Homodyne Estimation of Gaussian Quantum Discord
Rémi Blandino, Marco G. Genoni, Jean Etesse, Marco Barbieri, Matteo G. A. Paris, Philippe Grangier, Rosa Tualle-Brouri · Physical Review Letters · 2012
We address the experimental estimation of Gaussian quantum discord for a two-mode squeezed thermal state, and demonstrate a measurement scheme based on a pair of homodyne detectors assisted by Bayesian analysis, which provides nearly optimal estimation for small value of discord. In addition, though homodyne detection is not optimal for Gaussian discord, the noise ratio to the ultimate quantum limit, as dictated by the quantum Cramer-Rao bound, is limited to about 10 dB.