Spin-orbit coupling and intrinsic spin mixing in quantum dots

TL;DR

This paper investigates how spin-orbit coupling influences the electronic states in InSb quantum dots, revealing spin mixing, singlet-triplet transitions, and implications for quantum computing.

Contribution

It demonstrates the effects of competing Rashba and Dresselhaus interactions on quantum dot spectra and spin states, highlighting intrinsic spin flips and singlet-triplet mixing.

Findings

Spin-orbit coupling causes spin mixing in InSb quantum dots.

Singlet-triplet mixing affects the ground state and can be observed via FIR absorption.

Large negative g-factor leads to intrinsic spin flips at moderate magnetic fields.

Abstract

Spin-orbit coupling effects are studied in quantum dots in InSb, a narrow-gap material. Competition between different Rashba and Dresselhaus terms is shown to produce wholesale changes in the spectrum. The large (and negative) $g$-factor and the Rashba field produce states where spin is no longer a good quantum number and intrinsic flips occur at moderate magnetic fields. For dots with two electrons, a singlet-triplet mixing occurs in the ground state, with observable signatures in intraband FIR absorption, and possible importance in quantum computation.