Localization in spin chains with facilitation constraints and disordered interactions

Ostmann, Maike; Marcuzzi, Matteo; Garrahan, Juan P; Lesanovsky, Igor

Abstract

Quantum many-body systems with kinetic constraints exhibit intriguing relaxation dynamics. Recent experimental progress in the field of cold atomic gases offers a handle for probing collective behavior of such systems, in particular for understanding the interplay between constraints and disorder. Here we explore a spin chain with facilitation constraints-a feature which is often used to model classical glass formers-together with disorder that originates from spin-spin interactions. The specific model we study, which is realized in a natural fashion in Rydberg quantum simulators, maps onto an XX-chain with non-local disorder. Our study shows that the combination of constraints and seemingly unconventional disorder may lead to interesting non-equilibrium behaviour in experimentally relevant setups. Introduction-Localization phenomena in many-body quantum systems are currently under extensive investigation. Initially, localization was discussed by Anderson [1] for non-interacting quantum particles in disordered potential landscapes. Since then the focus has increasingly shifted to the many-body domain, partially fueled by the development of refined techniques to experimentally engineer and probe many-body systems with cold atoms [2]. By now, evidence has been found that in isolated , one-dimensional, interacting systems the presence of disorder induces a phase transition from a thermal to a many-body localized one where ergodicity breaks down [3-20]; for reviews see [21-23]. Experiments [20, 24-26] have confirmed theoretical predictions, and signatures of MBL have also been identified in two-dimensional systems [27]. Aspects of MBL are also present in systems with weak periodic driving [28], in systems with disordered interactions [29, 30] as well as in systems coupled to an environment [31-36]. A second mechanism for interesting quantum relaxation is via constraints in the dynamics. In analogy with what occurs in models of classical glasses [37], quantum systems with kinetic constraints can display very slow and complex relaxation [38-40] and can be used to probe the emergence of MBL-like physics in the absence of disorder [41-51]. Hamiltonians with kinetic constraints can display particular many-body eigenstates that generalize the concept of quantum scars to interacting systems [52-55]. Constraints can further impose restrictions on the quantum dynamics either by removing states from the Hilbert space and/or by cutting off transition pathways between states. Supplemented by the presence of disorder , it is expected that constrained systems become very prone to localisation [56]. Here we are interested in understanding localization in disordered spin chains in the presence of facilitation kinetic constraints. Such a scenario was recently realized experimentally [57] within an optical lattice quantum simulator consisting of individually trapped Rydberg atoms [58-61]. Here atoms are excited in a way that

Citation

Ostmann, M., Marcuzzi, M., Garrahan, J. P., & Lesanovsky, I. (2019). Localization in spin chains with facilitation constraints and disordered interactions. Physical Review A, 99(6), 1-7. https://doi.org/10.1103/PhysRevA.99.060101

• Journal Article Type: Article
• Acceptance Date: May 14, 2019
• Online Publication Date: Jun 6, 2019
• Publication Date: Jun 6, 2019
• Deposit Date: Jun 18, 2019
• Publicly Available Date: Jun 19, 2019
• Journal: Physical Review A
• Print ISSN: 2469-9926
• Electronic ISSN: 2469-9934
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 99
• Issue: 6
• Article Number: 060101(R)
• Pages: 1-7
• DOI: https://doi.org/10.1103/PhysRevA.99.060101
• Public URL: https://nottingham-repository.worktribe.com/output/2059764
• Publisher URL: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.99.060101
• Contract Date: Jun 18, 2019