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TT: Fachverband Tiefe Temperaturen

TT 18: Nanoelectronics I - Quantum Dots, Wires, Point Contacts

TT 18.12: Vortrag

Mittwoch, 28. März 2007, 17:00–17:15, H19

The conductance of a multi-mode ballistic ring: Beyond Landauer and Kubo — •Swarnali Bandopadhyay¹, Yoav Etzioni², and Doron Cohen² — ¹MPIPKS Dresden, Nöthnitzer Str. 38, 01187 Dresden — ²Department of Physics, Ben-Gurion University, Beer-Sheva 84105, Israel

The calculation of the conductance of ballistic rings requires a theory that goes well beyond the Kubo-Drude formula [S. Bandopadhyay, Y. Etzioni and D. Cohen, Europhys. Lett. 76, 739 (2006)]. Assuming mesoscopic circumstances of very weak environmental relaxation, the conductance is much smaller compared with the naive expectation. Namely, the electro-motive force induces an energy absorption with a rate that depends crucially on the possibility to make connected sequences of transitions. Thus the calculation of the mesoscopic conductance is similar to solving a percolation problem. The percolation is in energy space rather than in real space. Non-universal structures and sparsity of the perturbation matrix cannot be ignored. The latter are implied by lack of quantum-chaos ergodicity in ring shaped ballistic devices.