强磁场科学论坛邀请了马克斯·普朗克复杂系统物理研究所吴建达博士访问中心并作学术报告，欢迎大家参加，请感兴趣的老师同学相互转告！

　　时间：3月22日（周四）15:00

　　地点：磁体装备厅203会议室

　　报告题目：String excitations in the anti-ferromagnetic Heisenberg-Ising XXZ chain — physics beyond universality

　　报告摘要：

　　Although the low energy fractional excitations of one dimensional integrable models are often well-understood, exploring quantum dynamics in these systems remains challenging in the gapless regime, especially at intermediate and high energies. Based on the algebraic Bethe ansatz formalism, we study spin dynamics in the anti-ferromagnetic spin-1/2 XXZ chain with the Ising anisotropy via the form-factor formulae. Various excitations at different energy scales are identified crucial to the dynamic spin structure factors under the guidance of sum rules. At small magnetic polarization, gapless excitations of psinons and antipsinons dominate the low energy spin dynamics. In contrast, spin dynamics at intermediate and high energies is characterized by the two- and three-string states. The dynamic spectra of the identified dominant excitations evolve with clear energy separations when tuning the magnetic field, conveying a simple and straightforward way to clearly identify the novel string excitations in proper condensed matter systems. Our predictions have been experimentally confirmed on the quasi-one-dimensional material SrCo2V2O8, where the details of the experimental observations will also be discussed.

　　报告人简介：

　　吴建达博士于2014年获得美国Rice大学的博士学位，之后在Rice大学、加州大学San Diego分校从事研究工作，2017年9月开始在马克斯·普朗克复杂系统物理研究所工作。吴建达博士的主要研究方向有：Quantum phase transition；Quantum critical dynamics and thermodynamics；Bethe ansatz and dynamics in integrable systems；Entanglement and topology in many body systems；Time-dependent many body systems and quantum adiabatic evolution，并在PRL，Nature等国际学术期刊上发表多篇学术论文。