Quantum key distribution system based on B92 protocol

Abstract

The invention discloses a quantum key distribution system based on a B92 protocol. A sending end comprises a pulse laser, an intensity modulator, a circulator, a polarization beam splitter, a phase modulator and an adjustable attenuator. The polarization beam splitter and the phase modulator are connected through a polarization maintaining optical fiber to form a Sagnac annular structure. A receiving end comprises a polarization-maintaining beam splitter, a first polarization controller, a second polarization controller, an optical fiber extension cord, a polarization beam combiner and a single-photon detector, and the input end of the polarization-maintaining beam splitter is connected with the adjustable attenuator of the sending end through a polarization-maintaining optical fiber. Compared with the prior art, the invention discloses a quantum key distribution system based on a B92 protocol. The sending end can generate two polarization states required by a B92 protocol only by a single photon source and a phase modulator, and the phase modulator only needs to randomly switch between a voltage application state and a non-voltage application state, so that the complexity and thecost of the system are greatly reduced compared with a multi-laser structure of a traditional polarization coding QKD system.

Description

technical field [0001] The invention relates to the technical field of quantum polarization encoding, in particular to a quantum key distribution system based on the B92 protocol. Background technique [0002] Cryptography plays a vital role in various fields. With the advancement of technology, especially the threat of quantum computers, classical cryptography based on computational complexity will face unprecedented challenges. The quantum key distribution technology guarantees its unconditional security by the basic principle of quantum mechanics, combined with the one-time pad symmetric encryption system, it can meet people's growing demand for secure communication. In a channel with excellent performance, the B92 protocol is close to the BB84 protocol in terms of security, but it is relatively simple in terms of quantum state modulation and demodulation and system complexity, so it is easier to implement. [0003] The two polarization states commonly used in the polari...

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Problems solved by technology

Therefore, the system has the disadvantages of large volume, high cost and complex system.

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