Magnetic imaging of superconducting qubit devices with scanning SQUID-on-tip

TL;DR

This paper demonstrates the use of a scanning SQUID-on-tip to image magnetic flux in superconducting qubit devices, revealing current flow and flux trapping at nanometer scale, aiding in device optimization.

Contribution

It introduces a high-resolution magnetic imaging technique for superconducting qubits, providing detailed insights into current flow and flux trapping that were previously difficult to observe.

Findings

Nanometer-scale imaging of superconducting current flow.

Identification of flux trapping locations.

Insights into qubit control coupling mechanisms.

Abstract

We use a scanning superconducting quantum interference device (SQUID) to image the magnetic flux produced by a superconducting device designed for quantum computing. The nanometer-scale SQUID-on-tip probe reveals the flow of superconducting current through the circuit as well as the locations of trapped magnetic flux. In particular, maps of current flowing out of a flux-control line in the vicinity of a qubit show how these elements are coupled, providing insight on how to optimize qubit control.