Majidy Shayan
Institute for Quantum Computing, University of Waterloo, Waterloo, ON, Canada.
Department of Physics, Harvard University, Cambridge, MA, USA.
Nat Commun. 2024 Sep 20;15(1):8246. doi: 10.1038/s41467-024-52588-9.
Studying noncommuting conserved quantities, or 'charges,' has revealed a conceptual puzzle: noncommuting charges hinder thermalization in some ways yet promote it in others. While many quantum systems thermalize according to the Eigenstate Thermalization Hypothesis (ETH), systems with 'dynamical symmetries' violate the ETH and exhibit non-stationary dynamics, preventing them from equilibrating, much less thermalizing. We demonstrate that each pair of dynamical symmetries corresponds to a specific charge. We find that introducing new charges that do not commute with existing ones disrupts these symmetries, thereby eliminating non-stationary dynamics and facilitating thermalization. We illustrate this behavior across various models, including the Hubbard model and Heisenberg spin chains. Our findings demonstrate that noncommuting charges can enhance thermalization by reducing the number of local observables that thermalize according to the ETH.
对非对易守恒量(即“荷”)的研究揭示了一个概念性难题:非对易荷在某些方面会阻碍热化,但在其他方面又会促进热化。虽然许多量子系统根据本征态热化假说(ETH)进行热化,但具有“动力学对称性”的系统违反ETH并表现出非平稳动力学,从而阻止它们达到平衡,更不用说热化了。我们证明,每一对动力学对称性都对应一个特定的荷。我们发现,引入与现有荷不对易的新荷会破坏这些对称性,从而消除非平稳动力学并促进热化。我们在包括哈伯德模型和海森堡自旋链在内的各种模型中展示了这种行为。我们的研究结果表明,非对易荷可以通过减少根据ETH热化的局部可观测量的数量来增强热化。