Building Qudit-Based Quantum Computing Architecture Using Superconducting Radio-Frequency Cavities

Abstract: 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 of these linear cavities is to use a nonlinear element like a transmon. There are however several challenges to building a 3D SRF architecture while maintaining a seconds-long cavity lifetime.

In this talk, we demonstrate the successful integration of superconducting qubits with single-cell Nb SRF cavities. We discuss the results obtained with different approaches like selective number-dependent arbitrary phase gates and echoed conditional displacement 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.