Encoder and decoder for quantum cryptographic communication

Abstract

The invention provides an encoder and decoder for quantum cryptographic communication. The encoding and decoding functions of a BB84 protocol can be achieved through the encoder and the decoder. According to the encoder and decoder for quantum cryptographic communication, an optical switch device is used at a transmitting terminal, so that optical pulse passes through a plurality of interferometers randomly, the phase differences between long arms and short arms of the interferometers are k*2phi+phi / 2 sequentially, and therefore the encoding function required by the BB84 protocol is achieved; a measurement base is randomly selected in a passive mode through an optical beam splitter at a receiving terminal and the decoding function is achieved through the interferometers with the phase differences of the long arms and the short arms to be k*2phi+phi / 2. Due to the adoption of the interferometers, high-speed phase modulators do not need to be used in the interferometers, the limit to speed by round-trip time is broken, a phase modulation drive circuit can be obtained through devices according to a low-speed design scheme, the difficulty in achieving a high-speed quantum cryptographic communication system is greatly reduced, and the encoder and the decoder are quite suitable for achieving high-speed quantum cryptographic communication. If the structure of the Michelson interferometer (F-M) with a Faraday reflector adopted is used, the self-adaptation compensation capacity for dealing with polarization disturbance in an optical path is further achieved.

Description

technical field [0001] The invention belongs to the technical field of quantum cryptography communication, in particular to an encoder and a decoder for quantum cryptography communication. Background technique [0002] Quantum cryptography communication combines the principles of quantum physics and modern communication technology. Quantum cryptography communication uses physical principles to ensure the security of the remote key negotiation process and results. Combined with the "one-time pad" encryption technology, it can realize secure communication that does not depend on the complexity of the algorithm. [0003] At present, quantum cryptography mainly uses photons as the realization carrier, and distributes them through free space or fiber optic channels. Classical random bits are loaded onto physical quantities such as polarization and phase of photons by means of polarization encoding and phase encoding. Nowadays, optical fiber communication has become the infrastr...

AI Technical Summary

Problems solved by technology

[0005] (1) It is required that photons whose polarization states are perpendicular to each other can be transmitted in the phase modulator with low loss, while most of the phase modulators used in applications such as conventional optical communications only allow a single polarization state to pass through, and the polarization state perpendicular to it is among them Transmission will have a large loss, so special requirements are put forward for the design process and implementation technology of the phase modulator;

[0006] (2) High-bandwidth electro-optical phase modulation devices generally need to be matched with low-impedance resistors, so the drive circuit is required to provide a large drive current, and long-term work may generate heat, which will affect system stability;

[0007] (3) In order to modulate the photons to obtain a stable and precise phase, the modulation drive voltage needs to be kept stable at the moment when the photons arrive, and the round-trip structure will prolong this time, which may limit the improvement of the system working rate;

[0009] (5) Both the transceiver and the transmitter need to actively control the phase. Therefore, both the transmitter and receiver need to have a true random number drive source

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