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arXiv · 1511.06650

Estimation of covariance matrix of macroscopic quantum states

László Ruppert·Vladyslav C. Usenko·Radim Filip
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Abstract

For systems analogous to a linear harmonic oscillator, the simplest way to characterize the state is by a covariance matrix containing the symmetrically-ordered moments of operators analogous to position and momentum. We show that using Stokes-like detectors without direct access to either position or momentum, the estimation of the covariance matrix of a macroscopic signal is still possible using interference with a classical noisy and low-intensity reference. Such a detection technique will allow to estimate macroscopic quantum states of electromagnetic radiation without a coherent high-intensity local oscillator. It can be directly applied to estimate the covariance matrix of macroscopically bright squeezed states of light.

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László Ruppert, Vladyslav C. Usenko, Radim Filip. 2016-05-24. Estimation of covariance matrix of macroscopic quantum states. https://doi.org/10.1103/physreva.93.052114

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