The estimation of signal force parameters in quantum variation measurement

Sergey P. Vyatchanin

Abstract It is shown by examples that the procedure of a quantum variation measurement allows one to estimate simultaneously several parameters of the signal force (amplitude, arrival time, frequency) with errors much less than the standard quantum limit.

Sergey P. Vyatchanin, Elena A. Zubova

A. M. Sinev

We consider a solvable model of a laser-interferometer measuring a weak classical force. The model takes into account dissipation of the energy by transfer to the environment at zero temperature. The sensitivity (the signal-to-noise ratio) of the device is defined as the corresponding ratio between the mean value and the variance of a certain observable. We analyze the dependence of the sensitivity upon the duration of the measurement and the photon number. For parameters typical for the LIGO project, we discuss numerical estimates.

M. Luanshi, M. B. Malyutov

M. E. Goggin, Holger Friedrich Hofmann, Marcelo Pereira de Almeida +1 more

Frank Verstraete, Andrew C. Doherty, Hideo Mabuchi

We present a general framework for sensitivity optimization in quantum parameter estimation schemes based on continuous (indirect) observation of a dynamical system. As an illustrative example, we analyze the canonical scenario of monitoring the position of a free mass or harmonic oscillator to detect weak classical forces. We show that our framework allows the consideration of sensitivity scheduling, as well as estimation strategies for nonstationary signals, leading us to propose corresponding generalizations of the standard quantum limit for force detection.