1303.7441 (Loïc Freton et al.)

Out-of-equilibrium properties and non-linear effects for interacting
quantum impurity systems in their strong coupling regime    [PDF]

Loïc Freton, Edouard Boulat

We build an exact description of out-of-equilibrium fixed points in quantum impurity systems, that is able to treat time-dependent forcing. We then show that exact analytical out-of-equilibrium results can be obtained in interacting quantum impurity systems in their strong coupling regime, provided they are integrable \emph{at} equilibrium and they only allow for integer charge hopping at low energy. For a large class of local operators, including currents (of charge, energy, ...), we show that out-of-equilibrium correlators can be obtained as equilibrium correlators of effective operators. We explicitly show that out-of-equilibrium properties are universal, i.e. they depend on the microscopic details through a \emph{single} energy scale. We apply our approach to the Interacting Resonant Level model, and obtain the expansion of the universal scaling function for the charge current as a function of voltage, temperature, and frequency, up to order seven.

View original: http://arxiv.org/abs/1303.7441