Fig. 3: Convergence of the Resolvent Method.
From: Renormalization and low-energy effective models in cavity and circuit quantum electrodynamics
Mean square error of the first 5 excited states with respect to the full model, as a function of the order of the resolvent expansion. The error decreases exponentially with the order of the series M, showing the convergence of the resolvent method. To make a comparison, we show also the QRM and RQRM errors. We used the same parameters as in Fig. 1c with g/ωc = 0.8.
