Homodyne estimation of Gaussian quantum discord

Rémi Blandino (1) , Marco G. Genoni (2) , Jean Etesse (1) , Marco Barbieri (1) , Matteo G. A. Paris (3) , Philippe Grangier (1) , Rosa Tualle-Brouri (1)

1 Laboratoire Charles Fabry / Optique Quantique
2 Quantum Optics and Laser Science, Blackett Laboratory
3 Dipartimento di Fisica (Milano)

We address the experimental estimation of Gaussian quantum discord for two-mode squeezed state, and demonstrate a measurement scheme based on a pair of homodyne detectors assisted by Bayesian analysis. Our scheme provides nearly optimal estimation for small value of discord, where Bayesian analysis allows to greatly improves performances. Besides, though homodyne detection is not optimal for Gaussian discord, the noise ratio to the ultimate quantum limit is limited to about 10 dB. Our results illustrate how suitable data processing can decrease significantly the uncertainty when optimal detection schemes are not available.

Domaines: Physique Quantique [quant-ph]

Rémi Blandino, Marco G. Genoni, Jean Etesse, Marco Barbieri, Matteo G. A. Paris, et al.. Homodyne estimation of Gaussian quantum discord. 2012. ⟨hal-00676458v1⟩