Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 8: Posters Transport

TT 8.37: Poster

Friday, March 4, 2005, 14:00–18:00, Poster TU C

Long Josephson junctions as vortex qubits — •A. Kemp, A. N. Price und A. V. Ustinov — Physikalisches Institut III, Universität Erlangen-Nürnberg, Erwin-Rommel-Str 1., 91058 Erlangen, Germany

We have investigated the properties of Josephson vortices in annular Josephson junctions of circumference comparable to the Josephson penetration depth, at millikelvin temperatures. The fluctuation-induced activation of these vortices exhibits a systematic magnetic field and temperature dependence. We evaluate the height of the potential barrier between two spatially separated vortex states in long heart-shaped junctions. Reproducibility of the initial vortex state is guaranteed through the use of current injectors. Such injected fluxons are manipulated by means of homogeneous magnetic fields produced by microstrips carrying rectangular pulses. Low temperature microwave transmission characteristics show that such microstrips offer the possibility to control the barrier height of a vortex qubit on sub-nanosecond timescales.