Electrical control of spins and giant g-factors in ring-like coupled quantum dots

TL;DR

This paper demonstrates a novel method to control spin states and g-factors in quantum rings formed by hybridized quantum dot states in InAs nanowires using electric and magnetic fields, enabling efficient quantum state manipulation.

Contribution

It introduces a new mechanism for spin and orbital control in quantum rings through hybridization and electric field tuning, with significant g-factor modulation.

Findings

Large, anisotropic g-factors observed due to orbital effects

Electric fields can quench orbital and spin-orbital contributions

G-factor can be tuned from 80 to nearly 0 within the same charge state

Abstract

Emerging theoretical concepts for quantum technologies have driven a continuous search for structures where a quantum state, such as spin, can be manipulated efficiently. Central to many concepts is the ability to control a system by electric and magnetic fields, relying on strong spin-orbit interaction and a large g-factor. Here, we present a new mechanism for spin and orbital manipulation using small electric and magnetic fields. By hybridizing specific quantum dot states at two points inside InAs nanowires, nearly perfect quantum rings form. Large and highly anisotropic effective g-factors are observed, explained by a strong orbital contribution. Importantly, we find that the orbital and spin-orbital contributions can be efficiently quenched by simply detuning the individual quantum dot levels with an electric field. In this way, we demonstrate not only control of the effective g-factor from 80 to almost 0 for the same charge state, but also electrostatic change of the ground state spin.