【大学频道】北京大学量子材料科学中心呈献 | 东京大学龚宗平博士

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题   目：Topological phases of non-Hermitian systems报告人：龚宗平单   位：University of Tokyo时   间：2019-06-10地   点：北京大学

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报告摘要

Recent experimental advances in controlling dissipation have brought about unprecedented flexibility in engineering nonHermitian Hamiltonians in open classical and quantum systems. A particular interest centers on the topological properties of non-Hermitian systems. However, no systematic understanding in analogy with Hermitian topological insulators and superconductors has been achieved. In this seminar, we introduce a coherent framework for classifying free-fermion-like non-Hermitian topological phases, within which we work out the periodic table for all the nonHermitian systems with Altland-Zirnbauer symmetries in all dimensions. In particular, we find that a one-dimensional nonHermitian lattice can be topologically nontrivial even without symmetry protection (class A), reminiscent of the quantum Hall insulator in Hermitian systems. The primary example is the Hatano-Nelson model, in which the Anderson transition can be understood from a topological viewpoint. We will also discuss a remarkable observation that the timereversal and particle-hole symmetries are unified, as well as some examples in other symmetry classes in zero and one dimensions.

个人简介

Zongping Gong graduated from Peking University with a B.S. degree in 2015. He is now a fourth-year PhD student at the University of Tokyo, supervised by Prof. Masahito Ueda. He is working on various topics on nonequilibrium physics, including quantum and stochastic thermodynamics, nonequilibrium phases of matter, and dynamical topological phenomena.

—— ——往期精彩回顾—— ——● 北京大学量子材料科学中心呈献 | Yonglong Xie of Princeton University: Visualizing topological and correlated phases with a scanning tunneling microscope● 北京大学量子材料科学中心呈献 | 犹他大学黄华卿研究员：Theoretically Tracing Topological States: from crystals to quasicrystals and to noncrystalline systems● 北京大学量子材料科学中心呈献 | Hengyun Zhou of Harvard University：Surpassing the Interaction Limit to Quantum Metrology with Fault-Tolerant Control● 北京大学量子材料科学中心呈献 | Gang Cao：Control of Quantum States in 4d/5d Transition Metal Oxides● 北京大学量子材料科学中心呈献 | Patrick Rinke：The Artist: Artificial Intelligence for Spectroscopy
● 北京大学量子材料科学中心呈献 | 佛罗里达大学张晓光教授：Multi-phonon processes in solids from first-principles● 北京大学量子材料科学中心呈献 | 中国科学技术大学翟晓芳研究员：Complex oxide thin films and heterostructures for novel physics and applications● 北京大学量子材料科学中心呈献 | Michael S. Fuhrer：Topological materials for low-energy electronics● 北京大学量子材料科学中心呈献 | 李卫东：Geometric property of Quantum States and its application on Entanglement Criteria● 北京大学量子材料科学中心呈献 | 吴留锁：Neutron Scattering and Spinon Excitations in Perovskite Quantum Magnet YbAIO₃

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