Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 29: Transport: Quantum Dots, Wires, Point Contacts 3 (jointly with HL)

TT 29.7: Talk

Tuesday, March 12, 2013, 11:30–11:45, H20

Transport across an Anderson quantum dot in the intermediate coupling regime — •Johannes Kern and Milena Grifoni — Universität Regensburg, Institut für Theoretische Physik, 93040 Regensburg

We describe transport across a quantum dot coupled to leads at different chemical potentials. For this we use the master equation approach. The current is determined via the reduced density matrix by "kernels", the contributions to those are visualized by diagrams. Because of the huge variety and complexity of the diagrams, we take into account only the diagrams within a selection which we call the "dressed second order" (DSO)[1]. We apply this to the case of the single impurity Anderson model and show that the DSO allows the description of various effects: the transition from thermally broadened to tunnel broadened peaks of the linear conductance as well as of the differential conductance as function of the bias; the shift of the conductance peaks with temperature; a zero bias anomaly in the differential conductance; the splitting of this anomaly in case a magnetic field is applied. To conclude, we see the strength of the DSO in its simplicity as well as in its applicability to various problems including the transport across more complicated quantum dots.
[1] J. Kern and M. Grifoni, arXiv:1209.4995.