Optically detected NMR of optically hyperpolarized 31P neutral donors in 28Si

TL;DR

This paper demonstrates optically detected NMR of 31P donors in isotopically enriched silicon, enabling high-sensitivity nuclear spin measurements crucial for quantum computing applications.

Contribution

It introduces a novel optical hyperpolarization and readout technique for 31P nuclear spins in silicon, achieving single-shot NMR signals at low concentrations.

Findings

High signal-to-noise ratio NMR signals obtained optically.

Effective hyperpolarization of 31P nuclear spins at low magnetic fields.

Potential for quantum computing qubit readout applications.

Abstract

The electron and nuclear spins of the shallow donor 31P are promising qubit candidates invoked in many proposed Si-based quantum computing schemes. We have recently shown that the near-elimination of inhomogeneous broadening in highly isotopically enriched 28Si enables an optical readout of both the donor electron and nuclear spins by resolving the donor hyperfine splitting in the near-gap donor bound exciton transitions. We have also shown that pumping these same transitions can very quickly produce large electron and nuclear hyperpolarizations at low magnetic fields, where the equilibrium electron and nuclear polarizations are very small. Here we show preliminary results of the measurement of 31P neutral donor NMR parameters using this optical nuclear hyperpolarization mechanism for preparation of the 31P nuclear spin system, followed by optical readout of the resulting nuclear spin population after manipulation with NMR pulse sequences. This allows for the observation of single-shot NMR signals with very high signal to noise ratio under conditions where conventional NMR is not possible, due to the low concentration of 31P and the small equilibrium polarization.