- Response theory for nonequilibrium steady-states of open quantum systems | arXiv:2010.03929 (2020)
- 12:00 am - 11:59 pm
- December 12, 2020
We introduce a response theory for open quantum systems described by the Lindblad-Gorini-Kossakowski-Sudarshan formalism evolving under equilibrium or nonequilibrium conditions. We find that the response of the system to a small perturbation is not simply related to a correlation function within the system, unlike traditional linear response theory in closed systems or expectations from the fluctuation-dissipation theorem. In limiting cases, when the perturbation is small relative to the coupling to the surroundings or when it does not lead to a change of the eigenstructure of the system, a perturbative expansion exists where the response function is related to a sum of a system correlation functions and additional forces induced by the surroundings. Away from these limiting regimes however, the secular approximation results in a singular response that cannot be captured within the traditional approach, but can be described by reverting to a microscopic Hamiltonian description. These findings are illustrated by explicit calculations in coupled qubits and anharmonic oscillators in contact with bosonic baths at different temperatures.
A. Levy, E. Rabani, D.T. Limmer