Electrical control of the g-tensor of the first holein a silicon MOS quantum dot*

The spin state of a single hole in a semiconductor device provides a promising platform for a wide range of spin based quantum devices. A primary advantage of using holes, rather than electrons, is the intrinsically strong coupling of hole spins to electric fields. This strong spin-electric coupling allows rapid all-electrical control over the hole spin state, which is advantageous for many spin based devices, such as spin qubits [1-2]. However, due to the complexity of hole spin physics, gaps remain in our understanding of the mechanisms that enable electrical control of hole spins.

 

In this work, we report measurements and simulations of the g-tensor of a single hole that is confined in a silicon planar MOS quantum dot [3]. We show that thermal contraction of the metal gates in this MOS device produces a non-uniform strain profile, resulting in nanometre-scale variations in the hole-spin character. We show that local electric fields can be used to displace the hole relative to the non-uniform strain profile, therefore allowing a new mechanism for electric modulation of the hole g-tensor. Using this mechanism, we demonstrate tuning of the hole g-factor by up to 500%. In addition, we observe a potential sweet spot where dg_(110)/dV = 0, offering a possible configuration to suppress spin decoherence caused by electrical noise [4]. These results open a path towards a previously unexplored technology: engineering of non-uniform strains to optimise spin-based devices

 

[1] - Maurand, R., et al. Nature communications 7.1 (2016): 1-6.

[2] - Hendrickx, Nico W., et al. Nature 591.7851 (2021): 580-585.

[3] - Liles, S. D., et al. arXiv preprint arXiv:2012.04985 (2020).

[4] - Wang, Zhanning, et al. npj Quantum Information 7.1 (2021): 1-8