Polarization State Preparation and Control Integration of a Quantum Communication System Based on a Field- Programmable Gate Array

In quantum communication based on polarization encoding, the polarization state cannot be maintained for a long time because of the external temperature, stress, and defects in the optical fiber. This increases the bit error rate of the system. Therefore, polarization control is necessary to maintain robust operation of the communication system. Currently, decoy states are being widely used in quantum communication networks. Using decoy photons as a polarization reference, long-term and uninterrupted locking of the system polarization state can be achieved, and communication efficiency can be improved. In this study, an integrated polarization control system is built to control the polarization state preparation and single-photon transmission. The polarization state preparation unit, strong light polarization control unit, and single-photon polarization control unit are integrated into one system using a field-programmable gate array development board, which improves the integration of the system and makes system management more convenient. The experimental results show that the polarization state preparation unit can generate different polarization states as required, and the fidelity can reach 99. 11%+/- 0. 44% after strong light polarization and 97. 93% +/- 0. 96% after single-photon polarization control. These results demonstrate the effectiveness and stability of our proposed system.