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理学大师论坛——林海青院士:激发、自旋-电荷分离与量子相变

编辑: 时间:2021年03月30日 访问次数:0

题目: 激发、自旋-电荷分离与量子相变

报告人:林海青院士    北京计算科学研究中心

时间:42日(周五)15:30-16:30

地点:玉泉校区 教十二-201

 

摘要

Quasi-particles play important role in condensed matter physics and result in many emergent novel phenomena. In this talk, we discuss collective excitations in one-dimension as exemplified by antiferromagnetic Heisenberg model and δ-function interacting Fermi gas (Yang-Gaudin model). Using the thermodynamic Bethe ansatz (TBA) formalism, we analytically derive universal properties of the models with arbitrary interaction strength, and present a rigorous understanding of spin-charge separation, a unique feature predicted by the Tomonaga-Luttinger liquid (TLL) theory.  Spinon, as an elementary spin excitation, is responsible for the TLL. We show that a dimensionless quantity, the Wilson ratio (RW), elegantly characterizes quantum liquid phase diagram. For the TLL phase, RW = 4Ks remains almost temperature independent, where Ks is the Luttinger parameter. WR can be used to identify quantum phase transitions for a wide variety of materials. Based on the exact low-lying excitation spectra, we further evaluate the spin and charge dynamical structure factors (DSFs). The peaks of the DSFs exhibit distinguishable propagating velocities of spin and charge as functions of interaction strength, which can be observed by Bragg spectroscopy with ultracold atoms.

 Acknowledgements: NSAF U1930402 and NSFC 11734002, as well as computational resources from the Beijing Computational Science Research Center

 Collaborators:

Guan XW Group: Feng He, Yu-Zhu Jiang, Yi-Cong Yu, Yang-Yang Chen,

Rich Univ./US: Randall G. Hulet, Han Pu

Univ. of Warwick/UK: Rudolf A. Romer

Bethe Ansatz Group: X.-G. Yin A. Foerster, M. T. Batchelor, C.-H. Lee

 

简历

Lin, Haiqing

1981年于中国科学技术大学获得学士学位。1980年参加CUSPEA项目。

1983年于美国Iowa州立大学获得理学硕士学位。

1987年于美国加州大学San Diego分校物理系获得物理学博士学位。

1987年至1989年任美国Brookhaven国家实验室副研究员(Research Associate)。

1989年至1991年任美国Los Alamos国家实验室副研究员(Research Associate)。

199110月至19957月任美国University of Illinois at Urbana-Champaign物理系Research Assistant Professor

19958月至20129月任香港中文大学物理系副教授、教授。

20098月至今任中国工程物理研究院、北京计算科学研究教授。

2019年当选中国科学院院士。

欢迎老师和同学参加!