All Abstracts | Poster Abstracts | Talk Abstracts | Tutorial Abstracts

Time-Symmetric Quantum Smoothing: A General Theory of Optimal Quantum Sensing

Mankei Tsang, University of New Mexico

(Session 9 : Saturday from 4:30-5:00)

Abstract. In real-world sensing applications, the signal to be estimated, such as the position of an aircraft, a gravitational wave, or a magnetic field, is seldom a parameter constant in time but a fluctuating random process. Drawing insights from Bayesian estimation theory, I shall demonstrate how the optimal estimation of a random process coupled to a quantum sensor can be done using the recently proposed quantum smoothing theory. The theory calls for the use of not one but two density operators, one to be solved forward in time and one backward in time, and can out-perform conventional quantum filtering methods if delay is permitted in the estimation. Potential applications include gravitational wave sensing and atomic magnetometry. The accuracy improvement of quantum optical phase estimation due to smoothing has recently been experimentally demonstrated by an Australian-Japanese collaboration [Wheatley et al., arXiv:0912.1162].