时间：2025年4月28日（周一）下午14:00-15:30

Time: 14:00-15:30 PM, Monday, April 28, 2025

地点： 西湖大学云谷校区E10-405

Venue: E10-405, Yungu Campus

主持人：西湖大学理学院讲席教授 吴从军

Host: Chair Professor Congjun Wu, School of Science, Westlake University

报告语言：英文

Language: English

吴建达博士，

上海交通大学教授/李政道研究所研究员

Dr. Jianda Wu, Professor/ Researcher Fellow at the School of Physics and Astronomy 

Shanghai Jiao Tong University/Tsung-Dao Lee Institute

主讲人简介/Biography:

Prof. Jianda Wu has long been committed to the research work in quantum phase transitions, quantum critical thermodynamics and dynamics, Bethe ansatz, and dynamics in quantum integrable systems. He obtained BS (2004) and MS (2007) degrees from University of Science and Technology of China, and got PhD (2014) from Rice University. From 2014-2017 he carried out postdoc research at University of California at San Diego, then (2017-2018) became a guest scientist at Max Planck Institute for the Physics of Complex Systems. Since 2018 he became a Tsung-Dao Lee Fellow at Tsung-Dao Lee Institute and a faculty member at School of Physics and Astronomy at Shanghai Jiao Tong University. Jianda has published more than 30 papers including Nature, Nature Physics, Nature Communications, and Phys. Rev. Lett. etc. So far, he has delivered more than 80 invited talks at international conferences/workshops, and institutes around the world.

摘要/Abstract:

When two transverse-field Ising chains (TFICs) with magnetic order are coupled, the original free excitations become confined, giving rise to meson-like bound states. In this work, we study such bound states systematically. The mesons are characterized by their fermion number parity and chain-exchanging properties, which lead to distinct sets of mesonic states. The meson masses are determined by solving the Bethe-Salpter equation. An interesting observation is the additional degeneracy in the chain-exchanging odd sectors. Beyond the two-particle approximation, we exploit the truncated free fermionic space approach to calculate the spectrum numerically. Corrections to the meson masses are obtained, and the degeneracy is further confirmed. The characterization and degeneracy can be connected to the situation when each chain is tuned to be quantum critical, where the system is described by the Ising_h² integrable model, a sine-Gordon theory with Z₂ orbifold. Here we establish a clear correspondence between the particles in the bosonized form and their fermionic counterparts. Near this point, the stability of these particles is analyzed using the form factor perturbation scheme, where four particles are always present. Additionally, we calculate the evolution of the dominant dynamical structure factor for local spin operators, providing further insight into the low-energy excitations and their role in the system’s behavior. The two-particle confinement framework as well as the parity classifications may inspire the study for other coupled bi-partite systems.

联系人/Contact：

理学院，朱老师，zhuyi48@westlake.edu.cn

Ms. Yi Zhu, School of Science, zhuyi48@westlake.edu.cn