Nanoscale magnetometry through quantum control of nitrogen-vacancy centres in rotationally diffusing nanodiamonds

TL;DR

This paper demonstrates how nitrogen-vacancy centers in rotationally diffusing nanodiamonds can be used for nanoscale magnetic sensing and biological imaging, leveraging quantum control and geometric phase accumulation.

Contribution

It develops quantum control methods for NV centers in freely rotating nanodiamonds, enabling real-time magnetic field sensing in biological environments.

Findings

Diffusing nanodiamonds can sense local magnetic fields.

Geometric phases influence quantum control in rotating nanodiamonds.

Nanodiamonds serve as both bio-labels and magnetometers.

Abstract

The confluence of quantum physics and biology is driving a new generation of quantum-based sensing and imaging technology capable of harnessing the power of quantum effects to provide tools to understand the fundamental processes of life. One of the most promising systems in this area is the nitrogen-vacancy centre in diamond - a natural spin qubit which remarkably has all the right attributes for nanoscale sensing in ambient biological conditions. Typically the nitrogen-vacancy qubits are fixed in tightly controlled/isolated experimental conditions. In this work quantum control principles of nitrogen-vacancy magnetometry are developed for a randomly diffusing diamond nanocrystal. We find that the accumulation of geometric phases, due to the rotation of the nanodiamond plays a crucial role in the application of a diffusing nanodiamond as a bio-label and magnetometer. Specifically, we show that a freely diffusing nanodiamond can offer real-time information about local magnetic fields and its own rotational behaviour, beyond continuous optically detected magnetic resonance monitoring, in parallel with operation as a fluorescent biomarker.