On Wed 31 May, 14.00, Auletta Ottica Quantistica (piano 5 LITA), Matteo Bina will deliver a talk about
Continuous-variable quantum probes for structured environments
We address the problem of estimating the parameters of structured environments by means of continuous-variables quantum probes. Considering a very general time-local master equation describing the interaction of a thermal reservoir with a single quantum harmonic oscillator, we derive the ultimate bounds to the estimability of the cutoff frequency of Ohmic, sub-Ohmic and super-Ohmic environments. In particular, we determine interesting scaling laws for the quantum Fisher information in terms of the environment temperature, the parameters of the initial Gaussian state (squeezed thermal state) and interaction time. The study of the Fisher information for feasible measurement schemes, brings to a result of great relevance: a simple homodyne scheme allows to reach the best attainable precision in estimating the value of the reservoir cutoff frequency. Eventually, we analyze the optimization of this estimation protocol in different situations: classical coherent component in the probe state, effects of non-Markovianity and possible use of entangled probes.