Nonclassical Photon Correlations from Two-Level Atoms in AN Optical Cavity.

Hayato Goto, Kouichi Ichimura

S. L. Mielke, G. T. Foster, Luis A. Orozco

We report nonclassical correlations in the light transmitted by a collection of two-level atoms strongly coupled to a single mode of the electromagnetic field of a driven optical cavity. This cavity QED system can produce bunched light that violates the Schwarz inequality due to the state preparation of the system from the detection of a photon. The correlation function shows oscillations at a frequency that decreases with increasing intensity.

Robert J. Brecha, H. J. Carmichael

Harry J. Kimble

Patrick Hemphill, James Clemens

We calculate intensity autocorrelations and cross correlations for the light transmitted from a system consisting of a three-level Λ-type atom inside an optical cavity that supports two orthogonally polarized modes with one mode of the cavity weakly driven on resonance. We also include damping of the cavity modes and spontaneous emission from the atom using the framework of quantum trajectory theory. The correlation functions are compared with those of a two-level atom/cavity system as the coupling to the third level is increased, and we find a transition from photon bunching to photon antibunching. The three-level model allows the atom to couple to both field modes for which we calculate intensity cross correlations that exhibit nonclassical behaviors. Finally, we discuss the lack of entanglement between the field modes despite their common coupling to the same atom and the presence of atom-field entanglement.

C. Elliot Strimbu, Joseph Leach, Perry R. Rice

We consider intensity-field correlation functions for a two-level atom in a degenerate optical parametric oscillator (OPO), which would result from a conditioned homodyne measurement. Analytic results are obtained in the limit of weak driving fields using quantum trajectory methods for both the transmitted and fluorescent fields. This system is unique in that after detection of a photon, it is known that one excitation is in the system, in either the atom or cavity mode. We find large violations of inequalities satisfied by classical fields, for both transmitted and fluorescent fields. This is in contrast to the usual cavity QED system of an atom in a driven cavity where we do not find nonclassical behavior in the intensity-field correlation function in fluorescence. This is understood in terms of a relationship between the intensity-field correlation function and the second-order intensity correlation function, as well as the different amount of field-atom entanglement in the two systems. We show that for weak-field cavity QED one must have photon bunching to have nonclassical behavior in the intensity-field correlation function. We compare our results to those of an ordinary OPO. Finally, we also consider cross correlations, where we examine the transmitted (fluorescent) field conditioned by detection of a fluorescent (transmitted) photon.