Thermalization in a model of enhanced memory capacity

Abstract

We study thermalization within a quantum system with an enhanced capacity to store information. This system has been recently introduced to provide a prototype model of how a black hole processes and stores information. We perform a numerical finite-size analysis of this isolated quantum system and find indications that its information-carrying subsystem approaches thermality in the large system-size limit. The results lead us to suggest a novel thermalization mechanism. The corresponding distinguishing characteristic is that for a large class of physically meaningful non-equilibrium initial states $| \text{in} \rangle$, a few-body observable $\hat{A}$ thermalizes despite unignorable correlations between the fluctuations of its eigenstate expectation values $\langle \alpha | \hat{A} | \alpha \rangle$ in the eigenstate basis of the model $\left\{ | \alpha \rangle \right\}$ and the fluctuations of the squared magnitudes of the coefficients $|C_{\alpha}|^2 = |\langle \alpha | \text{in} \rangle |^2$.