Fast flux control of a high-Q 3D multimode cavity

Due to their long coherence times and ability to support strong superconducting-qubit-mediated interactions, 3D microwave cavities have established themselves as an excellent platform for circuit QED experiments. While magnetic fields serve as an important control knob for qubit frequencies and interactions in planar circuits, fast magnetic control of qubits in high-coherence 3D architectures is an outstanding challenge. The introduction of magnetic fields and flux bias lines without sharp reductions in quality factors and coherence times of the cavities requires careful engineering. In this talk, we present a design to introduce a fast flux bias line in high-Q 3D multimode systems without compromising on coherence. We also present a three-wave mixing scheme that uses RF flux pulses to swap photonic states between different cavities. Our results demonstrate a path to achieve fast control over long lived states in 3D microwave cavities using localized magnetic fields.