High-dynamic-range imaging of nanoscale magnetic fields using optimal control of a single qubit

TL;DR

This paper introduces a new quantum spectroscopy protocol that significantly enhances the dynamic range for nanoscale magnetic field imaging using a single NV center, enabling rapid, quantitative, and high-sensitivity magnetic field measurements.

Contribution

The authors develop a novel optimal control-based spectroscopy method that surpasses previous pulsed techniques in dynamic range for quantum sensing applications.

Findings

Achieves quantum-limited sensitivity with larger dynamic range.

Enables single-scan quantitative magnetic field imaging.

Operates without closed-loop control for inhomogeneous fields.

Abstract

We present a novel spectroscopy protocol based on optimal control of a single quantum system. It enables measurements with quantum-limited sensitivity (\eta_\omega ~ 1/sqrt(T_2^*),T_2^* denoting the system's coherence time) but has an orders of magnitude larger dynamic range than pulsed spectroscopy methods previously employed for this task. We employ this protocol to image nanoscale magnetic fields with a single scanning NV center in diamond. Here, our scheme enables quantitative imaging of a strongly inhomogeneous field in a single scan without closed-loop control, which has previously been necessary to achieve this goal.