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TT: Fachverband Tiefe Temperaturen

TT 10: Poster Session: Superconductivity

TT 10.45: Poster

Montag, 14. März 2011, 14:00–18:00, P4

Tunable double well potential for fractional Josephson two-vortex molecule — •Dennis M. Heim¹, Karl Vogel¹, Wolfgang P. Schleich¹, Edward Goldobin², Dieter Koelle², and Reinhold 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).