Variational Perturbation Theory in Open Quantum Systems for Efficient Steady State Computation
This work introduces Variational Perturbation Theory (VPT) for open quantum systems to find steady states of devices like superconducting qubits. VPT improves upon standard perturbation theory by framing approximations as a low-dimensional variational problem, leading to a much wider convergence radius and better accuracy near critical points where standard methods fail. Two numerical strategies avoid costly pseudo-inverse calculations.