Landau-Zener interferometry for qubits

One may probe coherence of a qubit by periodically sweeping its control parameter. The qubit is then excited by the Landau-Zener (LZ) mechanism. The interference between multiple LZ transitions leads to an oscillatory dependence of the energy absorption rate on the sweeping amplitude and on the period. This interference pattern allows to determine the decoherence time of the qubit. We introduce a simple phenomenological model describing this interferometer, and find the form of the interference pattern.Received: 21 October 2003, Published online: 8 December 2003PACS: 03.67.-a Quantum information - 85.25.Dq Superconducting quantum interference devicesD.A. Ivanov: Present address: Paul Scherrer Institute, 5232 Villigen PSI, Switzerland