Progress on 3D qudit architecture with high-coherence SRF cavities

Superconducting radio frequency (SRF) cavities are excellent choices for storing quantum information as quantum d-level systems (qudits) due to their exceptionally long lifetimes and large accessible Hilbert spaces. A common strategy to manipulate the states is to use a nonlinear element like a transmon. There are however several challenges to build a 3D SRF architecture while maintaining a seconds long cavity lifetime. In this presentation, we demonstrate successful integration of superconducting qubits with a single-cell Nb SRF cavities. We discuss the experimental results with different approaches like photon-blockade and selective number dependent arbitrary phase gates to prepare non-classical states. Finally, we discuss our strategies to improve the coherence times and extend the system for building a multi-qudit quantum processor.