Eigenstate thermalization in local systems from a generalized Wigner ensemble description

The eigenstate thermalization hypothesis (ETH) formulates a general connection between statistical physics and quantum mechanics. It 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 an approach to understand how thermal properties emerge in exact eigenstates of locally coupled random spin Hamiltonians. In particular, we report on random matrix computations for the reduced density matrix within a generalized Wigner ensemble. The analytical findings are compared to numerical exact diagonalization results.