Drive-induced lifetime renormalization of superconducting qubits II: The Readout Problem

Recent experiments found a strong dependence of qubit relaxation rates on the readout drive power. The observed dynamics can not be fully explained by previous theoretical approaches based on the Jaynes-Cummings, Rabi or Kerr based models. We show that an effective master equation that accounts for renormalization of dissipative parameters due to number non-conserving terms inherent in the Josephson nonlinearity captures with good qualitative agreement this strong dependence. We account for a realistic experimental setting with a finite bath temperature and an additional pure dephasing channel, both of which are shown to significantly enhance the qubit relaxation renormalization with drive. Effective master equations for driven Josephson circuits appear to provide an accurate and computationally resource-efficient approach to experimentally relevant settings.