Rostock 2019 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 4: Quantum Gases (Bosons) I

Q 4.1: Group Report

Monday, March 11, 2019, 10:30–11:00, S HS 037 Informatik

Quantum correlations across the many-body localization transition — •Julian Léonard, Matthew Rispoli, Alexander Lukin, Robert Schittko, Sooshin Kim, Joyce Kwan, and Markus Greiner — Harvard University, Cambridge, MA, USA

An interacting quantum system that is subject to disorder may cease to thermalize due to localization of its constituents, thereby marking the breakdown of thermodynamics. We realize such a many-body-localized system in a disordered Bose-Hubbard chain and characterize its entanglement properties through particle fluctuations and correlations.

We observe that the particles become localized, suppressing transport and preventing the thermalization of subsystems. Notably, we measure the development of non-local correlations, whose evolution is consistent with a logarithmic growth of entanglement entropy - the hallmark of many-body localization. These results experimentally establish many-body localization as a qualitatively distinct phenomenon from localization in non-interacting, disordered systems.

Furthermore, we characterize the entanglement properties at the many-body localization transition by their quantum correlations. In the quantum critical regime, we observe anomalous diffusive transport and the emergence of strong correlations in the system. The correlations form by a sparse network that spans the entire system and extends to high orders, signaling the presence of multi-particle entanglement. Our results describe the structure of the quantum critical many-body state, and they provide an essential step to understanding criticality and universality in non-equilibrium systems.