In-situ scanning gate imaging of individual two-level material defects in live superconducting quantum circuits

TL;DR

This paper introduces a scanning gate microscopy technique to locate and analyze individual two-level system defects in superconducting quantum circuits at millikelvin temperatures, providing insights into their microscopic nature and orientation.

Contribution

It presents a novel in-situ imaging method for identifying and characterizing individual TLS in live quantum circuits, advancing understanding of their microscopic origins.

Findings

Successfully locates individual TLS in superconducting circuits.

Determines the three-dimensional orientation of TLS electric dipoles.

Provides insights into the microscopic and chemical nature of TLS.

Abstract

The low temperature physics of structurally amorphous materials is governed by two-level system defects (TLS), the exact origin and nature of which remain elusive despite decades of study. Recent advances towards realising stable high-coherence platforms for quantum computing has increased the importance of studying TLS in solid-state quantum circuits, as they are a persistent source of decoherence and instability. Here we perform scanning gate microscopy on a live superconducting quantum circuit at millikelvin temperatures to locate individual TLS. Our method directly reveals the microscopic nature of TLS and is also capable of deducing the three dimensional orientation of individual TLS electric dipole moments. Such insights, when combined with structural information of the underlying materials, can help unravel the detailed microscopic nature and chemical origin of TLS, directing strategies for their eventual mitigation.