Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: Transport: Poster Session

TT 22.1: Poster

Mittwoch, 27. Februar 2008, 14:00–18:00, Poster B

Time-resolved Electron Transport through Quantum Dot Systems — •Alexander Croy and Ulf Saalmann — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany

The investigation of time-resolved currents in mesoscopic devices has gained a lot of interest over the past few years. This is not only because of the potential application to quantum-computing but also due to the advent of new experiments specifically looking into time-dependent electron transport.

In this context we study theoretically the time-resolved electric currents flowing through single and double quantum dots that are subject to a voltage pulse. To this end we numerically solve a quantum master equation (QME) for the many-body density matrix describing the state of the quantum dot system. This allows us to access the time-resolved occupation and the currents flowing through the system. As a first application we show for the non-interacting resonant level model a comparison of our results with non-equilibrium Green function calculations [1]. Furthermore, we revisit a recent experiment [2] with double quantum dots and analyse it by means of the QME. For this purpose we focus on the number of pulse-induced tunneling electrons as a function of pulse length. In addition to numerical results we propose a simple analytical model which allows for the interpretation of the characteristic features observed.

[1] N. S. Wingreen et al., Phys. Rev. B48, 8487 (1993)

[2] T. Hayashi et al., Phys. Rev. Lett. 91, 226804 (2003)