Simultaneous sub-second hyperpolarization of the nuclear and electron spins of phosphorus in silicon

TL;DR

This paper presents a rapid method to hyperpolarize both electron and nuclear spins of phosphorus donors in silicon at low magnetic fields, achieving high polarization levels in under a second, facilitating quantum computing and spin studies.

Contribution

The authors introduce a novel optical pumping technique that simultaneously hyperpolarizes electron and nuclear spins of 31P in silicon at low fields, which was not previously achievable in such a short timescale.

Findings

Achieved 90% electron spin polarization in less than a second.

Achieved 76% nuclear spin polarization in less than a second.

Enabled efficient initialization for qubits and advanced ESR/NMR studies.

Abstract

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.