Past Events

Abstract

Roughly a decade after the birth of quantum mechanics, E. Wigner pointed out, in Ann. Math. 40, 149 (1939), a fundamental principle of quantum mechanics, i.e., symmetry groups are projectively represented, and applied this principle to study the Poincare group. While the Poincare group is the unique spacetime group of relativistic particles, its counterpart in condensed matter consists of various space groups for crystals and the time reversal.  In this sense, the projective representation of condensed-matter spacetime groups is much richer, and is of fundamental importance. However, the projective representation of crystal symmetry was not systematically investigated until recently. In this talk, I will systematically introduce our recent works and our research plans on this subject. Moreover, I will show some connections of projective crystal symmetry with topological phases of matter, and present some novel consequences. 

References:
1. Classification of time-reversal-invariant crystals with gauge structures, Z. Y. Chen, Z. Zhang, S. A. Yang, Y. X. Zhao*, Nat. Comm. accepted (2023)
2. Brillouin Klein bottle from artificial gauge fields, Z. Y. Chen, S. A. Yang, Y. X. Zhao*, Nat. Comm. 13, 2215 (2022)
3. The gauge-field extended k.p method and novel topological phases, L. B. Shao^#, Q. Liu^#, R. Xiao, S. A. Yang, Y. X. Zhao*, Phys. Rev. Lett. 127, 076401 (2021)
4. Switching spinless and spinful topological phases with projective PT symmetry, Y. X. Zhao*, C. Chen, X. L. Sheng, S. A. Yang, Phys. Rev. Lett. 126, 196402 (2021)

Anyone interested is welcome to attend.