Versatile Gaussian probes for squeezing estimation

Rigovacca, Luca; Farace, Alessandro; Souza, Leonardo A. M.; De Pasquale, Antonella; Giovannetti, Vittorio; Adesso, Gerardo

Abstract

We consider an instance of “black-box” quantum metrology in the Gaussian framework, where we aim to estimate the amount of squeezing applied on an input probe, without previous knowledge on the phase of the applied squeezing. By taking the quantum Fisher information (QFI) as the figure of merit, we evaluate its average and variance with respect to this phase in order to identify probe states that yield good precision for many different squeezing directions. We first consider the case of single-mode Gaussian probes with the same energy, and find that pure squeezed states maximize the average quantum Fisher information (AvQFI) at the cost of a performance that oscillates strongly as the squeezing direction is changed. Although the variance can be brought to zero by correlating the probing system with a reference mode, the maximum AvQFI cannot be increased in the same way. A different scenario opens if one takes into account the effects of photon losses: coherent states represent the optimal single-mode choice when losses exceed a certain threshold and, moreover, correlated probes can now yield larger AvQFI values than all single-mode states, on top of having zero variance.

Citation

Rigovacca, L., Farace, A., Souza, L. A. M., De Pasquale, A., Giovannetti, V., & Adesso, G. (in press). Versatile Gaussian probes for squeezing estimation. Physical Review A, 95(5), Article 052331. https://doi.org/10.1103/PhysRevA.95.052331

• Journal Article Type: Article
• Acceptance Date: Apr 27, 2017
• Online Publication Date: May 16, 2017
• Deposit Date: May 19, 2017
• Publicly Available Date: May 19, 2017
• Journal: Physical Review A
• Print ISSN: 2469-9926
• Electronic ISSN: 2469-9934
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 95
• Issue: 5
• Article Number: 052331
• DOI: https://doi.org/10.1103/PhysRevA.95.052331
• Public URL: https://nottingham-repository.worktribe.com/output/860564
• Publisher URL: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.95.052331
• Additional Information: Versatile Gaussian probes for squeezing estimation, ; Luca Rigovacca, Alessandro Farace, Leonardo A.M. Souza, Antonella De Pasquale, Vittorio Giovannetti, and Gerardo Adesso, Phys. Rev. A 95, Iss. 5, May 2017, 052331.