Memory Effects

Philip Taranto

This thesis studies memory effects in quantum stochastic processes with memory. In particular, we develop notions of memory length and memory strength that allow for an unambiguous examination of the structure of memory effects that can arise in quantum processes.

Philip Taranto

This thesis studies memory effects in quantum stochastic processes with memory. In particular, we develop notions of memory length and memory strength that allow for an unambiguous examination of the structure of memory effects that can arise in quantum processes.

Chen-Yen Lai, Chih-Chun Chien

Dynamics of a system generally depends on its initial state and how the system is driven, but in many-body systems the memory is usually averaged out during evolution. Here, interacting quantum systems without external relaxations are shown to retain long-time memory effects in steady states. To identify memory effects, we first show quasi-steady state currents form in finite, isolated Bose and Fermi Hubbard models driven by interaction imbalance and they become steady-state currents in the thermodynamic limit. By comparing the steady state currents from different initial states or ramping rates of the imbalance, long-time memory effects can be quantified. While the memory effects of initial states are more ubiquitous, the memory effects of switching protocols are mostly visible in interaction-induced transport in lattices. Our simulations suggest the systems enter a regime governed by a generalized Fick's law and memory effects lead to initial-state dependent diffusion coefficients. We also identify conditions for enhancing memory effects and discuss possible experimental implications.

Gerard T. Higgins