Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs
TT 17.8: Vortrag
Montag, 31. März 2014, 17:00–17:15, HSZ 201
Quantum Brownian motion in an oscillating tilted periodic potential: application to a Josephson junction under microwave irradiation in the dual regime — •Angelo Di Marco1, Gianluca Rastelli2, and Frank W. J. Hekking1 — 1LPMMC-CNRS, Université Joseph Fourier, 25 Avenue des Martyrs BP166 38042, Grenoble Cedex, France — 2Zukunftskolleg, Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
We study a current-biased Josephson junction in the presence of an applied microwave field and influenced by an external electromagnetic environment. This problem can be mapped onto the one of a quantum Brownian particle moving in a tilted periodic potential under the effect of an oscillating force. We focus on the regime where the junction’s Josephson energy EJ dominates its charging energy EC. In this case, it is the dynamics of the so-called quasi-charge that accounts for the current-voltage characteristic of the junction. Using a full quantum approach, we study numerically and analytically the I-V curve at low temperature. In particular, we analyze the role of the quantum fluctuations on the theoretically expected Shapiro steps for current. We compare our results with the one based on a classical approach for the dynamics of the quasi-charge.