Interacting Qubit-Photon Bound States with Superconducting Circuits

Understand

Qubits strongly coupled to a photonic crystal give rise to many exotic physical scenarios, beginning with single and multi-excitation qubit-photon dressed bound states comprising induced spatially localized photonic modes, centered around the qubits, and the qubits themselves.

• The localization of these states changes with qubit detuning from the band-edge, offering an avenue of in situ control of bound state interaction.
• Here, we present experimental results from a device with two qubits coupled to a superconducting microwave photonic crystal and realize tunable on-site and inter-bound state interactions.
• We observe a fourth-order two photon virtual process between bound states indicating strong coupling between the photonic crystal and qubits.