Any quantum device that amplifies coherent states of a field while preserving their phase generates noise. A nonlinear, phase-invariant amplifier may generate less noise, over a range of input field strengths, than any linear amplifier with the same amplification. We present explicit examples of such nonlinear amplifiers, and derive lower bounds on the noise generated by a nonlinear, phase-invariant quantum amplifier.
@article{arxiv.cond-mat/9407011,
title = {Quantum Noise Limits for Nonlinear, Phase-Invariant Amplifiers},
author = {Dmitri Kouznetsov and Roberto Ortega and Daniel Rohrlich},
journal= {arXiv preprint arXiv:cond-mat/9407011},
year = {2009}
}
Comments
RevTeX, 6 pages + 4 figures (included in file; hard copy sent on request)