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A Quantum Cryptography Implementation Method Based on Quantum Light Source

A technology of quantum cryptography and implementation method, applied in the application field, can solve the problems of low coincidence rate, unreachable signal state of optimal strength, poor performance, etc., and achieve the effect of eliminating intensity modulation error, excellent practical performance, and avoiding information leakage

Active Publication Date: 2022-01-28
NANJING UNIV OF POSTS & TELECOMM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the actual quantum cryptography scheme, due to some defects in the previous protocols and systems based on quantum light sources, the actual performance is poor, so most of the QKD systems use WCS
[0004] In the conventional scheme of generating HSPS, SAPD (Silicon Avalanche Photo-Diode, silicon avalanche diode) is commonly used as a single photon detector for local detection, and the saturation threshold of the detector will limit the intensity of pump power and signal light, so the optimal strength of the signal state cannot be reached
In addition, using the current technology, due to the unsatisfactory coupling efficiency and detection efficiency, the photon pairs generated by the PDC process have a low coincidence rate, resulting in a low marking efficiency of HSPS, which obviously reduces the key extraction using the HSPS protocol. Rate
Moreover, in the QKD system using phase encoding, the signal light needs to pass through the Mach-Zehnder (MZ) or Faraday-Michslson interferometer, which usually has a large system loss, especially when using a quantum light source.
Therefore, there are few QKD experiments based on quantum light sources so far, and most of them have poor performance compared with WCS

Method used

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  • A Quantum Cryptography Implementation Method Based on Quantum Light Source
  • A Quantum Cryptography Implementation Method Based on Quantum Light Source
  • A Quantum Cryptography Implementation Method Based on Quantum Light Source

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] In the scheme of the present invention, a decoy state method and a novel low-loss unequal-arm MZ interferometer are adopted.

[0021] In the QKD system conventionally using HSPS light sources of the present invention, the dual-mode light field state obtained from the parametric down-conversion process can be described as:

[0022]

[0023] Wherein|n>represents an n photon state, and Pn is the corresponding photon number distribution, and in the present invention, Pn obeys Poisson distribution; I and S represent leisure light and signal light respectively, and leisure light (mode I) is usually emitted by Alice Local detection is performed, while the signal light (mode S) is sent to the receiving end Bob.

[0024] The scheme for generating passive HSPS of the present invention is explained below. The main process can be divided into the following steps: the first step, after the parametric down-conversion process, the leisure light is divided into two parts after pass...

Embodiment 2

[0041] For the sake of simplicity in the experiment, only three events such as x, y, z are used to estimate the key extraction rate. The parameters used in the experiment satisfy 010 20 0 1 =tη 10 , η 2 =(1-t)η 20 , with η 1 >0,1-η 2 >0,1-η 1 -η 2 >0. due to d 1 >>1, for any n≥2, we can get:

[0042]

[0043] So for any n≥2 the following inequalities hold:

[0044]

[0045] Using the above formula and considering statistical fluctuations, the lower bound Y of the single photon responsivity can be obtained 1 L and an upper bound on the single-photon bit error rate

[0046]

[0047] where e 0 (=0.5) and Y 0 Respectively represent the qubit bit error rate and dark count at Bob's end in the vacuum state. Q ξ and E ξ (ξ=x, y, z) represent the total responsivity and qubit error in any ξ state, respectively;

[0048]

[0049] γ is the standard deviation of statistical fluctuation analysis, which is assumed to be a constant γ=5.3, and the corresponding...

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Abstract

The invention discloses a quantum cipher realization method based on a quantum light source. The method generates a marked single photon source through a PDC process, sends signal light to a receiving end, and uses leisure light for local detection. The local detection at the sending end consists of a beam splitter (BS) and two detectors (D1, D2). The casual light triggers the two detectors after passing through the beam splitter, resulting in four different response events, which are recorded and utilized. Different response events estimate and process the signal received by the receiving end, and extract the key. Due to the use of a new passive decoy state method, the response rate and bit error rate of single photons can be accurately estimated; in addition, due to the use of low-loss unequal-arm MZ interferometer, the loss of the system itself is greatly reduced; and then the single-mode standard commercial Light has achieved a quantum light source-based QKD system transmission distance of more than 200km, and the final key extraction rate is two orders of magnitude higher than that of previous QKD systems using quantum light sources.

Description

technical field [0001] The invention relates to a quantum cryptography realization method based on a quantum light source, in particular to a quantum light source, which is suitable for application technical fields such as quantum communication and quantum cryptography. Background technique [0002] Based on the theory of quantum mechanics, QKD (Quantum Key Distribution, Quantum Key Distribution) can send keys between legitimate communication parties (Alice and Bob) in an unconditional and secure manner, combined with the one-time pad algorithm in modern cryptosystems, thus It can realize unconditional and secure confidential information transmission. But in fact, due to the unsatisfactory light source, equipment, transmission channel, etc., the eavesdropper (Eve) can take advantage of these shortcomings to take corresponding attacks, so the absolute security endowed by quantum mechanics cannot be realized. To address the above shortcomings, time-shift attacks, photon numbe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L9/08H04B10/70
CPCH04B10/70H04L9/0852
Inventor 王琴张春辉丁华健张春梅
Owner NANJING UNIV OF POSTS & TELECOMM
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