Europhys. Lett.
Volume 71, Number 1, July 2005
Page(s) 21 - 27
Section General
Published online 27 May 2005
Europhys. Lett., 71 (1), pp. 21-27 (2005)
DOI: 10.1209/epl/i2005-10053-y

Rabi oscillations of a qubit coupled to a two-level system

Y. M. Galperin1, 2, 3, D. V. Shantsev1, 2, J. Bergli4 and B. L. Altshuler4, 5

1  Department of Physics, University of Oslo PO Box 1048 Blindern, 0316 Oslo, Norway
2  A. F. Ioffe Physico-Technical Institute of Russian Academy of Sciences 194021 St. Petersburg, Russia
3  Argonne National Laboratory - 9700 S. Cass av., Argonne, IL 60439, USA
4  Physics Department, Princeton University - Princeton, NJ 08544, USA
5  NEC-Laboratories America, Inc. - 4 Independence Way, Princeton, NJ 08540, USA

received 27 April 2005; accepted 29 April 2005
published online 27 May 2005

The problem of Rabi oscillations in a qubit coupled to a fluctuator and in contact with a heath bath is considered. A scheme is developed for taking into account both phase and energy relaxation in a phenomenological way, while taking full account of the quantum dynamics of the four-level system subject to a driving AC field. Significant suppression of the Rabi oscillations is found when the qubit and fluctuator are close to resonance. The effect of the fluctuator state on the read-out signal is discussed. This effect is shown to modify the observed signal significantly. This may be relevant to recent experiments by Simmonds et al. (Phys. Rev. Lett. 93 (2004) 077003).

03.65.Yz - Decoherence; open systems; quantum statistical methods.
03.67.Lx - Quantum computation.
85.25.Cp - Josephson devices.

© EDP Sciences 2005