Observation of Quantum Noise Reduction on Twin Laser Beams
A. Heidmann, R. J. Horowicz, Serge Reynaud, E. Giacobino, Claude Fabre, G. Camy · Physical Review Letters · 1987
We have used a two-mode optical parametric oscillator operating above threshold to generate high-intensity twin beams which exhibit quantum correlations. The noise power measured on the intensity difference between two such beams is reduced by 30% below the shot-noise limit. Noise reduction is observed over a broad range of frequencies.