A quanta secret key distribution system for phase coding polarization detection

Abstract

This invenion discloses a distribution system for quantum ciphered keys testing polarization of phase coding, in which, a transmitting party is connected with a receiving party by a quantum channel and either of which includes a same polarized beam splitting and merging device with four ports, the reflection port of which is connected with a phase modulator and a 90deg. rotation Faraday mirror orderly to form a long circuit and a transmission port of which is conneted with the 90deg. rotation Faraday mirror to form a short circuit, the incident port of the beam splitting and merging device is connected with a single photon source and the exit port is connected to a common port of a lambda/2 wave plate and a three-port polarized splitting/merging device, the reflection and the transmission ports of which are connected with a single-photon detector.

Description

technical field [0001] The invention relates to the technical field of optical transmission secure communication, in particular to a quantum key distribution system. Background technique [0002] Quantum information science is the product of the combination of quantum mechanics and information science, and it is an emerging frontier science that will have a significant impact on human society. Quantum key distribution is an important branch of quantum information science, and it is also the closest practical field in current quantum information. In 1992, based on the BB84 protocol, Bennett et al. used strongly attenuated laser pulses as a single photon source, and the information was loaded on the polarization of the single photon. For the first time, they successfully completed a demonstration experiment in free space, thus setting off a quantum key The culmination of assigned experimental research. U.S. Patent No. 5307410 proposes a quantum key distribution system based ...

AI Technical Summary

Problems solved by technology

However, the disadvantage of this scheme is: using an ideal single photon source, since the light pulse needs to go back and forth twice in the quantum channel, the limit communication distance is only half of the one-way transmission

The usual method for this solution is to use strong light when going out, and attenuate it into a single photon source when returning. However, the return loss in the optical path increases the bit error rate, and it cannot effectively prevent Trojan horse attacks.

Chinese patent application number: 200410013996.6 Invention name: "A polarization control encoding method, encoder and quantum key distribution system" proposes a quantum key distribution system with a polarization control encoder as the core, due to the security of both parties in the communication The ordinary X-type coupler used in the zone, the random selection of the single photon path will cause a decrease in efficiency

In addition, the above-mentioned various methods all use phase encoding and coherent detection schemes. In addition to the above-mentioned deficiencies, this scheme also has a single encoding method and detection method, which limits the development of quantum key distribution technology.

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