CMP Seminars：Symmetry Fractionalization and Anomaly Test (Xie Chen, California Institute of Technology , July 21)

CMP Seminars

Title:  Forces that drive the formation of self-assembled nanostructures

Speaker: Xie Chen, California Institute of Technology

Location: Room 1206, Physics Building

Time: 10:00-11:00, Tue, July 21, 2015

Abstract:

In 2D topological phases with symmetry, the fractional excitations in the system can transform under symmetry in a fractional way, e.g. by carrying fractional symmetry charges. With different types of topological order and different symmetries, what symmetry fractionalization (SF) patterns are possible in general? This question becomes particularly interesting with recent experimental progress towards realizing spin liquids and we try to answer this question in this talk. In particular, we point out that some seemingly consistent SF patterns are actually anomalous, i.e. they cannot be realized in purely 2D systems. To exclude these cases, we discuss two anomaly detection methods: the flux fusion method, which is physically intuitive but applies only to special cases, and the gauging obstruction method, which is mathematically complete and straight-forward to apply. We give specific examples of anomalous SF patterns to be detected by these methods and discuss the interesting possibility of realizing them on the surface of 3D systems.

Biography:

Professor Xie Chen received her Bachelor of Science’s degree from Tsinghua University in physics in 2006. She was a graduate student at Massachusetts Institute of Technology, working with Professors Isaac Chuang and Xiao-Gang Wen. She received her Ph.D. degree in 2012 and went to University of California at Berkeley as a Miller fellow. Professor Chen joined California Institute of Technology in 2014 as a tenure track assistant professor. Her work focuses on strongly interacting topological phases, taking a quantum information perspective, especially the entanglement perspective, in studying such systems.