title: Phase estimation via quantum interferometry for noisy detectors.
abstract: The sensitivity in optical interferometry is strongly affected by losses during the signal propagation or at the detection stage. The optimal quantum states of the probing signals in the presence of loss were recently found. However, in many cases of practical interest, their associated accuracy is worse than the one obtainable without employing quantum resources (e.g., entanglement and squeezing) but neglecting the detector's loss. Here, we detail an experiment that can reach the latter even in the presence of imperfect detectors: it employs a phase-sensitive amplification of the signals after the phase sensing, before the detection. We experimentally demonstrated the feasibility of a phase estimation experiment able to reach its optimal working regime. Since our method uses coherent states as input signals, it is a practical technique that can be used for high-sensitivity interferometry and, in contrast to the optimal strategies, does not require one to have an exact characterization of the loss beforehand.
authors.affiliation: Dipartimento di Fisica, Sapienza Università di Roma, piazzale Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Nicolò
authors.initials: N
authors.lastname: Spagnolo
authors.forename: Chiara
authors.initials: C
authors.lastname: Vitelli
authors.forename: Vito Giovanni
authors.initials: VG
authors.lastname: Lucivero
authors.forename: Vittorio
authors.initials: V
authors.lastname: Giovannetti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Maccone
authors.forename: Fabio
authors.initials: F
authors.lastname: Sciarrino
mesh_terms: D007368:Interferometry / Q000379:methods*; D008962:Models, Theoretical; D011789:Quantum Theory; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio