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Phase post-selection-based decoy state MDI-QKD method and system

A decoy state and post-selection technology, applied in key distribution, can solve the problems of constraints and the upper limit of single-photon phase inversion bit error rate, and achieve high key rate, which is beneficial to long-distance quantum key distribution. Effect

Pending Publication Date: 2022-04-05
JINAN INST OF QUANTUM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The finite code length effect under the X base vector leads to an excessively large upper limit of the single photon phase inversion bit error rate, which is an important reason for restricting the key rate of the MDI-QKD system

Method used

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  • Phase post-selection-based decoy state MDI-QKD method and system
  • Phase post-selection-based decoy state MDI-QKD method and system
  • Phase post-selection-based decoy state MDI-QKD method and system

Examples

Experimental program
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Effect test

Embodiment 1

[0058] In the traditional decoy state MDI-QKD system, the state of weakly coherent state (WCS) light source emitting pulse can be expressed as a form related to intensity μ and phase θ:

[0059]

[0060] where |m> denotes the m photon state. According to the assumption of protocol security, the phase θ of Alice and Bob's pulses is required to be randomized in the range of (0, 2π] and not published.

[0061] In the decoy-state MDI-QKD system based on phase post-selection provided in this embodiment, Alice and Bob at the light source end respectively send a series of strong reference pulses, and each strong reference pulse is followed by a signal pulse (signal pulse can be split from a strong reference pulse), then the states of the signal pulses of Alice and Bob can be expressed as:

[0062]

[0063]

[0064] where a and b represent Alice and Bob at the source end, j represents the time window of the jth pulse sent, γ represents the public phase related to the strong ...

Embodiment 2

[0082] This embodiment is applicable to a polarization encoding system.

[0083] The system consists of three parts: Alice, Bob and Charlie. Alice and Bob, as the sender, have the same structure and send pulses to the third party Charlie at the same time. As the measuring party, Charlie performs Bell state measurement on the received pulse pair, and Charlie can also be an untrustworthy eavesdropper (Eve).

[0084] The difference with Embodiment 1 is:

[0085] The Charlie detection structure adopts such as Figure 5 In the structure shown, the detection end includes an electrically controlled polarization controller respectively connected to each light source end, a beam splitter connected to two electrically controlled polarization controllers, and two polarization beam splitters connected to both beam splitters, Each polarizing beam splitter is connected to two independent single-photon detectors. Encoding modules can be used as Image 6 The Sagnac interferometer structur...

Embodiment 3

[0100] A decoy state MDI-QKD method based on phase post-selection, from the light source side, includes the following steps:

[0101] Modulate multiple strong reference pulses, and follow each strong reference pulse with a signal pulse of random intensity adjacently; keep the data under the measurement results of the effective response, and discard other data;

[0102] Carry out base vector comparison, retain the corresponding data when both light sources choose Z base vector, and obtain a string of bits for generating the original key, and other data are used for decoy state estimation;

[0103] Publish the signal pulse intensity when the Z base vector is not selected at both light source ends;

[0104] According to the published signal pulse strength, publish the private phase of the first decoy state pulse in the X base vector sent by both light source ends;

[0105] Select the signal pulse pairs that meet the set conditions in the private phase to form a subset,

[0106]...

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Abstract

The invention provides a decoy state MDI-QKD method and a decoy state MDI-QKD system based on phase post-selection. A light source end modulates a plurality of strong reference pulses and signal pulses. And the detection end measures the phase difference of the reference pulse pair, compensates the common phase difference of the signal pulse pair, carries out Bell state measurement, and publishes a measurement result. The light source ends reserve data under the measurement result of effective response, reserve corresponding data when the two light source ends select Z basis vectors, obtain a string of bits, publish signal pulse intensity under the condition that the two light source ends do not select the Z basis vectors and private phases for sending first decoy state pulses in X basis vectors, select signal pulse pairs meeting set conditions, and send the selected signal pulse pairs to the two light source ends; and estimating the phase flipping error rate of the single photon pair in the Z basis vector, and performing post-processing on the screened bit string based on the phase flipping error rate to obtain a final key. According to the method, the observation bit error rate under the X basis vector is closer to the bit error rate generated by a single photon state through a phase post-selection mode, and the observation bit error rate is enough true, so that the phase flipping bit error rate can be estimated more intensively, a higher key rate is obtained, and the security of a protocol is not influenced.

Description

technical field [0001] The invention belongs to the technical field of quantum secure communication, and in particular relates to a decoy state MDI-QKD method and system based on phase post-selection. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] Measurement device-independent quantum key distribution (MDI-QKD) system can defend against any side-channel attack at the detection end, and it is easy to combine with the decoy state method, which has broad application prospects. [0004] Improving the key rate of the decoy-state MDI-QKD system is of great significance for enhancing its practical value. The finite code length effect under the X base vector leads to an excessively large upper limit of the single photon phase inversion bit error rate, which is an important reason for restricting the key rate of the MDI-QKD system. For this rea...

Claims

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Application Information

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IPC IPC(8): H04L9/08
Inventor 王向斌姜聪
Owner JINAN INST OF QUANTUM TECH
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