Multiphoton Processes in a Quasi-1D Coplanar Waveguide Array

Circuit quantum electrodynamics (circuit QED) is one of the leading platforms for quantum computing and quantum simulation with the strong qubit-photon coupling native to the platform. Coplanar waveguide resonator (CPW) lattices with periodic arrays of localized sites are effective photonic crystals in the microwave regime and allow for the engineering of band structure with unconventional features like linear band crossings and flat bands. In this talk, we will present measurements of multi-photon processes in a quasi-1D CPW lattice with transmon qubits. We demonstrate the existence of four-wave mixing resonances between the qubits and normal modes of the lattice, and show that Kerr non-linearities can be harnessed to diagnose in-situ coupling strengths, and the unconventional band structure presented in our device.