Propagation of quantum optical fields under the conditions of multi-photon resonances in a coherent atomic vapor

Abstract

We experimentally investigate a weak optical probe pulse propagation under the EIT conditions through a hot Rb vapor cell, and analyze the quantum noise modification resulting from interaction with atoms. We focus on understanding the sources of excess noise, observed after the EIT vapor cell in the case of both squeezed vacuum and coherent optical probe fields. We show that a small non-zero average amplitude of the probe field (due to imperfect polarization filtering) gives rise to a phase-sensitive excess quantum noise that grows with atomic density.