题目：From local thermometry to general quantum multi-parameter global sensing

报告人：Victor Montenegro（中国电子科技大学）

时间：2021年7月20日14:30-16:00

地点：理工楼1226

邀请人：安钧鸿教授

报告摘要

Measuring the effective temperature of the oscillator is perhaps one of the most relevant steps in the characterization of quantum optomechanical systems. Conventionally, the cavity is strongly driven, and the overall system is well-described by a Gaussian preserving Hamiltonian. Here, we consider an undriven optomechanical system via non-Gaussian radiation-pressure interaction. We show that the optical probe gets a nonlinear phase, resulting from the non-Gaussian interaction, and undergoes an incoherent phase diffusion process. We propose using a nonlinear Kerr medium before a homodyne detector that enhances the precision to nearly saturate the ultimate quantum bound given by the quantum Fisher information. The above sensing procedure falls into local sensing, namely when the quantum sensor operates efficiently only when the unknown parameters vary within a very narrow region. In the second part of this talk, we present a systematic method for optimizing the sensor to operate with its best precision over any arbitrarily large interval, namely, global sensing. By exploiting quantum many-body probes, our protocol harnesses the criticality for significantly enhancing the precision of multi-parameter estimation, independent of the sensing intervals.

个人简介

Victor Montenegro received his B.Sc and M.Sc degree in Physics from Universidad Catolica de Chile. Then he received his PhD degree from University College London in 2015. Now he is a postdoctoral researcher of UESTC. He is working on quantum metrology with quantum optomechanics flavor and many-body physics.