Transport and disorder-induced localization of ultracold Fermi gases

We experimentally study localization and dynamics of ultracold fermions in speckle and optical lattice potentials to explore Anderson localization, many-body localization, and relaxation dynamics in strongly correlated systems. Anderson localization is probed by releasing non-interacting, spin-polarized gases into three dimensional, anisotropic disordered potentials produced from optical speckle. A fraction of the atoms are localized by the disorder, and a mobility edge is found separating localized from extended states. The length scale of the speckle is varied, and the localized state is found to scale linearly with the geometric mean of the speckle autocorrelation length. We realize the Fermi Hubbard model by loading atoms in a cubic optical lattice. Non-equilibrium momentum distributions are created via Raman transitions, and the excitation relaxation rate is measured in the lattice. Transport experiments were performed in a disordered optical lattice to explore the disordered Hubbard model. These experiments reveal localization in the presence of strong interactions and an interaction driven metal-to-insulator transition. The localized state is found to be insensitive to a doubling in the temperature of the gas and is consistent with predictions of many-body localization.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• McGehee, William R

Contributors dc:contributor

• DeMarco, Brian L.
• Mason, Nadya
• Gadway, Bryce
• Clark, Bryan

• Anderson Localization
• Many-Body Localization
• Optical Speckle
• Optical Lattice
• Ultracold Atoms
• Disordered Transport
• Strongly-Interacting Materials
• Hubbard Model
• Fermi-Hubbard Model
• Fermi Gas

Statement dc:rights

• Copyright 2015 William Russell McGehee

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/88039

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/88039