Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 5: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts - Part 1
TT 5.5: Vortrag
Montag, 27. März 2006, 10:45–11:00, HSZ 304
Non-local effects in transport through coupled quantum dots — •Jasmin Aghassi1,2, Axel Thielmann1,2, Matthias Hettler1, and Gerd Schön1,2 — 1Forschungszentrum Karlsruhe, INT, Postfach 3640, 76021 Karlsruhe — 2Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe
We study current and shot noise in sequential tunneling through non-local systems such as two and three coupled quantum dots (“artificial molecules”). The dots are fully coherent among each other and weakly coupled to the electrodes via the interfacial dots. In the case of two coupled quantum dots various sources of asymmetry, i.e. non-resonant dots or asymmetric couplings lead eventually to super-Poissonian noise and negative differential counductance above the sequential tunneling threshold. In contrast, the three dot system displays interesting super-Poissonian behavior even in fully symmetric situations due to a complex spin-related mechanism. Fano factors may thus be largely enhanced up to values of 100. Such strong enhancement should allow direct experimental detection of shot noise in lateral quantum dot experiments. Within our diagrammatic approach we further discuss the influence of cotunneling processes on the transport characteristics in these non-local systems.
[1] J. Aghassi, A. Thielmann, M.H. Hettler, and G. Schön, cond-mat/0505345