报告地点：行健楼学术活动室526

邀请人：朱建栋教授

Abstract: In this talk, we discuss quantum linear systems from a control-theoretic point of view. We present the Kalman canonical form for quantum linear systems. As an application, we show how it can be used to study decoherence-free (DF) modes, quantum non-demolition (QND) variables, and back-action evading (BAE) measurements in quantum information science. The proposed theory will be demonstrated by several experiments from quantum optics and opto-mechanical systems, including:

1. Optomechanical dark mode, Dong et al., Science, 338:609--1613, 2012.

2. Quantum backaction evading measurement of collective mechanical modes, Ockeloen-Korppi, et al.,Physical Review Letters, 117:140401,2016.

3. Light-mediated strong coupling between a mechanical oscillator and atomic spins 1 meter apart, Karg, et al.,Science 369:174–179,2020.

4. Quantum mechanics–free subsystem with mechanical oscillators, de Lepinay, et al., Science 372:625–629, 2021.

Then, we study how a quantum linear system processes continuous-mode multi-channel multi-photon states. If the quantum system is passive, then the higher-order singular value decomposition (HOSVD) precisely characterizes the input-output photon conversion.

Bio: Guofeng Zhang received his B.Sc. degree and M.Sc. degree from Northeastern University, Shenyang, China, in 1998 and 2000 respectively. He received a Ph.D. degree in Applied Mathematics from the University of Alberta, Edmonton, Canada, in 2005. During 2005–2006, he was a Postdoc Fellow at the University of Windsor, Windsor, Canada. He joined the School of Electronic Engineering of the University of Electronic Science and Technology of China, Chengdu, China, in 2007. From April 2010 to December 2011 he was a Research Fellow at the Australian National University. He is currently an Associate Professor in the Department of Applied Mathematics at the Hong Kong polytechnic University. His research interests include quantum information and control, sampled-data control and nonlinear dynamics.