Observation of macroscopic Landau-Zener transitions in a superconducting device

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

Corresponding author: ilichev@ipht-jena.de

Received: 17 October 2003
Accepted: 9 January 2004

Abstract

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 resonant tank circuit.