Synchronizing device for quantum key distribution (QKD) system

Abstract

The invention belongs to the technical field of quantum secret communication, and particularly discloses a synchronizing device for a quantum key distribution (QKD) system. The synchronizing device comprises a transmitting device for transmitting synchronizing light and signal light, a photoelectric conversion device, an adjustable time delay module, a single photon detector and a data processing module, and is characterized in that the frequency of the signal light sent by the transmitting device is much greater than the frequency of the synchronizing light, the frequency of the signal light is several times that of the synchronizing light, the synchronizing light and the signal light are transmitted in the same optical fiber, a low jitter frequency doubler is arranged between the photoelectric conversion device and the adjustable time delay module and is used for doubling the frequency of a synchronized electrical signal output by the photoelectric conversion device to be the same as the frequency of the signal light, and then outputting the signal, the adjustable time delay module uses the signal to generate a door control signal of the single photon detector with the same frequency of the signal light, and the data processing module uses the signal to finish subsequent processing. The synchronizing device can reduce the impact of the synchronizing light on the signal light, can guarantee normal door control signal of the detector, and can effectively improve the code rate of the QKD system.

Description

technical field [0001] The invention belongs to the technical field of quantum security communication, and in particular relates to a synchronization device for a QKD system. Background technique [0002] Quantum communication is currently recognized as a theoretically unconditionally secure communication method and has great application prospects. However, the low coding rate of quantum keys is an important factor restricting the application of quantum communication. Therefore, it is necessary to find ways to increase the coding rate. Generally, there are two methods: increasing the operating frequency of the quantum key distribution (QKD) system, and improving the detection efficiency of the single photon detector. Under the existing detection conditions, to increase the operating frequency of the QKD system requires the support of a corresponding synchronization system. [0003] The function of the synchronization system is to enable one-to-one correspondence between the...

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Problems solved by technology

[0006] In addition, since the synchronous light and the signal light are of the same frequency, if the coding rate of the QKD system is increased by increasing the luminous rate of the signal light, the rate increase will be limited due to the increased influence of the synchronous light on the signal light. Thereby restricting the improvement of the operating frequency of the QKD system

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