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Dual current anomalies and quantum transport within extended reservoir simulations



Gabriela Wojtowicz, Justin E. Elenewski, Marek Rams, Michael P. Zwolak


Quantum transport simulations are rapidly evolving, including the development of well–controlled tensor network techniques for many– body transport calculations. One particularly powerful approach combines matrix product states with extended reservoirs — an open system methodology where relaxation maintains a chemical potential or temperature drop. Due to the presence of external relaxation, there is a simulation–analog of Kramers' turnover, with relaxation-controlled currents for small and large relaxation strength. Only between these regimes can the natural (Landauer or Meir-Wingreen) conductance control the simulation result. We show here that anomalous transport characteristics can appear when employing this methodology even with moderate relaxation. While features, such as oscillations on top of the normal turnover, are already known to arise from band structure and gap states, we demonstrate that small steady-state currents unveil two anomalies, one due to virtual transitions and the other due to unphysical broadening of the occupied density of states. This refines the turnover picture of simulation and shows that there are five standard transport regimes. Moreover, there is an exact duality between weak–to–moderate and moderate–to–strong relaxation anomalies for a single–site impurity. These regimes further constrain the computational parameters that are needed to properly represent physical behavior in the continuum limit.
Physical Review B


Wojtowicz, G. , Elenewski, J. , Rams, M. and Zwolak, M. (2021), Dual current anomalies and quantum transport within extended reservoir simulations, Physical Review B, [online],, (Accessed April 19, 2024)
Created October 19, 2021, Updated December 16, 2021