Optimal geometry of lateral GaAs and Si/SiGe quantum dots for electrical control of spin qubits

TL;DR

This paper explores how the orientation of magnetic fields and quantum dots affects the control and optimization of spin qubits in GaAs and Si/SiGe semiconductors, revealing strategies for improved qubit performance.

Contribution

It demonstrates how reorienting magnetic fields and quantum dots can optimize qubit control by leveraging spin-orbit interaction anisotropy, providing practical guidelines for device design.

Findings

Optimal qubit configurations depend on magnetic field and dot orientation.

Reorienting magnetic field alone can achieve optimal qubit conditions.

Dot geometry along [110] or [1$ar{1}$0] enhances robustness and control.

Abstract

We investigate the effects of the orientation of the magnetic field and the orientation of a quantum dot, with respect to crystallographic coordinates, on the quality of an electrically controlled qubit realized in a gated semiconductor quantum dot. We find that, due to the anisotropy of the spin-orbit interactions, varying the two orientations it is possible to tune the qubit in the sense of optimizing the ratio of its couplings to phonons and to a control electric field. We find conditions under which such optimal setup can be reached by solely reorienting the magnetic field, and when a specific positioning of the dot is required. We also find that the knowledge of the relative sign of the spin-orbit interactions strengths allows to choose a robust optimal dot geometry, with the dot main axis along [110], or [1$\overline{1}$0], where the qubit can be always optimized by reorienting the magnetic field.