SAMOP 2023 – wissenschaftliches Programm

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SYAD: Symposium SAMOP Dissertation Prize 2023

SYAD 1: SAMOP Dissertation Prize Symposium (SYAD)

SYAD 1.3: Hauptvortrag

Montag, 6. März 2023, 15:30–16:00, E415

Particle Delocalization in Many-Body Localized Phases — •Maximilian Kiefer-Emmanouilidis — Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany — Deutsches Forschungszentrum für Künstliche Intelligenz, Kaiserslautern, Germany — University of Manitoba, Winnipeg, Canada

Can a generic isolated quantum many-body system avoid thermalization? Textbook thermodynamics say no, at least for any generic interacting system. In 2006 Basko et al. argued to the contrary and described the phenomenon known today as many-body localization (MBL), where in highly disordered materials interacting electrons may localize in space, thus withstanding thermalization. In this talk I present evidence gathered during my dissertation which fundamentally questions the current picture of the MBL phase. I show that even in the paradigmatic model of MBL, where the von Neumann entanglement entropy grows S ∼ lnt particles can spread subdiffusively. In my dissertation I studied the contribution to a systems entanglement entropy which stems from particle-number fluctuations. This quantity known as the number entropy S_N describes the entanglement generated by particles moving between partitioning cuts and is easily accessible in setups of ultracold atoms utilizing a quantum gas microscope. In a system that exhibits MBL, particles should travel only short distances, and thus S_N should be bounded after a quench. I have shown numerically that the number entropy grows proportional to the entanglement entropy, S_N ∼ ln S ∼ ln ln t, and is therefore unbounded if S is unbounded. This questions the existence of the MBL phase.