Out-of-equilibrium quantum magnetism and thermalization in a spin-3 many-body dipolar lattice system

Steven Lepoutre (1) , Joahnnes Schachenmayer (2, 3) , Lucas Gabardos (1) , Bihui Zhu (4, 5) , Bruno Naylor (1) , Etienne Maréchal (1) , Olivier Gorceix (1) , Ana Maria Rey (4) , Laurent Vernac (1) , Bruno Laburthe-Tolra (1)

1 LPL - Laboratoire de Physique des Lasers
2 ISIS - Institut de Science et d'ingénierie supramoléculaires
3 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
4 University of Colorado [Boulder]
5 ITAMP - Institute for Theoretical Atomic, Molecular and Optical Physics [Cambridge]

Understanding quantum thermalization through entanglement build up in isolated quantum systems addresses fundamental questions on how unitary dynamics connects to statistical physics. Spin systems made of long-range interacting atoms offer an ideal experimental platform to investigate this question. Here, we study the spin dynamics and approach towards local thermal equilibrium of a macroscopic ensemble of S = 3 chromium atoms pinned in a three dimensional optical lattice and prepared in a pure coherent spin state, under the effect of magnetic dipole-dipole interactions. Our isolated system thermalizes under its own dynamics, reaching a steady state consistent with a thermal ensemble with a temperature dictated from the system's energy. The build up of quantum correlations during the dynamics is supported by comparison with an improved numerical quantum phase-space method. Our observations are consistent with a scenario of quantum thermalization linked to the growth of entanglement entropy.

Domaines: Electromagnétisme

Steven Lepoutre, Joahnnes Schachenmayer, Lucas Gabardos, Bihui Zhu, Bruno Naylor, et al.. Out-of-equilibrium quantum magnetism and thermalization in a spin-3 many-body dipolar lattice system. Nature Communications, 2019, 10, ⟨10.1038/s41467-019-09699-5⟩. ⟨hal-03413697⟩