Atomic resonant single-mode squeezed light from four-wave mixing through feedforward.

Abstract

Squeezed states of light have received renewed attention due to their applicability to quantum-enhanced sensing. To take full advantage of their reduced noise properties to enhance atomic-based sensors, it is necessary to generate narrowband near or on atomic resonance single-mode squeezed states of light. We have previously generated bright two-mode squeezed states of light, or twin beams, that can be tuned to resonance with the D1 line of Rb87 with a non-degenerate four-wave-mixing process in a double-lambda configuration in a Rb85 vapor cell. Here, we report on the use of feedforward to transfer the amplitude quantum correlations present in the twin beams to a single beam for the generation of single-mode amplitude squeezed light. With this technique, we obtain a single-mode squeezed state with -2.9±0.1 dB of squeezing when tuned off resonance and -2.0±0.1 dB when tuned on resonance with the D1 F=2 to F'=2 transition of Rb87.