Single mode quadrature entangled light from room temperature atomic vapour

TL;DR

This paper demonstrates a robust method to generate narrow-band, quadrature entangled light at room temperature using atomic vapour, suitable for quantum information applications.

Contribution

It introduces a novel mechanism for squeezing and entangling light via correlated scattering in atomic vapour, with an experimental demonstration at room temperature.

Findings

Achieved 3.5 dB pulsed frequency nondegenerate squeezing

Generated entangled modes separated by Zeeman frequency

Produced narrow-band squeezed light compatible with quantum protocols

Abstract

We analyse a novel squeezing and entangling mechanism which is due to correlated Stokes and anti-Stokes photon forward scattering in a multi-level atom vapour. Following the proposal we present an experimental demonstration of 3.5 dB pulsed frequency nondegenerate squeezed (quadrature entangled) state of light using room temperature caesium vapour. The source is very robust and requires only a few milliwatts of laser power. The squeezed state is generated in the same spatial mode as the local oscillator and in a single temporal mode. The two entangled modes are separated by twice the Zeeman frequency of the vapour which can be widely tuned. The narrow-band squeezed light generated near an atomic resonance can be directly used for atom-based quantum information protocols. Its single temporal mode characteristics make it a promising resource for quantum information processing.