Angstrom-resolution magnetic resonance imaging of single molecules via wavefunction fingerprints of nuclear spins

TL;DR

This paper introduces a wave-function fingerprinting method for nuclear spins that surpasses frequency-based techniques, enabling angstrom-resolution MRI of single molecules and localizing nuclear spins with unprecedented precision.

Contribution

The authors develop a novel wave-function fingerprinting approach that overcomes frequency fingerprint limitations, achieving angstrom-scale resolution in single-molecule MRI.

Findings

Demonstrated angstrom-resolution MRI scheme for single nuclear spins

Able to count and localize nuclear spins with the same frequency

Characterized correlations in nuclear-spin clusters

Abstract

Single-molecule sensitivity of nuclear magnetic resonance (NMR) and angstrom resolution of magnetic resonance imaging (MRI) are the highest challenges in magnetic microscopy. Recent development in dynamical-decoupling- (DD) enhanced diamond quantum sensing has enabled single-nucleus NMR and nanoscale NMR. Similar to conventional NMR and MRI, current DD-based quantum sensing utilizes the frequency fingerprints of target nuclear spins. The frequency fingerprints by their nature cannot resolve different nuclear spins that have the same noise frequency or differentiate different types of correlations in nuclear-spin clusters, which limit the resolution of single-molecule MRI. Here we show that this limitation can be overcome by using wave-function fingerprints of target nuclear spins, which is much more sensitive than the frequency fingerprints to the weak hyperfine interaction between the targets and a sensor under resonant DD control. We demonstrate a scheme of angstrom-resolution MRI that is capable of counting and individually localizing single nuclear spins of the same frequency and characterizing the correlations in nuclear-spin clusters. A nitrogen-vacancy-center spin sensor near a diamond surface, provided that the coherence time is improved by surface engineering in the near future, may be employed to determine with angstrom resolution the positions and conformation of single molecules that are isotope labeled. The scheme in this work offers an approach to breaking the resolution limit set by the frequency gradients in conventional MRI and to reaching the angstrom-scale resolution.