Phase stabilization with triple wavelength bands for single-photon interference in quantum communication

Optical interferometers are crucial for long-distance quantum communications. We propose a novel phase stabilization method employing triple wavelength bands for single-photon interference in optical fiber-based interferometers, incorporating a simplified laser frequency stabilization technique that utilizes a single nonlinear crystal. After stabilization, the residual phase noise of the fiber interferometer was 20 mrad for differential arm lengths (ΔL) of 0 and 10 m. This represents a 9-fold and 7.5-fold improvement for ΔL = 0 and 10 m, respectively, compared with those observed in previous double-wavelength methods. These findings enhance the visibility and simplicity of quantum key and entanglement distributions in long-distance quantum communication.