Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 29: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs 1
TT 29.1: Vortrag
Mittwoch, 28. März 2012, 15:00–15:15, H 2053
Tunable double well potential for fractional Josephson two-vortex molecule — •D. M. Heim1, K. Vogel1, W. P. Schleich1, E. Goldobin2, D. Koelle2, and R. Kleiner2 — 1Institut für Quantenphysik, Universität Ulm, D-89069 Ulm, Germany — 2Physikalisches Institut and Center for Collective Quantum Phenomena, Universität Tübingen, D-72076 Tübingen, Germany
We study a fractional Josephson two-vortex molecule in a long Josephson 0-κ-2κ junction. The ground state is degenerate, corresponding to two configurations with topological charges (κ, κ−2π) and (κ−2π, κ) of fractional vortices. We propose to use such a system to study macroscopic quantum phenomena involving fractional vortices. Similar to the previous proposal based on a 0-π-0 junction [1], the two-vortex-molecule states can be mapped to a double well potential. However, by changing the value of κ during experiment we are able to tune the energy barrier separating the two classical ground states. We calculate characteristic properties (e.g. barrier height, eigenfrequency) and demonstrate that a controlled transition into the quantum regime is possible in such a system.
[1] E. Goldobin et al., Phys. Rev. B 72, 054527 (2005).