Readout of fluxonium qubits in circuit QED

In the idealized dispersive model of circuit QED, a single-shot heterodyne qubit measurement can be made as accurate as desired by increasing the power of the microwave drive. However, in realistic systems, populating the microwave cavity with photons can have many detrimental effects: in addition to nonlinear effects in the cavity itself, its photons can increase qubit relaxation and excitation rates, including excitations to noncomputational states. In addition, a high drive power can induce resonance transitions between qubit states. In this talk, we present the results of the simulation of the readout process in the fluxonium circuit and discuss how the qubit states and integrated readout signal are affected by the cavity occupation.