Controllable anisotropic exchange coupling between spin qubits in quantum dots

TL;DR

This paper proposes a method to control anisotropic exchange interactions in quantum dot spin qubits, enabling more versatile quantum gate operations by breaking symmetry with an external magnetic field.

Contribution

It introduces a novel approach to induce and control anisotropic interactions in quantum dot spin qubits using an external magnetic field, expanding quantum gate capabilities.

Findings

Achieved XXZ-type interactions in quantum dot systems.

Demonstrated efficient generation of GHZ states.

Linked quantum critical phenomena to communication capacity.

Abstract

The exchange coupling between quantum dot spin qubits is isotropic, which restricts the types of quantum gates that can be formed. Here, we propose a method for controlling anisotropic interactions between spins arranged in a bus geometry. The symmetry is broken by an external magnetic field, resulting in XXZ-type interactions that can efficiently generate Greenberger-Horne-Zeilinger (GHZ) states or universal gate sets for exchange-only quantum computing. Analysis of the bus ground state provides a link between quantum critical phenomena and the communication capacity.