Magnetic-field-induced delocalization in hybrid electron-nuclear spin ensembles

TL;DR

This paper demonstrates magnetic-field-dependent nuclear spin transport in diamond using RF techniques, revealing how electron spins mediate nuclear spin interactions and delocalization, with implications for quantum technologies.

Contribution

It introduces a theoretical framework and experimental evidence for magnetic-field-induced nuclear spin delocalization in hybrid electron-nuclear systems in diamond.

Findings

Magnetic-field controls nuclear spin transport in diamond.

RF absorption spectra show contributions from multi-spin sets.

Hybrid electron-nuclear interactions enable RF activity of zero-quantum transitions.

Abstract

We use field-cycling-assisted dynamic nuclear polarization and continuous radio-frequency (RF) driving over a broad spectral range to demonstrate magnetic-field-dependent activation of nuclear spin transport from strongly-hyperfine-coupled 13C sites in diamond. We interpret our observations with the help of a theoretical framework where nuclear spin interactions are mediated by electron spins. In particular, we build on the results from a 4-spin toy model to show how otherwise localized nuclear spins must thermalize as they are brought in contact with a larger ancilla spin network. Further, by probing the system response to a variable driving field amplitude, we witness stark changes in the RF-absorption spectrum, which we interpret as partly due to contributions from heterogeneous multi-spin sets, whose 'zero-quantum' transitions become RF active thanks to the hybrid electron-nuclear nature of the system. These findings could prove relevant in applications to dynamic nuclear polarization, spin-based quantum information processing, and nanoscale sensing.