SKM 2023 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 38: Nonequilibrium Quantum Many-Body Systems II (joint session TT/DY)

TT 38.13: Talk

Wednesday, March 29, 2023, 18:15–18:30, HSZ 204

Configuration interaction based nonequilibrium steady state impurity solver — •Daniel Werner, Jan Lotze, and Enrico Arrigoni — ITPCP, Graz, Austria

We present a solver for correlated impurity problems out of equilibrium based on a combination of the so-called auxiliary master equation approach (AMEA) and the configuration interaction (CI) expansion. Within AMEA one maps the original impurity model onto an auxiliary open quantum system with a restricted number of bath sites which can be addressed by numerical many-body approaches such as ED or MPS. While the mapping becomes exponentially more accurate with increasing number of bath sites, ED implementations are severely limited due to the fast increase of the Hilbert space dimension for open systems, and the MPS solver typically requires rather long runtimes. Here, we propose to adopt a CI approach to solve numerically the correlated auxiliary open quantum system. This allows access to a larger number of bath sites at lower computational costs than for ED. We benchmark the approach with NRG results in equilibrium and with MPS out of equilibrium. We evaluate the current, the conductance as well as the Kondo peak and its splitting. We obtain a rather accurate scaling of the conductance as a function of the bias voltage and temperature rescaled by TK for moderate to strong interactions in a wide range of parameters. The approach combines the fast runtime of ED with an accuracy close to the one achieved by MPS making it an attractive solver for nonequilibrium DMFT. (arXiv: 2210.09623)