In this talk, I will describe our experiments studying spin-dependent quantum transport, chemistry and interferometry in a Bose-Einstein condensate (BEC) of ultracold (87Rb) atoms subject to optically-generated “synthetic” spin-orbit coupling (SOC). We demonstrate spin-resolved atomic beam splitters and two-pathway interferometers based on tunable Landau-Zener transitions in the energy-momentum space (synthetic band structures generated by the SOC as well as Floquet-engineering) [1]. We also demonstrate a new approach of quantum control of (photo) chemical reactions (photoassociation of molecules from atoms) --- a “quantum chemistry interferometry” --- by preparing reactants in (spin) quantum superposition states and interfering multiple reaction pathways [2]. By performing a “quantum quench” in a SOC BEC, we induce head-on collisions between two spinor BECs and study spin transport and how it is affected by SOC, revealing rich phenomena arising from the interplay between quantum interference and many-body interactions [3]. Time permitting, I may discuss our recent realization of a (bosonic) topological state with band crossings protected by nonsymmorphic symmetry [4], by creating a “synthetic” cylinder with combined physical and synthetic dimensions and also a synthetic radial magnetic flux, where the BEC acquires an emergent crystalline order and exhibits quantum transport (Bloch oscillations) mimicking motion on a Mobius strip in energy-momentum space (band structure). Our experimental system can be a rich playground to study physics of interests to AMO physics, quantum chemistry, condensed matter physics, and even high energy physics.

Refs:
[1] A. Olson et al., “Tunable Landau-Zener transitions in a spin-orbit coupled Bose-Einstein condensate”, Phys. Rev. A. 90, 013616 (2014); “Stueckelberg interferometry using periodically driven spin-orbit-coupled Bose-Einstein condensates”, Phys. Rev. A. 95, 043623 (2017)
[2] D. Blasing et al., “Observation of Quantum Interference and Coherent Control in a Photo-Chemical Reaction”, Phys. Rev. Lett. 121, 073202 (2018)
[3] C. Li et al., “Spin Current Generation and Relaxation in a Quenched Spin-Orbit Coupled Bose-Einstein Condensate”, Nature Communications 10, 375 (2019)
[4] C. Li et al., “A Bose-Einstein Condensate on a Synthetic Hall Cylinder”, arXiv: 1809.02122