https://doi.org/10.1140/epjb/e2013-30770-7
Regular Article
Stroboscopic wave packet description of time-dependent currents through ring-shaped nanostructures
1 Department of Physics, Institute of
Nuclear and Physical Engineering, Faculty of Electrical Engineering and Information
Technology, Slovak University of Technology in Bratislava,
Ilkovičova 3, 81219
Bratislava,
Slovakia
2 European Theoretical Spectroscopical
Facility, Department of Physics, University of York, Heslington, York
YO10 5DD,
UK
a e-mail: martin.konopka@stuba.sk
Received:
22
August
2012
Received in final form:
24
December
2012
Published online:
25
March
2013
We present an implementation of a new method for explicit simulations of time-dependent electric currents through nanojunctions. The method is based on unitary propagation of stroboscopic wave packet states and is designed to treat open systems with fluctuating number of electrons while preserving full quantum coherence throughout the whole infinite system. We demonstrate the performance of the method on a model system consisting of a ring-shaped nanojunction with two semi-infinite tight-binding leads. Time-dependent electron current responses to abrupt bias turn-on or gate potential switching are computed for several ring configurations and ring-leads coupling parameters. The found current-carrying stationary states agree well with the predictions of the Landauer formula. As examples of genuinely time-dependent process we explore the presence of circulating currents in the rings in transient regimes and the effect of a time-dependent gate potential.
Key words: Computational Methods
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2013