Dephasing of qubits by transverse low-frequency noise
Yu. Makhlin+,* and A. Shnirman+
+Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany
*L. D. Landau Institute for Theoretical Physics RAS, 117940 Moscow, Russia
PACS: 03.65.Yz, 75.10.Jm, 85.25.Cp
Abstract
We analyze the dissipative dynamics of a two-level quantum system
subject to low-frequency, e.g. 1/f noise, motivated by recent experiments
with superconducting quantum circuits. We show that the effect of transverse
linear coupling of the system to low-frequency noise is equivalent to that of
quadratic longitudinal coupling. We further find the decay law of quantum
coherent oscillations under the influence of both low- and high-frequency
fluctuations, in particular, for the case of comparable rates of relaxation
and pure dephasing.