Improved passive decoy state QKD (quantum key distribution) system based on attenuation laser light source

Abstract

The invention discloses an improved passive decoy state QKD (quantum key distribution) system based on an attenuation laser light source. Two independent phase-randomized weak coherent light beams areused for interference on a beam splitter, and output of the beam splitter serves as signal light and idle light which are transmitted to a receiving end and used for local detection. An adjustable beam splitter VBS and two detectors are added at a local detection position of a transmitting end, four different response events are generated after the idle light passes the VBS, and the four different response events are recorded and used for estimating and processing signals received by the receiving end. The transmitting end can acquire four different response events only by the aid of an attenuation light source and a standard linear optical element, more decoy states can be acquired, a compact estimation method is used, and various parameters of a key extraction ratio formula are effectively estimated. The different response events of the transmitting end are classified, more input parameters are acquired, and post-processing of the receiving end is facilitated to increase key extraction ratio and transmission distance.

Description

technical field [0001] The invention belongs to the technical field of quantum information, and in particular relates to an attenuated laser light source, which is suitable for application fields such as quantum communication and quantum cryptography. technical background [0002] Based on the theory of quantum mechanics, Quantum Key Distribution (Quantum Key Distribution, QKD) can send keys between legal communication parties in an unconditional and secure manner, and combined with the one-time pad algorithm in modern cryptosystems, it can achieve unconditional security. Confidential Information Transmission. But in fact, due to the unsatisfactory light sources, equipment, transmission channels, etc., the absolute security endowed by quantum mechanics cannot be realized. Aiming at this situation, many different protocols and methods have been proposed, such as decoy state method, device-independent quantum key distribution (DI-QKD), measurement device-independent quantum k...

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Problems solved by technology

However, these schemes have some shortcomings: when using the multi-intensity decoy state scheme, the sending end of the legal user has to randomly modulate the signal pulse light to different intensities by using an intensity modulator, which inevitably introduces a difference in the optical signal intensity. Uncertainty, which in turn leads to the decline of quantum key extraction rate and transmission distance, and in fact it is difficult to achieve truly random modulation of light intensity

As for the passive decoy state method proposed by Curty et al., since the receiving end only has two kinds of response events, trigger and non-trigger, and the input parameters are few, the estimation of the response rate and bit error rate of legitimate users to single photons is very rough, and finally The overall performance of the actual QKD system is poor

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