title: Four-wave mixing and biphoton generation in a two-level system.
abstract: We find that in a two-level system there are two kinds of four-wave mixing processes which destructively contribute to the third-order nonlinear susceptibility. In a paired-photon generation scheme by using a single retroreflected pump beam, these two processes occur with definite time orders. The biphoton temporal correlation, which is measured with a back-to-back geometry in a laser-cooled two-level atomic ensemble, shows a damped Rabi oscillation and photon antibunching. Without suppressing the background of Rayleigh scattering, the upper limit of Cauchy criteria is estimated.
authors.affiliation: Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA. dus@stanford.edu
authors.forename: Shengwang
authors.initials: S
authors.lastname: Du
authors.forename: Jianming
authors.initials: J
authors.lastname: Wen
authors.forename: Morton H
authors.initials: MH
authors.lastname: Rubin
authors.forename: G Y
authors.initials: GY
authors.lastname: Yin