Composite-pulse magnetometry with a solid-state quantum sensor

TL;DR

This paper introduces a continuous driving composite pulse technique called rotary-echo for quantum magnetometry, enhancing sensitivity and robustness against control errors and decoherence, applicable to static and aperiodic fields.

Contribution

The authors demonstrate a novel composite-pulse magnetometry method using rotary-echo, improving robustness and flexibility in quantum sensing with solid-state sensors.

Findings

Achieved sensitivity in the microT/√Hz range

Extended coherence times approaching T1

Mitigated control errors and decoherence effects

Abstract

The sensitivity of quantum magnetometers is challenged by control errors and, especially in the solid-state, by their short coherence times. Refocusing techniques can overcome these limitations and improve the sensitivity to periodic fields, but they come at the cost of reduced bandwidth and cannot be applied to sense static (DC) or aperiodic fields. Here we experimentally demonstrate that continuous driving of the sensor spin by a composite pulse known as rotary-echo (RE) yields a flexible magnetometry scheme, mitigating both driving power imperfections and decoherence. A suitable choice of RE parameters compensates for different scenarios of noise strength and origin. The method can be applied to nanoscale sensing in variable environments or to realize noise spectroscopy. In a room-temperature implementation based on a single electronic spin in diamond, composite-pulse magnetometry provides a tunable trade-off between sensitivities in the microT/sqrt(Hz) range, comparable to those obtained with Ramsey spectroscopy, and coherence times approaching T1.