Freiburg 2024 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 24: Poster II

Q 24.25: Poster

Dienstag, 12. März 2024, 17:00–19:00, KG I Foyer

Signatures of Anderson localization in a degenerate Fermi gas beyond exponential density distributions — •Sian Barbosa, Maximilian Kiefer-Emmanouilidis, Felix Lang, Jennifer Koch, and Artur Widera — Department of Physics and Research Center OPTIMAS, RPTU, Kaiserslautern, Germany

Disorder can fundamentally modify the transport properties of a system. A striking example is Anderson localization, suppressing transport due to destructive interference of propagation paths. Especially in inhomogeneous many-body systems, not all particles will localize for finite-strength disorder, and the system can become partially diffusive. Even for extended, i.e. non-localized states, exponential tails can develop after purely diffusive transport and falsely simulate localization, especially when the diffusion coefficient becomes energy dependent. I will present the results of our experimental investigation of a degenerate, spin-polarized Fermi gas released into a disorder potential formed by an optical speckle pattern. Using standard observables, such as diffusion exponent and coefficient, localized fraction, or localization length, we find that some show signatures for a transition to localization above a critical disorder strength, while others show a smooth crossover to a modified diffusion regime. In laterally displaced disorder, we spatially resolve different transport regimes simultaneously which allows us to extract the subdiffusion exponent expected for weak localization. Our work suggests alternative measures to the misleading concept of exponential tails.

Keywords: Anderson Localization; Anomalous Diffusion; Disordered Systems; Quantum Transport; Degenerate Fermi Gases