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講座題目：A tale from the transverse-field Ising chain to quantum E8 integrable model

報  告  人：吳建達 教授 上海交通大學 李政道研究所

時       間：11月18號（星期三）16：00

地 點：理工樓801會議室

Exotic thermodynamics and excitations can emerge in the vicinity of a quantum phase transition. In the talk, I will first detailedly discuss the very unique quantum criticality for the Grüneisen ratio in the transverse field Ising chain (TFIC). The unique quantum criticality of the Grüneisen ratio then serves as a smoking gun to identify the underlying TFIC universality observed in quasi-1D antiferromagnetic materials BaCo2V2O8 and SrCo2V2O8, which clearly establishes the realization of the TFIC universality for the first time. Furthermore, when the quantum critical point of the TFIC is perturbed by a longitudinal magnetic field, it was predicted that its massive excitations are precisely described by the exceptional E8 Lie algebra. Here we show an unambiguous experimental realization of the massive E8 phase in the material BaCo2V2O8, via nuclear magnetic resonance and inelastic neutron scattering measurements, and detailed theoretical analysis. The large separation between the masked 1D and 3D quantum critical points of the system allows us to identify, for the first time, the full 8 single-particle E8 excitations as well as various multi-particle states in the spin excitation spectrum. Our results open new experimental route for exploring the dynamics of quantum integrable systems and physics beyond integrability, and thus bridge key physics in condensed matter and statistical field theory.

吳建達教授，在中國科學技術大學取得學士和碩士學位，在萊斯大學取得博士學位；隨后在圣地亞哥加州大學物理系從事博士后工作；任麥克斯普朗克物理復合系統研究所客座科學家；從2018年至今以李政道學者榮譽加入上海交通大學李政道研究所，同時擔任物理與天文學院長聘教軌副教授。目前的研究興趣包括：量子相變、量子臨界動力學和熱力學、可積系統中的Bethe ansatz和動力學、多體系統中的糾纏和拓撲等物理問題。