We use the quantum correlations of twin-beams of light to probe the added noise when one of the beams propagates through a medium with anomalous dispersion. The experiment is based on two successive four-wave mixing processes in rubidium vapor, which allow for the generation of bright two-mode-squeezed twin-beams followed by a controlled advancement while maintaining the shared quantum-correlations between the beams. The demonstrated effect allows the study of irreversible decoherence in a medium exhibiting anomalous dispersion, and for the first time shows the advancement of a bright nonclassical state of light. The advancement and corresponding degradation of the quantum correlations are found to be operating near the fundamental quantum limit imposed by using a phase-insensitive amplifier.
@article{arxiv.1305.6614,
title = {Advanced Quantum Noise},
author = {Ulrich Vogl and Ryan T. Glasser and Jeremy B. Clark and Quentin Glorieux and Tian Li and Neil V. Corzo and Paul D. Lett},
journal= {arXiv preprint arXiv:1305.6614},
year = {2020}
}