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B. Kubala, G. Johansson, and J. Konig
Sytems of coupled single-electron transistors show a rich variety of physics, due to modification of charging effects on one of the islands by capacitive and tunnel coupling to the others. We developed a method to study electron transport through such systems, driven by nonlinear thermal or voltage bias. Based on real-time transport theory, all diagrams up to second order in tunneling coupling are automatically generated and calculated, thus capturing all different sequential and cotunneling processes. In particular, we find a class of cotunneling processes involving correlated tunneling onto two different islands. These can be linked to tunneling rates for an SET in a noisy environment -constituted by another SET- as calculated within a P(E) theory. Thermopower experiments measure the average energy of the particles constituting the current. Therefore the thermopower of single-electron transport through a metallic island can serve as a tool for investigating the renormalization of the charging energy. This renormalization stems from second order processes, which are not included in a standard-cotunneling description of thermopower. |
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