Auxiliary master equation approach for strongly correlated quantum impurities out of equilibrium and applications within Dynamical Mean Field Theory

The auxiliary master equation approach [1,2] allows for an accurate and efficient treatment of correlated impurities out of equilibrium. The method is based upon a mapping onto an auxiliary open quantum system in which the impurity is coupled to bath orbitals as well as to a Markovian environment. The intervening auxiliary orbitals allow for a treatment of non-Markovian dynamics at the impurity. The time dependence of this auxiliary system is controlled by a Lindblad master equation whose parameters are used to optimize the mapping, which becomes exponentially exact upon increasing the number of bath orbitals [3]. Green's functions are evaluated by (non-hermitian) Lanczos exact diagonalisation [2] or by matrix-product states (MPS) [4].
Applications to nonequilibrium Dynamical Mean Field Theory (DMFT) [5] and a generalisation to treat periodically driven quantum systems within Floquet theory will be discussed. We present novel results of the (periodic-)steady state properties of an electric field driven mott insolator connected to non-interacting leads as a simplified model of a so called ``Mott Solar Cell''. The latter beeing a candidate of a highly efficient solar cell because of carier proliferation due to impact ionisation processes[6-8].

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