Abstract: Advancing qubits and other quantum-coherent devices requires sensitive and efficient probes operating in the single-quantum regime. High-quality superconducting resonators have proven to be effective detectors of single-quantum excitations and coherence properties across multiple device systems through circuit quantum electrodynamics (circuit QED) interactions. However, conventional implementations with resonators fixed on the sample chip often suffer from reduced sensitivity on lossy materials and limited spatial resolution, restricting their use in emerging quantum hardware platforms where energy relaxation and mesoscopic inhomogeneity hinder precise engineering of quantum states. In this presentation, I will introduce a newly developed scanning resonator probe that overcomes these limitations. The resonators, fabricated on a dedicated probe chip, maintain high quality factors down to the few-photon regime for sensitive circuit QED measurements. Our scanning platform enables precise in situ control of probe–sample coupling and efficient spatial imaging of device properties. Using this setup, we characterized the energy spectra and coherence times of multiple transmon qubits without any on-chip readout circuitry. I will conclude with perspectives on using scanning resonators to investigate mesoscopic decoherence sources in existing solid-state qubits and to explore emerging materials systems for next-generation quantum hardware.
Bio: Zhanzhi is a postdoc working for Professor Angela Kou researching solid-state qubits and quantum materials using scanning resonators.