Influence of a beam splitter on photon statistics

Abstract

The quantum analysis of the influence of a beam splitter on photodetection statistics is discussed. The link between second-order correlation functions and various experimental quantities obtained in photon counting and spectrum analysis is clarified. The introduction of a ``vacuum field'' is interpreted as a mathematical transformation between two sets of creation-annihilation operators, which can be used as a mathematical device for simplifying the calculations. However, its physical interpretation as a real field is shown to be potentially confusing. The present theoretical approach is used in the interpretation and the analysis of heterodyning experiments of a squeezed signal with a much stronger local oscillator in a coherent state.