Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: Quantum Dots, Quantum Wires, Point Contacts

TT 22.13: Vortrag

Dienstag, 17. März 2020, 12:45–13:00, HSZ 201

Colortronics in Triple Quantum Dots — •Martin Maurer1, Jürgen König2, and Herbert Schoeller11Institut für Theorie der Statistischen Physik, RWTH Aachen and JARA - Fundamentals of Future Information Technology — 2Theoretische Physik, Universität Duisburg-Essen and CENIDE

We study coherence effects in a three-level spinless quantum dot with strong local Coulomb interaction coupled weakly to metallic reservoirs. Employing the generators of the SU(3), we decompose the reduced density matrix in the subspace of single occupation. It is then characterized by an eight-dimensional real vector that is the analogue to the vector of average (iso-)spin in a two-level setup. We call this vector the dot color. In the high-temperature limit we derive a kinetic equation for the dot color to first order in the dot-lead coupling. This equation can be decomposed into an accumulation, a relaxation, and a rotation component, providing intuitive insight into the dot dynamics. We discuss the inclusion of spin and a generalization to an arbitrary number of dot levels.

Regarding the three-level case, we propose an experimental setup that produces a complete current blockade in nonlinear response for degenerate levels. This blockade is based on the formation of a coherent superposition of dot levels and is broken when dot energies are detuned. The resulting current-detuning curve highlights the role of coherence between all three dot levels in the blockade.

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