Resolving the positions of defects in superconducting quantum bits

Area of Science:

• Quantum Computing
• Solid-State Physics
• Materials Science

Background:

• Superconducting circuits are advancing rapidly, enabling prototype quantum processors.
• Material defects are a primary source of decoherence and energy loss in quantum devices.
• The structure and origin of these defects remain poorly understood.

Purpose of the Study:

• To develop a technique for locating defects within qubit circuits.
• To understand the spatial distribution of defects relative to device interfaces.
• To provide insights for improving material quality and fabrication processes.

Main Methods:

• Tuning defect resonance frequencies using electric fields from surrounding electrodes.
• Measuring defect coupling strength to individual electrodes.
• Comparing experimental coupling data with simulated electric field distributions.

Main Results:

• Successfully determined the probability of defect locations at specific interfaces within the qubit circuit.
• Provided a method applicable to existing quantum device samples without modification.
• Enabled precise defect localization relative to the thin film edge.

Conclusions:

• The developed technique offers a valuable tool for enhancing quantum circuit coherence.
• Understanding defect locations is crucial for improving material quality and nanofabrication.
• This method facilitates the advancement of more robust solid-state quantum coherent devices.