Numerical exploration of the physical origin of eigenstate thermalization

The eigenstate thermalization hypothesis (ETH) formulated by Deutsch and Srednicki proposes that under the absence of integrability, a generic eigenstate of an isolated, interacting quantum system behaves as a thermal bath to its subsystems. In this talk, we present numerical results on a random spin-1/2 lattice with local couplings to understand the mechanism of eigenstate thermalization on a more fundamental level. We explore the mechanism by which individual eigenstates can exhibit thermal properties and connect it to the behavior of the reduced density matrix of a small subsystem.