Feasible phase detection with ideal sensitivity

Abstract

We present a first feasible scheme for detecting the phase of a single mode of radiation with ideal RMS sensitivity N n 1 versus the average number of photons N n .I t involves pairs of alternate independent homodyne measurements of two conjugated quadratures on a weakly squeezed state at the input. Nonunit quantum efficiency of photodetectors degrades phase sensitivity leading to a power law N n ./ , with increasing versus . In phase-sensing interferometers minute variations of environmental parameters are detected through changes in the phase shift of a light beam relative to a local oscillator (LO). The back-action effect of radiation pressure on the measured parameter poses the problem of optimizing phase sensitivity for a given average number of photons N