【报告题目】 Resolving spinon continuum by 2D coherent spectroscopy
【报 告 人】 万源 研究员
中科院物理研究所
【时 间】 2019-09-25 4:00 pm (Wedensday)
【地 点】 北园106报告厅
【报告摘要】
Fractionalization is a phenomenon in which the elementary excitations of a many-body system are made by breaking apart the constituent degrees of freedom. For instance, in the quantum Ising chain, the elementary excitation is a domain wall, also known as a spinon, which can be thought of as half of a spin. While local external perturbations may excite phonons and magnons from the vacuum one at a time, the spinons must be created in pairs. As a result, in dynamic probes including neutron scattering and electron spin resonance, the spinons appear as a broad continuum of signal rather than a sharp resonance. The spinon continuum hides the intrinsic spectral properties of spinons such as their line width and line shape, thereby concealing the spinons’ dynamical properties. In this talk, I will show that two-dimensional coherent spectroscopy (2DCS) is an ideal tool to analyze the dynamical properties of fractional excitations. Using quantum Ising chain as a prototypical example, I show theoretically that the 2DCS can resolve the spinon continuum and directly reveal the lifetime of a pair of spinons. This is possible thanks to the spinon echo process, which is an incarnation of the photon echo in the context of spinon dynamics.
【报告人简介】
Yuan Wan obtained his Ph.D. in physics from the Johns Hopkins University in 2014. He was a postdoctoral researcher in the Perimeter Institute for Theoretical Physics from 2014 to 2017, and a postdoctoral research assistant in the Rudolf Peierls Centre for Theoretical Physics in the University of Oxford from 2017 to 2018. He joined the Institute of Physics, Chinese Academy of Sciences as an associate researcher in 2018 and has been there since then. With a broad interest in theoretical physics, his current research focuses on the interplay between geometrical frustration and many-body dynamics.