A scanning resonator for probing quantum coherent devices.

Area of Science:

• Quantum Computing and Solid State Physics
• Superconducting Quantum Circuits
• Advanced Materials Characterization

Background:

• Superconducting resonators are sensitive detectors for material impedance and qubit evolution in circuit quantum electrodynamics (circuit QED).
• Existing methods often require on-chip fabrication of resonators for each specific device under test.

Purpose of the Study:

• To implement a novel scanning resonator system for probing quantum coherent devices.
• To enable tunable coherent coupling to quantum systems without on-chip resonator fabrication.
• To characterize transmon qubits and material properties using a versatile, non-invasive technique.

Main Methods:

• Development of a scanning resonator system capable of tunable coherent coupling.
• Measurement of the resonator sensor's internal quality factor (>10^4) in the single-photon regime.
• Demonstration of capacitive imaging with zeptoFarad sensitivity and micron spatial resolution at milliKelvin temperatures.

Main Results:

• Achieved high internal quality factor for the resonator sensor, indicating excellent sensitivity.
• Successfully performed capacitive imaging, demonstrating sub-femtoFarad sensitivity and micron resolution.
• Characterized the energy spectrum and coherence times of transmon qubits without integrated readout circuitry.

Conclusions:

• The scanning resonator provides a new, flexible tool for quantum device characterization.
• This approach facilitates the study of existing and proposed qubit platforms using circuit QED principles.
• The system offers a pathway for non-invasive probing of quantum coherent devices and materials.