Squeezed light generation by four-wave mixing near an atomic resonance.

Squeezed light generated by four-wave mixing near the Na atomic resonance is compared with a full quantum theoretical model. Losses and dephasing due to spontaneous emission near the atomic resonance are included in this theoretical treatment. The experimental results show noise reduction greater than 1dB below the standard quantum limits and are in good agreement with the quantum model at low pump intensities and large detuning. The theory and experiment show that limits to squeezed light noise reduction due to spontaneous emission losses can be largely avoided by using nondegenerate four-wave-mixing and pump intensities near the atomic saturation values.