Voltage tunability of single spin-states in a quantum dot

TL;DR

This paper demonstrates voltage-controlled tuning of spin energy levels in a single quantum dot, enabling potential universal electrical control of single spins for quantum information processing.

Contribution

It introduces voltage tunability of spin states in quantum dots, showing control over g-factors and spin eigenstates, advancing solid-state quantum manipulation techniques.

Findings

Discontinuous variation of electron in-plane g-factor with hole loading

Continuous variation of hole in-plane g-factor

Sign change in hole g-factor enabling avoided crossing

Abstract

Single spins in the solid-state offer a unique opportunity to store and manipulate quantum information, and to perform quantum-enhanced sensing of local fields and charges. Optical control of these systems using techniques developed in atomic physics has yet to exploit all the advantages of the solid-state. We demonstrate voltage tunability of the spin energy levels in a single quantum dot by modifying how spins sense magnetic field. We find the in-plane g-factor varies discontinuously for electrons, as more holes are loaded onto the dot. In contrast, the in-plane hole g-factor varies continuously. The device can change the sign of the in-plane g-factor of a single hole, at which point an avoided crossing is observed in the two spin eigenstates. This is exactly what is required for universal control of a single spin with a single electrical gate.