Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 3: Transport: Quantum Dots, Quantum Wires, Point Contacts

TT 3.7: Vortrag

Montag, 20. März 2017, 11:00–11:15, HSZ 201

Dark states in spin-resolved transport through triple quantum dots — •Kacper Wrześniewski and Ireneusz Weymann — Faculty of Physics, Adam Mickiewicz University in Poznań, ul. Umultowska 85, 61-614 Poznań, Poland

We analyze the effect of dark states on spin-dependent transport properties of a triple quantum dot system. The considered quantum dot device is assumed to form a triangular geometry, resembling a simple planar molecule, and is weakly coupled to external ferromagnetic electrodes. The transport characteristics are studied by means of the real-time diagrammatic technique up to the second order of the perturbation theory with respect to the dot-lead coupling.

We examine transport in regimes where both one- and two-electron dark states occur, leading to the current rectification, negative differential conductance and super-Poissonian shot noise. Moreover, we compare the behavior of the tunnel magnetoresistance between different dark state regimes and in Coulomb blockade regime, predicting that the measurement of this quantity may indicate the mechanism of current blockade in similar devices. Finally, we consider the influence of external magnetic field on the formation of dark states and analyze how magnetic field can be used to manipulate coherent population trapping in the system.