Decoherence of a qubit by non-Gaussian noise at an arbitrary working point

J. Bergli,1,2,* Y. M. Galperin,1,3,4 and B. L. Altshuler2 1Department of Physics and Center for Advanced Materials and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway 2Physics Department, Princeton University, Princeton, New Jersey 08544, USA 3Argonne National Laboratory, 9700 S. Cass Ave., Argonne, Illinois 60439, USA 4A. F. Ioffe Physico-Technical Institute of Russian Academy of Sciences, 194021 St. Petersburg, Russia Received 22 March 2006; revised manuscript received 1 June 2006; published 14 July 2006