Power-law scaling of correlations in statistically polarised nano-NMR

Diffusion noise is a major source of spectral line broadening in liquid state nano-scale nuclear magnetic resonance with shallow nitrogen-vacancy centres, whose main consequence is a limited spectral resolution. This limitation arises by virtue of the widely accepted assumption that nuclear spin signal correlations decay exponentially in nano-NMR. However, a more accurate analysis of diffusion shows that correlations survive for a longer time due to a power-law scaling, yielding the possibility for improved resolution and altering our understanding of diffusion at the nano-scale. Nevertheless, such behaviour remains to be demonstrated in experiments. Using three different experimental setups and disparate measurement techniques, we present overwhelming evidence of power-law decay of correlations. These result in sharp-peaked spectral lines, for which diffusion broadening need not be a limitation to resolution.

Automated summary

Diffusion noise is the main cause of spectral line broadening in liquid-state nano-scale nuclear magnetic resonance with shallow nitrogen-vacancy centers, resulting in limited resolution. However, a more accurate analysis of diffusion reveals that correlations persist for a longer time at the nano-scale, allowing for improved resolution and challenging our understanding of diffusion. Through experiments using different setups and measurement techniques, we provide overwhelming evidence of power-law decay of correlations, leading to sharp-peaked spectral lines where diffusion broadening is no longer a limitation to resolution.