Abstract
We study the validity of the fluctuation-dissipation theorem for an isolated quantum system of harmonically trapped dipolar molecules taken out of equilibrium by means of a quench, a sudden change in the Hamiltonian parameters. We find that the integrability of the system plays a crucial role in the validity of the fluctuation-dissipation theorem. Namely, the system thermalizes according to the eigenstate thermalization hypothesis and the theorem holds if the system is nonintegrable after the quench. However, it fails if the system is integrable, unless the initial state is an eigenstate of a nonintegrable Hamiltonian, in which case the system still thermalizes despite the eigenstate thermalization hypothesis failing to describe it.
Highlights
Non-equilibrium dynamics of isolated quantum many-body systems have attracted a great deal of attention in recent years, partly owing to the significant experimental advancements being made in the simulation of such systems by confining, and controlling the interactions of, ultracold atomic gazes
To generate non-equilibrium dynamics, these systems can be prepared in an initial state that is not an eigenstate of the Hamiltonian being simulated, a process called quenching
The fluctuation-dissipation theorem (FDT) is valid as long as the perturbation is in the linear response regime and that the system is in thermal equilibrium
Summary
Ehsan Khatami, University of California, Davis Guido Pupillo, Université de Strasbourg Mark Srednicki, University of California, Santa Barbara Marcos Rigol, The Pennsylvania State University. This work is licensed under a Creative Commons CC_BY International License.
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