报告人：Edbert J. Sie (Stanford University)
题目：Ultrafast Manipulation of Topological Phases in 2D Materials
报告摘要：Discovery of topological materials has sparked a worldwide interest to harness the topological properties of quantum matter, with important applications in dissipationless electronics and fault-tolerant quantum computing. One prime example is WTe2, which is a layered semimetal that crystallizes in a unique structure where the emergence of massless Weyl fermions in this system is sensitive to atomic-scale lattice distortions. In this talk, I will discuss the topological physics of WTe2, and show that its topological invariants are highly tunable by means of interlayer shear strain, as crystallographically measured using relativistic electron diffraction. We will discuss how ultrashort pulses of terahertz (THz) electromagnetic field can be used to drive the shear mode which in turn serves as an ultrafast, energy-efficient means to induce more robust, well-separated Weyl points or to annihilate all Weyl points of opposite chirality. These results define new methods for ultrafast manipulation of the topological properties in 2D materials that can operate at THz frequencies.
报告人简介：Dr. Edbert Sie is currently a GLAM Postdoctoral Fellow at Stanford University. He received his PhD in Physics at Massachusetts Institute of Technology. His research interests focus on engineering novel quantum phases of matter at non-equilibrium, with particular interests in 2D condensed matter systems. In combination with various ultrafast laser techniques, his research aims to innovate new ways of manipulating quantum materials at the atomic length scale and on femtosecond timescale.