Initial decoherence in solid state qubits

We study decoherence due to low frequency noise in Josephson qubits. Non-Markovian classical noise due to switching impurities determines inhomogeneous broadening of the signal. The theory is extended to include effects of high-frequency quantum noise, due to impurities or to the electromagnetic environment. The interplay of slow noise with intrinsically non-gaussian noise sources may explain the rich physics observed in the spectroscopy and in the dynamics of charge based devices.