【学术视频】“非厄米系统动力学演化及其拓扑性质”培训班 | 中山大学俞振华教授

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图 | 俞振华

题   目：Interaction effects on PT-symmetry breaking transition in atomic gases报告人：俞振华单   位：中山大学时   间：2019-12-15地   点：北京计算科学研究中心

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报告摘要

Non-Hermitian systems having parity-time (PT) symmetry can undergo a transition, spontaneously breaking the symmetry. Ultracold atomic gases provide an ideal platform to study interaction effects on the transition. We consider a model system of N bosons of two components confined in a tight trap. Radio frequency and laser fields are coupled to the bosons such that the single particle Non-Hermitian Hamiltonian, which has PT-symmetry, can be simulated in a passive way, namely in the physical system there is only incurred atom loss but no gain. We show that when interatomic interactions are tuned to maintain the symmetry, the PT-symmetry breaking transition is affected only by the SU(2) variant part of the interatomic interactions. We find that the transition point occurs at smaller dissipation as the strength of this interaction part or N increases; in the strong strength limit for this interaction part, the critical dissipation scales as the strength to the power of-(N-1). We also give signatures of the PT-symmetric and the symmetry breaking phases for the interacting bosons in experiment.

个人简介

俞振华，1999年9月-2003年7月在复旦大学物理系获得理学学士学位，2003年8月-2008年8月在美国伊利诺伊大学香槟分校物理系获得理学博士学位，2008年9月-2011年10月分别在丹麦玻尔研究所、美国俄亥俄州立大学物理系作博士后研究，期间曾在清华大学高等研究院做访问学者。2012年2月-2016年6月任清华大学高度研究院副研究员，2016年7月至今，任中山大学物理与天文学院教授、博士生导师。其主要从事冷原子物理的理论研究，并探索冷原子体系在精密测量等方面的应用。研究成果包括：1、给出了强相互作用费米气体关联性质的自洽计算，弥补了以往非自洽计算破坏守恒律的缺陷。2、建立了描述光频原子钟碰撞频移的赝自旋理论，解释了美国国家标准与技术研究院叶军实验组的观察结果，纠正了以往普遍认为费米原子钟不会有碰撞频移的错误观念。3、建立了描述谐振腔中基于原子密度关联等超辐射理论。4、揭示了三体“super Efimov”效应量子力学的基本理解。5、建立了p波共振气体的接触关联及其动力学理论。

会议简介

“非厄米系统动力学演化及其拓扑性质”培训班
The International Workshop on Frontiers in Quantum Physics and Quantum Information is a series workshop for theoretical and experimental quantum information research. This year, we focus on the topic “topology and dynamics in non-Hermitian systems”. Non-Hermitian Hamiltonians were not taken seriously in the past since they were assumed to be unphysical. With the advent of parity-time reversal symmetric systems possessing real eigenvalues and conserved probability, and with numerous experimental demonstrations, such Hamiltonians are now studied routinely as many novel features in non-Hermitian systems may or may not have any analogue in the Hermitian counterparts. Study of topological phases in non-Hermitian systems is one of the fastest growing and hot research topics. Some of the models have no direct analogy with the Hermitian counterparts and predict exotic topological phases which remained elusive in Hermitian systems but can be rather easily obtained in non-Hermitian systems. The scientific objects of the workshop are to gather widely recognized experts in the field to present and discuss groundbreaking work.
主办方：北京计算科学研究中心

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