The role of spin noise in the detection of nanoscale ensembles of nuclear spins

TL;DR

This paper demonstrates real-time observation of nuclear spin fluctuations at the nanoscale using magnetic resonance force microscopy, introducing a protocol to improve signal detection by controlling spin correlation and randomization.

Contribution

It presents a novel method to measure and control nuclear spin noise at the nanoscale, enhancing magnetic resonance imaging sensitivity.

Findings

Reproducible measurements of polarization variance achieved

Spin ensemble randomization improves signal-to-noise ratio

Real-time detection of nuclear spin fluctuations demonstrated

Abstract

When probing nuclear spins in materials on the nanometer scale, random fluctuations of the spin polarization will exceed the mean Boltzmann polarization for sample volumes below about (100nm)^3. In this work, we use magnetic resonance force microscopy to observe nuclear spin fluctuations in real time. We show how reproducible measurements of the polarization variance can be obtained by controlling the spin correlation time and rapidly sampling a large number of independent spin configurations. A protocol to periodically randomize the spin ensemble is demonstrated, allowing significant improvement in the signal-to-noise ratio for nanometer-scale magnetic resonance imaging.