Linear hyperfine tuning of donor spins in silicon using hydrostatic strain

TL;DR

This study demonstrates that donor spins in silicon can be linearly tuned by hydrostatic strain, enabling precise control for quantum technologies, with experimental and theoretical evidence showing significant strain-induced frequency shifts.

Contribution

The paper reveals a linear strain dependence of donor hyperfine interactions in silicon, contrasting previous quadratic models, and provides a quantitative framework for spin control in quantum devices.

Findings

Strain induces linear frequency shifts in donor spins, exceeding previous quadratic predictions.

Hydrostatic strain can shift donor electron spins by over a linewidth at strains of about 10^{-6}.

Strong spin-strain coupling up to 150 GHz per strain was observed for Bi donors in silicon.

Abstract

We experimentally study the coupling of Group V donor spins in silicon to mechanical strain, and measure strain-induced frequency shifts which are linear in strain, in contrast to the quadratic dependence predicted by the valley repopulation model (VRM), and therefore orders of magnitude greater than that predicted by the VRM for small strains $|\varepsilon| < 10^{-5}$. Through both tight-binding and first principles calculations we find that these shifts arise from a linear tuning of the donor hyperfine interaction term by the hydrostatic component of strain and achieve semi-quantitative agreement with the experimental values. Our results provide a framework for making quantitative predictions of donor spins in silicon nanostructures, such as those being used to develop silicon-based quantum processors and memories. The strong spin-strain coupling we measure (up to 150~GHz per strain, for Bi-donors in Si), offers a method for donor spin tuning --- shifting Bi donor electron spins by over a linewidth with a hydrostatic strain of order $10^{-6}$ --- as well as opportunities for coupling to mechanical resonators.