# Berlin 2015 – wissenschaftliches Programm

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# TT: Fachverband Tiefe Temperaturen

## TT 21: Superconductivity: Poster Session

### TT 21.48: Poster

### Montag, 16. März 2015, 15:00–18:00, Poster B

**How to identify quantum effects in a driven current-biased JJ** — •Harald Losert, Karl Vogel, and Wolfgang P. Schleich — Institut für Quantenphysik, Universität Ulm, D-89069 Ulm, Germany

The phase difference in a current-biased Josephson junction behaves like a particle in a tilted washboard potential. There has been a huge interest in the behaviour of such a particle - in particular in the case of an external periodic driving field - since the escape of the phase-particle corresponds to the voltage switching of the associated Josephson junction. Experimentally, the bias current is increased until the voltage state changes. Quantum mechanically it can be explained as tunneling from the ground state, or from an excited state. However, the resulting switching current distribution can also be explained classically [1]. Up to now, the distinction between quantum and classical effects is still an open question in many implementations of Josephson junctions.

Based on this discussion, we present numerical simulations of the quantum mechanical and classical time evolution of such a system. In particular, we contrast the resulting switching current distributions.

[1] Grønbech-Jensen *et al.*, *Phys. Rev. Lett.* **95**, 067001 (2005).