Group seminar via Zoom: Non-Hermiticity in spin-orbit coupled BECs

Junheng Tao, University of Maryland, USA
Group seminar via Zoom
Thursday, February 8, 09:00 am (MEZ)

Abstract: In 1996 Hatano and Nelson proposed a non-Hermitian lattice model containing an imaginary Peierls phase [Phys. Rev. Lett. 77, 570--573 (1996)], and subsequent analyses revealed it that is an instance of a new class of topological systems. We experimentally realize a continuum analog to this model containing an imaginary gauge potential in a homogeneous spin-orbit coupled Bose-Einstein condensate (BEC). The base spin-orbit coupled Hamiltonian is made non-Hermitian by adding tunable spin-dependent loss by microwave coupling to a lossy intermediate state. We find that the Heisenberg equations of motion for position and momentum with an imaginary gauge potential depend explicitly on the system's phase-space distribution. Our experiment first revealed collective nonreciprocal transport in real space, where the acceleration is a decreasing function of BECs spatial extent in agreement with non-Hermitian Gross-Pitaevskii equation simulations. Lastly, we observed the non-Hermitian skin effect by localizing an initial state at the trap boundary, and verifying that it was stationary. In addition, I will discuss the promise of utilization of non-Hermicity for fun quantum simulations.