报告题目：Topological Quantum Optics: witness of topological phase transition and point-gap topology

报告人：吕新友 教授 （华中科技大学）

报告时间：2023年10月17日（星期二） 上午 10：30

报告地点：致知楼3328

报告摘要：

In this presentation, I will firstly introduce the background of topological quantum optics and its applications. Secondly, I mainly introduce detecting topological phase transitions via an experimentally observable out-of-time-order correlation (OTOC). Specifically, the distinguishable OTOC dynamics appears in the topological trivial and nontrivial phases due to the topological locality, which is still valid even in the presence of disorder. Lastly, I will introduce our recent work regarding point-gap topology in quadratic bosonic system (QBS). We theoretically predict the squeezing-induced point-gap topology in a QBS. A $Z_{2}$ skin effect, extremely sensitive to local perturbations, is found in the Hermitian system for the first time, which surpasses the Bloch’s theorem. We also find a squeezing-induced unconventional topological phase where both the point-gap and line-gap topologies are nontrivial, and it is experimentally detectable. Our works is of fundamental interest in interest in enriching the topological physics by introducing the OTOC and quantum squeezing, and has potential applications for the engineering of new-type quantum detecting technology and symmetry-protected sensors based on skin effect.

报告人简介：

    吕新友，华中科技大学bwin必赢国际官网APP教授，博士生导师，国家自然科学基金“优秀青年基金”和湖北省“百人计划”获得者。主要从事腔量子电动力学（QED）和腔光力学等方面的理论研究。在Phys. Rev. Lett.、Nat. Commun.等杂志共发表论文70余篇，SCI总他引3800余次，10篇论文被引超过100次（6篇被引超过200次），H因子32。