Events in Physics

Environmental dynamics and the emergence of noncanonical equilibrium states in open quantum systems

Standard open quantum system methods eliminate all information on the environmental state in order to provide a tractable description of the system dynamics. By incorporating a collective coordinate of the environment into the system Hamiltonian, we develop a formalism that circumvents this limitation, allowing straightforward access to important properties of the environmental dynamics that are typically inaccessible using other methods. Focussing on the non-perturbative problem of a quantum system coupled to a low frequency environment, we reveal that the canonical thermal system steady-state predicted by standard perturbative methods is almost always incorrect. We show this to be due to the generation of long-lasting system-environment correlations that persist into the steady-state, leading also to non-Gaussian environmental states. We can, nevertheless, fully characterise the system-environment steady-state as a thermal state of the combined system-collective coordinate Hamiltonian. We outline how the resulting noncanonical system steady-state could be investigated in ongoing experiments to study deviations from canonical thermodynamics, with direct relevance to molecular and solid-state nanosystems.