Quantization of inductively-shunted superconducting circuits

Understand

We present a method for calculating the energy levels of superconducting circuits that contain highly anharmonic, inductively-shunted modes with arbitrarily strong coupling.

• Our method starts by calculating the normal modes of the linearized circuit and proceeds with numerical diagonalization in this basis.
• As an example, we analyze the Hamiltonian of a fluxonium qubit inductively coupled to a readout resonator.
• While elementary, this simple example is nontrivial because it cannot be efficiently treated by the method known as "black-box quantization," numerical diagonalization in the bare harmonic oscillator basis, or perturbation theory.