Generation and Waveform Control of Narrow Bandwidth Paired Photons - Pavel Kolchin

In the course of time spontaneous parametric down-conversion in nonlinear crystals has become the near-standard method of generating correlated and entangled photon pairs. The existing paired photon sources based on crystals suffer from broad linewidth, short coherence time and low spectral brightness. Recently a new approach to generation of paired photons with long coherence time has been demonstrated by the groups of M. Lukin and J. Kimble. They used EIT to generate single photons on demand and to show non-classical correlations of paired photons. More recently, S. Harris research group demonstrated generation and rudimentary waveform shaping of narrow-band biphotons with high spectral brightness. In this talk, I will give an overview of experiments and theory done at Stanford on narrow-band paired photon generation using cold Rb atoms. I analyze different regimes of parametric down-conversion and discuss the influence of the optical depth of the atomic sample and Langevin noise fluctuations on the process. I also discuss the way to control the shape of generated paired photons and outline the ways to improve the paired photon source.