Modeling of quasiparticle-induced excitations of a Josephson   charge-phase qubit
  We have analyzed quasiparticle transitions in an Al charge-phase qubit inducing a dynamic change of the qubit states. The time-averaged mixed state is related to the strong coupling of the qubit to an ensemble of non-equilibrium quasiparticles in the leads. Such quasiparticles tunnel stochastically on and off the island and can excite the qubit. Continuous monitoring of the qubit impedance at a frequency of 80 MHz shows the admixture of the excited state. We present a numerical description of these cyclic transitions and compare it with our experimental data. 
J. K\"onemann, H. Zangerle, B. Egeling, R. Harke, B. Mackrodt, R.   Dolata, and A. B. Zorin