Engineering random spin models with atoms in a high-finesse cavity

Year: 2023

Authors: Sauerwein N., Orsi F., Uhrich P., Bandyopadhyay S., Mattiotti F., Cantat-Moltrecht T., Pupillo G., Hauke P., Brantut JP.

Autors Affiliation: Ecole Polytech Fed Lausanne EPFL, Inst Phys, Lausanne, Switzerland; Ecole Polytech Fed Lausanne EPFL, Ctr Quantum Sci & Engn, Lausanne, Switzerland; Univ Trento, Pitaevskii BEC Ctr, CNR INO, Trento, Italy; Univ Trento, Dipartimento Fis, Trento, Italy; INFN TIFPA, Trento Inst Fundamental Phys & Applicat, Trento, Italy; Univ Strasbourg, Strasbourg, France; CNRS, CESQ, Strasbourg, France; ISIS UMR 7006, aQCess, Strasbourg, France.

Abstract: Random spin models play a key role in our understanding of disorder and complex many-body systems. Two all-to-all interacting, disordered models have now been realized using a cavity quantum electrodynamics platform. All-to-all interacting, disordered quantum many-body models have a wide range of applications across disciplines, from spin glasses in condensed-matter physics over holographic duality in high-energy physics to annealing algorithms in quantum computing. Typically, these models are abstractions that do not find unambiguous physical realizations in nature. Here we realize an all-to-all interacting, disordered spin system by subjecting an atomic cloud in a cavity to a controllable light shift. Adjusting the detuning between atom resonance and cavity mode, we can tune between disordered versions of a central-mode model and a Lipkin-Meshkov-Glick model. By spectroscopically probing the low-energy excitations of the system, we explore the competition of interactions with disorder across a broad parameter range. We show how disorder in the central-mode model breaks the strong collective coupling, making the dark-state manifold cross over to a random distribution of weakly mixed light-matter, ’grey’, states. In the Lipkin-Meshkov-Glick model, the ferromagnetic finite-sized ground state evolves towards a paramagnet as disorder is increased. In that regime, semi-localized eigenstates emerge, as we observe by extracting bounds on the participation ratio. These results present substantial steps towards freely programmable cavity-mediated interactions for the design of arbitrary spin Hamiltonians.

Journal/Review: NATURE PHYSICS

Volume: 19 (8)      Pages from: 1128  to: +

More Information: Open access funding provided by EPFL Lausanne
KeyWords: Quantum Phase-transition; Many-body Localization; Anderson Localization; Ultracold Atoms; Simulations; Gas
DOI: 10.1038/s41567-023-02033-3

ImpactFactor: 17.600
Citations: 13
data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-11-24
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