Group Seminar at MPQ: Modifying spin diffusion in a nondegenerate ultracold gas

Sean Graham, Simon Fraser University

July 15, 2019

Sean Graham, Simon Fraser University
MPQ Garching, Hans-Kopfermann-Str. 1,
Herbert-Walther lecture hall
Monday 07/15, 9:15am

Modifying spin diffusion in a nondegenerate ultracold gas

Abstract: Diffusion plays a major role in our daily lives, whether it’s with the diffusion of heat to keep our computers cool or the diffusion of gases in the Earth’s atmosphere that affects the local weather. Classical diffusion describes these two examples fairly well; however, the diffusion of quantum properties is not as well understood, especially at low temperatures or high densities. Learning how to control spin diffusion in semiconductors could lead to new ultra-low-power devices that work similarly to modern electronics, but operate with spin instead of charge. Rather than study spin diffusion directly in semiconductors, we use ultracold atoms as they offer a tunable experimental playground to study the diffusion of spin at various temperatures and densities. Spin diffusion is explored in our quasi-1D ultracold gas by initializing different spin inhomogeneities and imaging snapshots of the time evolution for each spin component. Our group has shown that spin diffusion can be significantly modified by applying a small local Larmor precession to a two-domain spin profile. I will present results highlighting the effects of coherence and local Larmor precession on spin diffusion within the nondegenerate regime. In addition, we can infer spin diffusion guidelines that could be relevant for manipulating spin diffusion in other nonequilibrium systems.

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