Time:  14:00  (UTC/GMT+8:00, Beijing/Shanghai), Dec. 9 (Thur.) , 2021

Zoom URL: https://us06web.zoom.us/j/83807310012?pwd=RE54bWVTUCswMklBU2pVMStxd2txQT09

Meeting ID: 838 0731 0012

Password: 123456

Speaker: Xiao-Peng Li (Fudan)

Abstract:

The spin and orbital degrees of freedom both play important roles in our understanding of electron correlations in molecules and quantum materials. Quantum simulations of spins in cold atom systems have led to rich quantum magnetism such as antiferromagnetic states and spin liquids. With orbitals, exotic superfluids with striped and chiral orders have been achieved in the last decade. Here, we present our study on how multi-component bosonic quantum gases condense in high-orbital bands. We find a novel mechanism of spontaneous spin-orbital coupling that originates from interaction driven spin-momentum locking [1] or spin-angular-momentum locking [2], and establish a robust symmetry principle underlying this mechanism. The spin-momentum locking, and the spin-angular-momentum, are attributed to translation and rotation symmetries, respectively. Our theory is further applied to a chiral molecular system, where a quantum transport phenomenon of chiral induced spin selectivity was discovered almost two decades but lacks a theoretical explanation. Our theory provides an anomalous spin-orbital coupling that is sufficient for accommodating chiral induced spin selectivity even at room temperature [3].

Ref.1: Xiaopeng Li, Stefan Natu, Arun Paramekanti, S. Das Sarma, “Chiral magnetism and spontaneous spin Hall effect of interacting Bose superfluids”, Nature Communications 5: 5174 (2014)

Ref.2: Yongqiang Li, Jianmin Yuan, Andreas Hemmerich, Xiaopeng Li, “Rotation symmetry enforced coupling of spin and angular-momentum for p-orbital bosons”, Phys. Rev. Lett 121, 093401 (2018)

Ref.3: Xiaopeng Li, Jue Nan, Xiangcheng Pan, “Chiral induced spin selectivity as a spontaneous intertwined order”, Phys. Rev. Lett 125, 263002 (2020)

About the Speaker:

Xiaopeng Li is professor of physics in the Physics Department of Fudan University, China, jointly employed by Shanghai Qi Zhi Institute. He is active in quantum information science and condensed-matter theories, with his primary research interests in exploiting the quantum computation power of various quantum simulation platforms. He received his Ph.D. in physics from the University of Pittsburgh in 2013 and joined Fudan University as a faculty member in 2016 after three years at the University of Maryland, supported by a Joint Quantum Institute theoretical postdoctoral fellowship. He has been a full professor since 2019.