Europhys. Lett.
Volume 65, Number 6, March 2004
Page(s) 844 - 849
Section Interdisciplinary physics and related areas of science and technology
Published online 01 March 2004
Europhys. Lett., 65 (6) , pp. 844-849 (2004)
DOI: 10.1209/epl/i2003-10200-6

Observation of macroscopic Landau-Zener transitions in a superconducting device

A. Izmalkov1, 2, M. Grajcar1, 3, E. Il'ichev1, N. Oukhanski1, Th. Wagner1, H.-G. Meyer1, W. Krech4, M. H. S. Amin5, Alec Maassen van den Brink5 and A. M. Zagoskin5, 6

1  Institute for Physical High Technology - P.O. Box 100239, D-07702 Jena, Germany
2  Moscow Engineering Physics Institute (State University) Kashirskoe shosse 31, 115409 Moscow, Russia
3  Department of Solid State Physics, Comenius University SK-84248 Bratislava, Slovakia
4  Friedrich Schiller University, Institute of Solid State Physics D-07743 Jena, Germany
5  D-Wave Systems Inc. - 320-1985 West Broadway, Vancouver, B.C., V6J 4Y3 Canada
6  Physics and Astronomy Department, The University of British Columbia 6224 Agricultural Rd., Vancouver, B.C., V6T 1Z1 Canada

(Received 17 October 2003; accepted in final form 9 January 2004)

A two-level system traversing a level anticrossing has a small probability to make a so-called Landau-Zener (LZ) transition between its energy bands, in deviation from simple adiabatic evolution. This effect takes on renewed relevance due to the observation of quantum coherence in superconducting qubits (macroscopic "Schrödinger cat" devices). We report an observation of LZ transitions in an Al three-junction qubit coupled to a $\chem{Nb}$ resonant tank circuit.

85.25.Cp - Josephson devices.
85.25.Dq - Superconducting quantum interference devices (SQUIDs).
03.65.Ta - Foundations of quantum mechanics; measurement theory.

© EDP Sciences 2004