Nonlinear mechanism of charge-qubit decoherence in a lossy cavity: Quasi-normal-mode approach
Yang Gao, Y. D. Wang, C. P. Sun · Physical Review A · 2005
From the viewpoint of quasinormal modes, we describe a decoherence mechanism of charge qubit of Josephson junctions (JJ) in a lossy microcavity, which can appear in a realistic experiment for quantum computation based on a JJ qubit. We show that nonlinear coupling of a charge qubit to the quantum cavity field can result in additional dissipation of the resonant mode due to the effective interaction between those nonresonant modes and the resonant mode, which is induced by the charge qubit itself. We calculate the characteristic time of the decoherence by making use of the system plus bath method.