1. A method of determining an operating parameter of a quantum information processing circuit, the method comprising: obtaining a linear response function of a quantum information processing circuit; generating a linear circuit model based on the linear response function; generating a composite circuit model based on combining the linear circuit model and a nonlinear circuit model, the nonlinear circuit model representing a nonlinear component in the quantum information processing circuit; and obtaining, by operation of one or more processors, an operating parameter of the quantum information processing circuit by solving the composite circuit model to include at least three quantum energy levels of the quantum information processing circuit.