Delay of squeezing and entanglement using electromagnetically induced transparency in a vapour cell

Abstract

We demonstrate experimentally the delay of squeezed light and entanglement using Electromagnetically Induced Transparency (EIT) in a rubidium vapour cell. We perform quadrature amplitude measurements of the probe field and find no appreciable excess noise from the EIT process. From input squeezing of 3.2±0.5 dB at low sideband frequencies, we observed the survival of 2.0±0.5 dB of squeezing at the EIT output. By splitting the squeezed light on a beam-splitter, we generated biased entanglement between two beams. We transmit one of the entangled beams through the EIT cell and correlate the quantum statistics of this beam with its entangled counterpart. We experimentally observed a 2.2±0.5μs delay of the biased entanglement and obtained a preserved degree of wavefunction inseparability of 0.71±0.01, below the unity value for separable states.