

technical field [0001] The invention relates to the field of quantum key distribution, in particular to a plug-and-play quantum key distribution system based on time-phase encoding. Background technique [0002] As a new research field combining quantum mechanics, electronic information science and computer technology, quantum secure communication has attracted the attention of people from all walks of life. In order to ensure the secure transmission of data, secure key exchange must be guaranteed between users. Today, quantum key distribution has become an effective way to distribute absolutely secure keys through public channels. Different from the traditional confidentiality principle of classical cryptographic communication, quantum key distribution uses the basic principles of quantum mechanics as support, such as Heisenberg’s uncertainty principle, quantum non-cloning theorem, etc., to realize unconditionally secure random key sharing. [0003] Many QKD devices can w...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L9/08
CPCH04L9/0819H04L9/0852H04L9/0858
Inventor 富尧
Owner ZHEJIANG SHENZHOU QUANTUM NETWORK TECH CO LTD
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