Scanning probe microscopy provides QCoR with unique capabilities to both fabricate and investigate quantum devices at the atomic scale, enabling direct connections between materials, microscopic defects, and qubit performance. Our efforts combine atomically precise manufacturing with nanoscale characterization techniques to advance device understanding and mitigate decoherence sources.

Atomically precise advanced manufacturing: We create semiconductor quantum devices with atomic precision using scanning tunneling microscopy in ultra-high vacuum. By patterning individual dopants with controlled spacing, we engineer quantum dots and coupled systems whose behavior can be directly compared with theory. Devices are fabricated through surface preparation and passivation, local depassivation with the STM tip, dopant incorporation, and epitaxial capping, followed by lithographic contacting and cryogenic measurement.

Two-level system characterization: We use scanning probe techniques to locate and study microscopic defects that act as two-level systems (TLS), a major source of qubit decoherence. Approaches include cryogenic scanning gate microscopy, where a biased tip perturbs an operating device to map TLS sensitivity, and sensor-on-tip methods that directly detect TLS signatures in materials, enabling defect identification and mitigation strategies.