Measurement of enhanced spin-orbit coupling strength for donor-bound electron spins in silicon

TL;DR

This paper demonstrates that the spin-orbit coupling strength for donor-bound electron spins in silicon can be significantly enhanced in multi-donor quantum dots, enabling potential all-electrical spin control.

Contribution

It reveals a method to locally enhance spin-orbit coupling in silicon donor systems, surpassing previous limitations and opening avenues for electrical spin manipulation.

Findings

Spin-orbit coupling is enhanced by over two orders of magnitude in multi-donor quantum dots.

Enhanced SOC reaches levels comparable to holes or certain two-donor systems.

Findings suggest potential for all-electrical control of donor spins in silicon.

Abstract

While traditionally considered a deleterious effect in quantum dot spin qubits, the spin-orbit interaction is recently being revisited as it allows for rapid coherent control by on-chip AC electric fields. For electrons in bulk silicon, SOC is intrinsically weak, however, it can be enhanced at surfaces and interfaces, or through atomic placement. Here we show that the strength of the spin-orbit coupling can be locally enhanced by more than two orders of magnitude in the manybody wave functions of multi-donor quantum dots compared to a single donor, reaching strengths so far only reported for holes or two-donor system with certain symmetry. Our findings may provide a pathway towards all-electrical control of donor-bound spins in silicon using electric dipole spin resonance (EDSR).