Circuit Quantum Electrodynamics with Multimodal Photon-Qubit Coupling

Abstract

This thesis presents the results of experimental work aimed at realizing the multimodal Rabi Hamiltonian of quantum optics in a circuit QED device. We have fabricated and tested three coplanar waveguide resonators of fundamental frequency ω0/(2π) = 92 MHz, two of which contained superconducting transmon qubits. Both qubit devices failed to exhibit signs of light-matter coupling, as deduced through two different measurement techniques. The experimental progress was supplemented with numerical simulations of the multimodal Jaynes-Cummings and Rabi Hamiltonians, which attempted to study cavity-qubit dynamics in the multimodal regime for various light-matter coupling strengths. For a 2-mode Rabi model, we report the observation of a novel localization-delocalization transition in photon occupation between the two modes, which displays signatures that should be readily measured in experiment. Future work should continue attempts to realize strong, multimodal light-matter coupling in circuit QED so as to verify the existence of this transition.