Variational tight-binding method for simulating large superconducting circuits

We generalize solid-state tight-binding techniques for the spectral analysis of large superconducting circuits. find that states can be better suited approximating low-energy excitations than charge basis states, as illustrated interesting example current-mirror circuit. The use tight binding dramatically lower Hilbert-space dimension required convergence to true spectrum, and allows accurate simulation larger circuits are out reach diagonalization.