Photon Noise Reduction Using Active Control with Twin Beams Generated by AN Optical Parametric Oscillator

Jerome C. Mertz, A. Heidmann, Claude Fabre

We present a general theory for intensity noise reduction when one beam of light is used to control another. We use a semiclassical input-output formalism and determine the conditions necessary for noise reduction below the shot-noise level. Configurations are examined where the intensity of one beam is monitored and control is effected directly to the other beam (feedforward), or indirectly through the beam source (feedback). The results are applied to the case of twin beams generated by an optical parametric oscillator. We detail for this system the implementation of an electro-optic control channel. Finally, a comparison is made between theory and experiment.

E. Giacobino, Claude Fabre, A. Heidmann +2 more

Jerome C. Mertz

We present two experiment that demonstrate intensity noise reduction in light below the standard quantum noise level. A first experiment establishes a reduction of 86 % in the intensity difference noise spectrum of twin beams generated by an Optical Parametric Oscillator. The second experiment exploits this intensity correlation between the twin beams and uses one beam to electro-optically control the other, generating a single beam whose intensity noise is reduced 24 % below the shot noise level. General theories are presented for both processes using a semi-classical input-output formalism. Control configurations are examined where the noise reduction is effected directly from one beam to the other (feedforward), or indirectly through the pump beam (feedback). We determine the maximum amount of noise reduction that may be obtained from active control and detail for these configurations the limitations imposed by constraints of causality and stability. Finally, we demonstrate the equivalence of the semi-classical model with a "corpuscular" photon model in the small fluctuation limit, which we substantiate using Monte-Carlo simulation.

A. Heidmann, Jerome C. Mertz, Claude Fabre +2 more

Jerome C. Mertz, Thierry Debuisschert, A. Heidmann +2 more

We report an observed quantum noise reduction of 86% (8.5 dB) near 3 MHz in the intensity difference between the twin beams generated by a nondegenerate type II optical parametric oscillator operating above threshold.

Miguel Orszag, J. C. Retamal