Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 31: Poster I: Devices, Quantum Dots and Quantum Wires
HL 31.30: Poster
Tuesday, March 23, 2010, 18:30–20:30, Poster D1
Transient characteristics of a parabolic quantum wire quenched by one or two QPCs — •Cosmin M. Gainar1, Valeriu Moldoveanu2, Andrei Manolescu3, and Vidar Gudmundsson1 — 1Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland — 2National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele, Romania — 3School of Science and Engineering, Reykjavik University, Kringlan 1, 103 Reykjavik, Iceland
We describe theoretically the time-dependent transport through a “sample system” defined as a parabolic quantum wire of a finite length coupled to two semi-infinite leads. The sample may also include one or two embedded quantum point contacts (QPCs) created with Gaussian potentials. The coupling between the leads and the sample is described by a non-local kernel connecting the wave functions from both sides and by a time-dependent coupling function with a smooth onset at the initial moment t=0. Starting with an initial occupation of the sample we calculate the time-dependent currents by solving the generalized master equation of the reduced density operator in the presence of a bias. We investigate and discuss the charge accumulation in the sample, the transient currents along the leads, and the final steady state. We use various initial states of the sample and various coupling functions. The embedded QPCs may considerably slow down the transient processes and affect the shape of the propagating signal.