Probing entanglement in a many-body–localized system

• Published in: Science (American Association for the Advancement of Science) Vol. 364; no. 6437; pp. 256 - 260
• Main Authors: Lukin, Alexander, Rispoli, Matthew, Schittko, Robert, Tai, M. Eric, Kaufman, Adam M., Choi, Soonwon, Khemani, Vedika, Léonard, Julian, Greiner, Markus
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 19.04.2019; The American Association for the Advancement of Science
• Subjects: Chain entanglement; Chains; Computer memory; Correlation analysis; Entropy; Evolution; Localization; Many body problem; Physicists; Position (location); Quantum entanglement; Quantum theory; RESEARCH ARTICLE; Rubidium; Scientific Concepts; Subsystems; Thermalization (energy absorption); Thermodynamics; Variation
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.aau0818

An interacting quantum system that is subject to disorder may cease to thermalize owing to localization of its constituents, thereby marking the breakdown of thermodynamics. The key to understanding this phenomenon lies in the system’s entanglement, which is experimentally challenging to measure. 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 nonlocal correlations, whose evolution is consistent with a logarithmic growth of entanglement entropy, the hallmark of many-body localization. Our work experimentally establishes many-body localization as a qualitatively distinct phenomenon from localization in noninteracting, disordered systems.