量子信息交叉中心学术报告025
Title:Symmetry and Correlation Aspects of Quantum Dynamics
Speaker:Prof. Congjun Wu，University of California, San Diego
Place: RM 101，Bulg. 2，Xixi Campus (西溪校区西二楼101室)
Date and time: 14:00，Aug 28th，2019 （8月28日下午14:00）
Abstract：Symmetry and correlation are fundamental aspects of condensed matter physics. A solid state textbook typically starts with crystalline symmetries as classified by space group, and proceeds with the Bloch theorem which sets up the framework of electron’s quantum behavior under crystalline symmetries. We have generalized these concepts to dynamic systems by proposing “dynamic crystal” and updating the Bloch theorem. A new structure of “space-time group” is constructed for describing dynamic symmetries, including the space-time intertwined symmetries of “time-screw-rotation” and “time-glide-reflection”. Dynamic crystal applies to a large class of systems including laser-driven solid state crystals, dynamic photonic crystals and optical lattices. On the other hand, the real frequency responses at high energies is a hardcore problem of strong correlation physics. Our new progress is to employ integrable methods to investigate spin dynamics arising from the Bethe string states, which are exotic many-body excitations of high energy magnon anti-bound states. In particular, the 3-string excitations, i.e., the 3-body anti-bound states, are identified for the first time by comparing the characteristic spectra lines in the electron-spin-resonance spectroscopy measurement on SrCo2V2O8 with the theory calculations.
References:
1. S. L. Xu and C. Wu, Phys. Rev. Lett. 120, 096401 (2018) .
2. W. Yang, J. D. Wu, S. L. Xu, Z. Wang, C. Wu, arXiv:1702.01854.
3. Z. Wang, J. Wu, W. Yang, A. K. Bera, D. Kamenskyi, A.T.M. N. Islam, S. Xu, J. M. Law, B. Lake, C. Wu, A. Loidl, Nature 554, 219 (2018).
Biography：Congjun Wu received his Ph.D. in physics from Stanford University in 2005, and did his post-doctoral research at the Kavli Institute for Theoretical Physics, University of California, Santa Barbara, from 2005 to 2007. He became an Assistant Professor in the Department of Physics at the University of California, San Diego (UCSD) in 2007, an Associate Professor at UCSD in 2011, and a Professor at UCSD in 2017. His research interests include quantum dynamics, quan-tum magnetism, superconductivity, orbital physics, and topological states in condensed-matter and cold-atom systems. He was awarded an APS fellowship nominated by the Division of Con-densed Matter Physics in 2018, an AFOSR Young Investigator Award in 2011, a Sloan Research Fellowship in 2008, and an Outstanding Young Researcher Award from Overseas Chinese Phys-ics Society in 2008.