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

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 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 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.

Josephson and Persistent Currents in a Quantum Ring between Topological Superconductors

“…With this restriction, we lost some generality, but not the utility of the results, since some Aharonov–Bohm quantum‐rings architecture is based on InAs, for example, which could be used to prove the results. [ 53,54 ]…”

Josephson and persistent currents in a quantum ring between topological superconductors

“…We focus only on a system with N = 3 and N = 4 number of sites in the ring. With this restriction, we lost some generality, but not the utility of the results, since some Aharonov-Bohm quantum-rings architecture is based on InAs, for example, which could be used to prove the results [53,54].…”

Effects of Parity and Symmetry on the Aharonov–Bohm Phase of a Quantum Ring

“…The interior of the QD has no filled states due to the strong confinement, while electrons can still accumulate near the surface. 23 However, the resulting ring-like potential around the nanowire circumference is sensitive to perturbations, especially in a low carrier concentration limit, resulting in localized electron pockets. 26 The purpose of including two types of samples in this study, with a second sample having Sb in the InAs surface layer, is twofold, first to enhance the surface electron concentration as predicted from an Sb-induced conduction band bowing 27 and thereby screen effects of symmetry-breaking defects and second to further increase the spin–orbit interaction (SOI).…”

“…Nanowires were grown using metalorganic vapor-phase epitaxy from Au seeds arranged in periodic patterns, where the crystal structure of InAs was controlled as reported in ref ( 23 ). They were designed to have long outer contact segments with zinc blende (ZB) structure with a high carrier concentration.…”

“…We note that this value is larger than the corresponding value extracted in a similar structure consisting of InAs only. 23 This may be related to a non-negligible tail in the electron distribution that resides in the thin InAsSb shell 31 where SOI is strong.…”