Decoherence of qubits: results beyond Markovian approximation

In this paper the master equation method is used to calculate therelaxation and decoherence times of a qubit. The results are beyondMarkovian approximation, where the noise spectrum is assumed to bewide-band, so that they are valid for not only the wide- but alsothe narrow-band noises, which may be the main decoherence source insolid-state qubits. Moreover, for some special cases, analyticalresults can be achieved, which are consistent with those derived byothers.