Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 1
TT 6.7: Vortrag
Montag, 26. März 2012, 11:15–11:30, BH 334
Zero-frequency noise in adiabatically driven quantum systems — •Roman-Pascal Riwar1,2, Janine Splettstoesser1,2, and Jürgen König3 — 1Institut für Theorie der Statistischen Physik, RWTH Aachen University, D-52056 Aachen, Germany — 2JARA-Fundamentals of Future Information Technology — 3Theoretische Physik, Duisburg-Essen and CeNIDE, D-47048 Duisburg, Germany
We investigate current-current correlations of adiabatic quantum pumps, taking into account Coulomb interaction. We make use of a real-time diagrammatic approach within a perturbative expansion in the tunnel coupling to the reservoirs and extend a treatment of adiabatic time dependence (Splettstoesser et al., PRB 2006) to the calculation of current noise.
We consider the case of a single-level quantum dot coupled to two leads where charge pumping arises by applying two out-of-phase time-dependent parameters, such as the energy levels, the bias or the tunnel couplings. While the instantaneous contribution to the noise confirms the results of the stationary case (Thielmann et al., PRL 2005), new properties are found in the adiabatic correction, i.e., the pumping noise. If the leads are at equilibrium at any time, the adiabatic correction of the Fano factor has a stable shape independently of the choice of the pumping parameters, also beyond the sequential tunneling regime. It provides additional information on the tunnel-coupling and the electron-hole symmetric point. When including a time-dependent finite bias, we find that there can be pumping noise even if there is zero pumped charge, due to a finite tunnel coupling asymmetry.