Vibrational noise removal method for the multi-photon interferometer of an optical loop system

Multi-photon interference effects of the optical loop in a double-Lambda/V system aid coherent photon control, especially all-optical switching between single photons. In the multi-photon interference, phase fluctuations induced by the mechanical vibration of the optical components should be removed to observe the high fidelity of photon controls. We solved this problem by overlapping coupling and probe beams that have opposite phase shifts in the optical loop system to cancel out phase fluctuation induced by mechanical vibration. We used two independent laser sources to generate two pairs of coupling-probe fields that are resonant on a double-Lambda system. The removal of vibrational phase fluctuation was confirmed by comparison with a normal phase-dependent light-switching experiment.