2025/03/05 by Lucas Winter, Winter, Lucas, Pietro Brighi +3 · 2 citations
Physics and Astronomy · #Quantum many-body systems #Cold Atom Physics and Bose-Einstein Condensates #Physics of Superconductivity and Magnetism
paper · pdf · doi:10.48550/arxiv.2503.03801
Quantum systems with strong long-range interactions are thought to resist thermalization because of their discrete energy spectra. We show that applying a staggered magnetic field to a strong long-range Heisenberg antiferromagnet restores thermalization for a large class of initial states by breaking permutational symmetry. Using self-consistent mean-field theory and exact diagonalization, we reveal that the energy spectrum, while composed of discrete subspaces, collectively forms a dense spectrum. The equilibration time is independent of system size and depends only on the fluctuations in the initial state. For initial states at low to intermediate energies, the long-time average aligns with the microcanonical ensemble. However, for states in the middle of the spectrum the long-time average depends on the initial state due to quantum scar-like eigenstates localized at unstable points in classical phase space. Our results can be readily tested on a range of experimental platforms, including Rydberg atoms or optical cavities.