Nonclassical Photon Correlations in Cavity QED

Abstract

Nonclassical photon correlations produced by two-level atoms interacting with a single mode of the electromagnetic field inside an optical resonator were first discussed several years ago within the context of the quantum theory of optical bistability. Specifically, photon antibunching (where the second-order intensity correlation function initially increases rather than decreases with time delay) was predicted in both the “good” cavity [cavity decay rate (2κ) ≪ atomic decay rates (γ ≪, γ ⊥)] and “bad” cavity (2κ ≫ γ ≪, γ ⊥) limits. The size of the effect was assumed to be very small, scaling inversely with the number of atoms N (bad cavity), or saturation photon number n_s (good cavity). It has recently become possible experimentally to consider a system in which these parameters are small (n_s ~ 1, N ~ 10 – 100) and therefore the nonclassical effects are quite large. In this paper we present theoretical results for a system on which experiments are currently in progress. We specifically emphasize the close relationship between results obtained for N > 1 atoms, and those found by Rice and Carmichael for a single atom interacting with a cavity mode.