Marianna Sorba — CNR-INO Trieste #
Quantum quenches with long-range interactions #
The remarkable predictive power of the asymptotic state theory applied to nonequilibrium quantum dynamics relies on the ability to the cast the problem in the formalism of asymptotic states of quantum field theory, a framework which allowed the general analysis of systems with short-range interactions. At the same time, numerical studies of long-range interacting spin chains revealed dynamical features — including undamped oscillations at large time — quite analogous to those observed in short-range systems, suggesting that the domain of application of the asymptotic state theory could be further extended. Despite the additional analytical difficulties posed by long-range interactions, we show for the first time that such an extension can indeed be achieved in the case of quantum quenches. Considering d-dimensional homogeneous systems, we treat the long-range interaction as switched on by the quench and perform the derivation within the basis of asymptotic states of the short-range interacting pre-quench theory. This approach allows us to analytically determine the post-quench state and the one-point functions of local observables and to characterize their large-time behavior.