Dynamics and quantum noise in photon-photon scattering

Summary form only given. Processes such as self-focusing and degenerate four-wave mixing, which classically can be described in terms of an intensity-dependent refractive index (the optical Kerr effect), appear at the microscopic level to involve momentum exchange among photons, as if there were a photon-photon interaction potential. Within this picture, Kerr optical systems are collections of weakly interacting Bose particles and can be used to investigate a number of interesting problems in condensed matter physics. The nonlinear Schrodinger equations which describe both temporal and spatial solitons are formally equivalent to second quantized /spl phi//sup 4/ field theories. To determine the domain of validity of this analogy, we consider the similarities and differences between an effective photon-photon interaction potential and the atom-mediated photon-photon interaction near the D2 resonance in rubidium vapor. The photon-photon interaction is characterized in terms of scattering amplitudes, and the duration of the photon-photon interaction is shown to depend in an essential way upon inhomogeneous broadening. We present the results of experimental measurements on large-angle photon-photon scattering in a colliding-wave geometry in rubidium vapor. In particular, angular and time correlations are compared to theory. Connections to the theory of quantum noise in phase conjugate reflection are explored.