报告题目：Non-Hermitian spin-orbit-coupled quantum gases

报告人：Gyu-Boong Jo     Department of Physics, HKUST

报告时间：2021年11月16日（周二） 9：00

报告地点：理六栋302        邀请人：张善超

报告内容：

        While spin-orbit coupling (SOC), an essential mechanism underlying quantum phenomena from the spin Hall effect to topological insulators, has been widely studied in well-isolated Hermitian systems, much less is known when the dissipation plays a major role in spin-orbit-coupled quantum systems. I will report the realization of the non-Hermitian spin-orbit-coupled quantum gases and observation of a parity-time (PT ) symmetry- breaking transition as a result of the competition between SOC and dissipation. In our experiment, tunable dissipation, introduced by state-selective atom loss, enables the energy gap, opened by SOC, to be engineered and closed at the critical dissipation value, the so-called exceptional point (EP) . The realized EP of the non-Hermitian band structure exhibits chiral response when the quantum state changes near the EP. This topological feature enables us to tune SOC and dissipation dynamically in the parameter space, and observe the state evolution is direction- dependent near the EP, revealing chiral spin transfer between different quantum states when the quantum state encircles the EP. This topological control of quantum state for non-Hermitian fermions provides new methods of quantum control, and also sets the stage for exploring non-Hermitian topological states with SOC.

专家简介：

        Prof. Gyu-Boong Jo is currently Hari Harilela Associate Professor in the Department of Physics at The Hong Kong University of Science and Technology (HKUST), and leads the Laboratory for Ultracold Quantum Gases. He came to HKUST following his studies at the Massachusetts Institute of Technology (PhD 2010) where he was awarded the Samsung graduate fellowship and postdoctoral work at the University of California at Berkeley (2010-13). He obtained the Bachelor’s degree in Physics and Mathematics from the Seoul National University in 2003. He has received multiple awards including the AKPA Outstanding Young Researcher Award (OYRA) (2013), the Early Career Award from the Research Grant Council of Hong Kong (2014), the Croucher Innovation award (2016), the School of Science Research Award at HKUST (2019) and the UROP faculty award (2021).