Quantum key distribution method and system based on orbital angular momentum encoding

Abstract

The invention provides a quantum key distribution method and system based on orbital angular momentum encoding. An orbital angular momentum entangled state is used as an information encoding carrier at a quantum key encoding transmitting terminal; orbital angular momentum is dynamically modulated through a spatial light modulator, and stable quantum codes are output; received quantum information can be stably and quickly measured at a receiving terminal through the spatial light modulator and a coincidence counting measurer, and by comparing encoding bases and measuring bases on a public channel, quantum bit code information is accurately decoded. The quantum key modulating and demodulating process is highly functionally integrated, information can be conveniently transmitted and received in real time, the system is efficient and stable, tapping behaviors of tappers can be judged in real time by violation verification of a Bell-CHSH inequation, and high-security quantum key distribution is guaranteed.

Description

technical field [0001] The invention relates to the technical field of quantum cryptography and optical communication, in particular to a quantum key distribution method and system based on orbital angular momentum encoding. Background technique [0002] Quantum key distribution systems are often used to load quantum encoded information with physical quantities such as polarization and phase. In the quantum key distribution system based on polarization encoding, the quantum information is encoded on the polarization state of the photon. The polarization state usually needs to be modulated by electro-optic crystals such as lithium niobate. Due to the high half-wave voltage modulation requirements of electro-optic crystals, therefore It is very limited in actual use. On the other hand, electro-optic crystals still have the problem of low modulation rate, which further affects the coding rate of quantum key distribution. In addition, during the transmission of quantum signals...

AI Technical Summary

Problems solved by technology

At present, a quantum key distribution scheme based on single-photon orbital angular momentum has been reported. This scheme improves the utilization efficiency of photons and the security of the system by using the orthogonal characteristics of different orders of orbital angular momentum to encode and decode information. , however, at the encoding transmitter end, the encoding information needs to rely on two lasers that can emit photons carrying different orbital angular momentum. Due to the constraints of orbital angular momentum generation technology, the generation efficiency of such photons is not high, and it is difficult to achieve a single The level of photons, which leads to an increase in the bit error rate of the system, and there is a risk of being eavesdropped by eavesdroppers. In addition, a Mach-Zehnder interferometer is also required at the decoding end, which also increases its communication capabilities. application difficulty

A quantum key distribution system based on spin-orbit angular momentum hybrid modulation has also been reported, which uses the mixed spin-orbit angular momentum entangled photon pairs as the carrier of the encoded information, and uses the coincidence measurement unit as the information carrier The decoding device improves the security of the system. However, the core device q-plate of the hybrid entangled light source is still in the research and development stage of the laboratory. system application, in addition, at the demodulation end of the system, since the coincidence characteristic curve of its decoding is a continuous curve, a small deviation of the coincidence count will bring a high bit error rate, due to the difference between the information sender and the receiver Without a communication channel for communication, this part of error information will not be effectively eliminated

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