Off-diagonal matrix elements of local operators in many-body quantum systems
Off-diagonal matrix elements of local operators in many-body quantum systems
In the time evolution of isolated quantum systems out of equilibrium, local observables generally relax to a long-time asymptotic value, governed by the expectation values (diagonal matrix elements) of the corresponding operator in the eigenstates of the system. The temporal fluctuations around this value, response to further perturbations, and the …