Quantum Noise Reduction by Photodetection with Feedback
Gerard J Milburn · Journal of Modern Optics · 1991
A simple model is proposed to account for the generation of sub-shot noise light by feedback of the photocurrent. The model is based on a variable beam splitter controlled by the photocurrent from a detector placed after the beam splitter. The zero-feedback transmittivity is not necessarily unity. The field transmitted by the beam splitter shows reduced photon noise when the feedback causes a decreasing transmittivity.