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

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 ⁸⁷Rb with a non-degenerate four-wave-mixing process in a double-lambda configuration in a ⁸⁵Rb 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 ⁰ = 2 transition of ⁸⁷Rb.