Dresden 2003 – scientific programme
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SYQI: Quantum information processing in condensed media
SYQI 3: Poster
SYQI 3.3: Poster
Wednesday, March 26, 2003, 14:30–19:00, P2d
Observation of quantum tunneling of a Josephson vortex — •Andreas Wallraff1, Jürgen Lisenfeld2, Alexandr Lukashenko2, Yuri Koval2, Misha Fistul2, and Alexey Ustinov2 — 1Department of Applied Physics / University of Yale, New Haven — 2Physikalisches Institut III / Universität Erlangen
We present first experimental observation of the macroscopic quantum tunneling of a single Josephson vortex through a magnetic-field controlled potential barrier in a long Josephson junction. The cross-over from thermal activation to quantum tunneling is observed in measurements of the vortex depinning current distribution when decreasing temperature. The quantized energy levels of the vortex in the well are observed spectroscopically by applying microwaves. The level separation scales with magnetic field and bias current as expected. The measured cross-over temperature is consistent with the theoretical prediction evaluated using the measured level separation. In the proposed vortex qubit two spatially distinct states of a quantum vortex in a double well potential can to be used to encode quantum information.