# Extreme nuclear magnetic resonance: zero field, single spins, dark matter...

## TL;DR

This paper explores a novel low-field NMR regime dominated by J-coupling interactions, enabling new applications in spectroscopy, quantum control, and dark matter detection, especially when combined with single-spin quantum sensors.

## Contribution

It introduces the concept of extreme NMR at zero magnetic field and discusses its potential integration with single-spin sensors for advanced molecular spectroscopy.

## Key findings

- Low-field NMR dominated by J-coupling interactions.
- Potential for single-molecule J-spectroscopy.
- Applications in dark matter detection and quantum control.

## Abstract

An unusual regime for liquid-state nuclear magnetic resonance (NMR) where the magnetic field strength is so low that the $J$-coupling (intramolecular spin-spin) interactions dominate the spin Hamiltonian opens a new paradigm with applications in spectroscopy, quantum control, and in fundamental-physics experiments, including searches for well-motivated dark-matter candidates. An interesting possibility is to bring this kind of "extreme NMR" together with another one---single nuclear spin detected with a single-spin quantum sensor. This would enable single-molecule $J$-spectroscopy.