Variational tight-binding method for simulating large superconducting circuits

TL;DR

This paper introduces a variational tight-binding approach for efficiently simulating large superconducting circuits, outperforming traditional charge basis methods in accuracy and computational feasibility.

Contribution

It generalizes tight-binding techniques to superconducting circuits, enabling more efficient spectral analysis and simulation of larger systems.

Findings

Tight-binding states better approximate low-energy excitations than charge basis states.

The method significantly reduces Hilbert space size needed for accurate spectra.

Allows simulation of larger circuits previously infeasible with charge basis diagonalization.

Abstract

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