Quantum Key Distribution System Immune to Polarization-Induced Signal Fading with Quarter-Wave Plate Reflector-Michelson Interferometers.

Improvement of QKD performance, particularly on system stability, has been required to meet practical application. In this letter, we design a quarter-wave plate reflector-Michelson interferometer based one-way intrinsic-stabilization QKD system. By introducing quarter-wave plate reflector-Michelson interferometers, with the long and short arms comprising of polarization maintaining optical fiber, quarter-wave plate and total reflector, the QKD system can be free of polarization disturbances caused by quantum channel and optical devices in the system. The experimental result shows that the QKD system has long-term low quantum bit error rate, and the safe key rate is about 7.34 kbps over 50.4 km standard optical fiber in the lab.