Conditional control of donor nuclear spins in silicon using Stark shifts

TL;DR

This paper demonstrates electric-field-based conditional control of donor nuclear spins in silicon using Stark shifts, achieving high-fidelity operations through innovative techniques and strategies to mitigate inhomogeneities.

Contribution

It introduces methods to conditionally control donor nuclear spins in silicon via Stark shifts, including a dynamic decoupling technique and strategies for high-fidelity operations.

Findings

Achieved above 90% process fidelity in nuclear spin control.

Demonstrated electric-field induced conditional phase gate.

Showed effective detuning of spins off-resonance.

Abstract

Electric fields can be used to tune donor spins in silicon using the Stark shift, whereby the donor electron wave function is displaced by an electric field, modifying the hyperfine coupling between the electron spin and the donor nuclear spin. We present a technique based on dynamic decoupling of the electron spin to accurately determine the Stark shift, and illustrate this using antimony donors in isotopically purified silicon-28. We then demonstrate two different methods to use a DC electric field combined with an applied resonant radio-frequency (RF) field to conditionally control donor nuclear spins. The first method combines an electric-field induced conditional phase gate with standard RF pulses, and the second one simply detunes the spins off-resonance. Finally, we consider different strategies to reduce the effect of electric field inhomogeneities and obtain above 90% process fidelities.