Photon statistics for two-state atoms in an optical cavity

Abstract

While for the most part quantum statistical processes in quantum optics are investigated in a weak-coupling regime, it has recently become possible to realize experimentally systems for which the internal coupling coefficient g is comparable to the external dissipative rates. Within this context the subject of our investigation is the quantum dynamical processes for a collection of N two-state atoms strongly coupled to a single mode of a high finesse optical cavity. Our particular system consists of a collection of N~20 Cesium atoms (6S 1/2, f = 4– > 6P 3/2, f = 5 transition at 852 nm) interacting with the TEMoo mode of a spherical mirror cavity of finesse 4 × 104. Of principal importance are the single atom cooperativity parameter C1 = g 2/κγ and the saturation photon number no = g2/8γ 2, where (κ,γ) are the cavity and atomic decay rates. For our system, c1~1 and n0~0.5. In measurements of the joint probability of photoelectric detection we observe photon antibunching and sub-Poissonian photon statistics.1,2 An interpretation of our results in terms of quantum state reduction and interference in a dissipative dynamical setting is presented.2 We emphasize the decisive role played by the quantum fluctuations of a single atom (c1~1), which can result in a field of large variance even in the presence of N>1 atoms.