Dynamics of thermalization and decoherence of a nanoscale system

TL;DR

This paper investigates how a nanoscale quantum system thermalizes and decoheres when coupled strongly to a quantum bath, revealing two distinct decay regimes and confirming the eigenstate thermalization hypothesis.

Contribution

It introduces a random matrix model to analytically describe the thermalization and decoherence dynamics of a nanoscale system coupled to a quantum bath, identifying two robust temporal regimes.

Findings

Initial Gaussian decay of coherence

Exponential tail in thermalization process

Decay towards Gibbs ensemble consistent with eigenstate thermalization hypothesis

Abstract

We study the decoherence and thermalization dynamics of a nanoscale system coupled nonperturbatively to a fully quantum-mechanical bath. The system is prepared out of equilibrium in a pure state of the complete system. We propose a random matrix model and show analytically that there are two robust temporal regimes in the approach of the system to equilibrium --- an initial Gaussian decay followed by an exponential tail, consistent with numerical results on small interacting lattices [S. Genway, A.F. Ho and D.K.K. Lee, Phys. Rev. Lett. 105, 260402 (2010)]. Furthermore, the system decays towards a Gibbs ensemble in accordance with the eigenstate thermalization hypothesis.