Optimal quantum estimation of loss in bosonic channels

Abstract

We address the estimation of the loss parameter of a bosonic channel probed by Gaussian signals. We derive the ultimate quantum bound on precision and show that no improvement may be obtained by having access to the environment degrees of freedom. We found that, for small losses, the variance of the optimal estimator is proportional to the loss parameter itself, a result that represents a qualitative improvement over the shot noise limit. An observable based on the symmetric logarithmic derivative is derived, which attains the ultimate bound and may be implemented using Gaussian operations and photon counting.

4 pages, 2 figures, replaced with published version

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• Optimal phase measurements with pure Gaussian states
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Cited by in corpus (6)

• Quantum criticality as a resource for quantum estimation
• Optimal estimation of losses at the ultimate quantum limit with non-Gaussian states
• An operational interpretation for multipartite entanglement
• Squeezed vacuum as a universal quantum probe
• Bayesian estimation in homodyne interferometry
• Optimal estimation of entanglement