Quantum theory of radiation-pressure fluctuations on a mirror

Abstract

The quantum-mechanical operators that represent the radiation pressure on a perfect mirror are determined. It is shown that these operators reproduce the known forms of the mean and the variance of the Casimir force from the vacuum field on a perfect mirror when a suitable time average is taken. The mean and the variance of the radiation pressure are increased in the presence of an incident light beam. These quantities are determined here for optical pulses of coherent, chaotic, and number-state light, again with suitable time averaging to take into account the measurement process. It is found that the increase in mean pressure is the same for the different kinds of light, but that the variances found for chaotic and number-state light are, respectively, greater and smaller than the variance for coherent light.