We report on the experimental demonstration of strong quadrature EPR entanglement and squeezing at very low noise sideband frequencies produced by a single type-II, self-phase-locked, frequency degenerate optical parametric oscillator below threshold. The generated two-mode squeezed vacuum state is preserved for noise frequencies as low as 50 kHz. Designing simple setups able to generate non-classical states of light in the kHz regime is a key challenge for high sensitivity detection of ultra-weak physical effects such as gravitational wave or small beam displacement.
@article{arxiv.quant-ph/0403224,
title = {Compact Source of EPR Entanglement and Squeezing at Very Low Noise Frequencies},
author = {Julien Laurat and Thomas Coudreau and Gaelle Keller and Nicolas Treps and Claude Fabre},
journal= {arXiv preprint arXiv:quant-ph/0403224},
year = {2009}
}