We report the first experimental demonstration of conditional preparation of a non classical state of light in the continuous variable regime. Starting from a non degenerate OPO which generates above threshold quantum intensity correlated signal and idler "twin beams", we keep the recorded values of the signal intensity only when the idler falls inside a band of values narrower than its standard deviation. By this very simple technique, we generate a sub-Poissonian state 4.4dB below shot noise from twin beams exhibiting 7.5dB of noise reduction in the intensity difference.
@article{arxiv.quant-ph/0304111,
title = {Conditional preparation of a quantum state in the continuous variable regime: generation of a sub-Poissonian state from twin beams},
author = {Julien Laurat and Thomas Coudreau and Nicolas Treps and Agnes Maitre and Claude Fabre},
journal= {arXiv preprint arXiv:quant-ph/0304111},
year = {2009}
}