Strong low-frequency quantum correlations from a four-wave-mixing amplifier
Colin F. McCormick, Alberto M. Marino, Vincent Boyer, Paul D. Lett · Physical Review A · 2008
Using a simple scheme based on nondegenerate four-wave mixing in a hot vapor, we generate bright twin beams which display a quantum noise reduction in the intensity difference of more than $8\phantom{\rule{0.3em}{0ex}}\mathrm{dB}$. The absence of a cavity makes the system immune to external perturbations, and strong quantum noise reduction is observed at frequencies as low as $4.5\phantom{\rule{0.3em}{0ex}}\mathrm{kHz}$ and over a large frequency range.