Modern Concepts of Quantum Equilibration Do Not Rule Out Strange Relaxation Dynamics

Abstract

Numerous pivotal concepts have been introduced to clarify the puzzle of relaxation and/or equilibration in closed quantum systems. All of these concepts rely in some way on specific conditions on Hamiltonians $H$, observables $A$, and initial states $\rho$ or combinations thereof. We numerically demonstrate and analytically argue that there is a multitude of pairs $H,A$ that meet said conditions for equilibration and generate some "typical" expectation value dynamics which means, $⟨A(t)⟩\propto f(t)$ approximately holds for the vast majority of all initial states. Remarkably we find that, while restrictions on the $f(t)$ exist, they do not at all exclude $f(t)$ that are rather adverse or "strange" regarding thermal relaxation.

arXiv comment12 pages, 6 figures

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