Spin dynamics of a solid-state qubit in proximity to a superconductor

TL;DR

This study investigates how a superconductor affects the spin coherence of a nearby nitrogen-vacancy center in diamond, revealing increased coherence times and enabling new imaging techniques for superconducting materials.

Contribution

It demonstrates that superconductors can enhance NV center spin coherence and introduces a novel imaging method based on relaxation times.

Findings

Superconductor proximity increases NV spin coherence lifetime.

Electric noise near NV centers is altered by superconducting charge redistribution.

Transverse relaxation time imaging reveals superconductor surface dynamics.

Abstract

A broad effort is underway to understand and harness the interaction between superconductors and spin-active color centers with an eye on the realization of hybrid quantum devices and novel imaging modalities of superconducting materials. Most work, however, overlooks the complex interplay between either system and the environment created by the color center host. Here we use an all-diamond scanning probe to investigate the spin dynamics of a single nitrogen-vacancy (NV) center proximal to a high-critical-temperature superconducting film in the presence of a weak magnetic field. We find that the presence of the superconductor increases the NV spin coherence lifetime, a phenomenon we tentatively rationalize as a change in the electric noise due to a superconductor-induced redistribution of charge carriers near the NV site. We build on these findings to demonstrate transverse-relaxation-time-weighted imaging of the superconductor film. These results shed light on the complex surface dynamics governing the spin coherence of shallow NVs while simultaneously paving the route to new forms of noise spectroscopy and imaging of superconductors.