Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 101: Transport - Poster Session

TT 101.30: Poster

Donnerstag, 3. April 2014, 15:00–19:00, P2

Resonance-assisted tunneling of Cooper pairs — •Pierre-Luc Dallaire-Demers and Frank Wilhelm-Mauch — Universität des Saarlandes, Saarbrücken, Deutschland

Superconducting tunnel junctions can be designed to have femtofarad capacitance with their charging energy larger than their Josephson energy E_J. When biased with a constant voltage V below the superconducting gap, the supercurrent starts to oscillate at a frequency ω = 2e V/ℏ. If the junction is capacitively coupled to an external electromagnetic environment, a net current appears through the junction as Cooper pairs tunnel and emit photons in the external modes, allowing for the spectroscopy of the environment. We investigate the situation where Cooper pair tunneling is coupled to a perfect LC mode, high order processes such as sequential coherent tunnel events involving many photons and pairs can contribute to the net current, departing significantly from the traditional picture of incoherent tunneling given by P(E) theory. At low temperature, different regimes can be observed varying with the ratio of the mode frequency and the tunneling rate. We present the main diagrams contributing to each of those regimes and compute the asymptotic current in each case. Finally, the full perturbative series in E_J is cast in terms of a P(E) framework in order to extend the method to more general environmental impedances.