Tuning the Non-local Spin-Spin Interaction between Quantum Dots with a Magnetic Field

TL;DR

This paper presents a device that uses a small magnetic field to precisely control the magnitude and sign of the non-local spin-spin interaction between quantum dots mediated by 2DEGs, enabling tunable quantum coupling.

Contribution

It introduces a novel setup where magnetic fields tune the spin-spin interaction between quantum dots, including sign reversal and amplification, with potential for scalable quantum dot arrays.

Findings

Magnetic field can switch the sign of the spin-spin interaction.

Interaction strength is amplified when cyclotron radius matches interdot distance.

Multiple dots can be coupled linearly beyond nearest neighbors.

Abstract

We describe a device where the non-local spin-spin interaction between two quantum dots can be turned on and off and even changed sign with a very small magnetic field. The setup consists of two quantum dots at the edge of two two-dimensional electron gases (2DEGs). The quantum dots' spins are coupled through a RKKY-like interaction mediated by the electrons in the 2DEGs. A small magnetic field perpendicular to the plane of the 2DEG is used as a tuning parameter. When the cyclotron radius is commensurate with the interdot distance, the spin-spin interaction is amplified by a few orders of magnitude. The sign of the interaction is controlled by finely tuning the magnetic field. Our setup allows for several dots to be coupled in a linear arrangement and it is not restricted to nearest-neighbors interaction.