Controlled coupling of spin-resolved quantum Hall edge states

TL;DR

This paper demonstrates a novel method to controllably couple spin-resolved quantum Hall edge states using a spatially-periodic magnetic field, achieving significant charge/spin transfer and advancing quantum information processing potential.

Contribution

It introduces an experimental technique employing nano-magnets to coherently couple spin-resolved edge states in a quantum Hall system, enabling scalable quantum information architectures.

Findings

Achieved up to 28% charge/spin transfer at 250 mK.

Demonstrated controllable coupling of co-propagating edge states.

Paved the way for spin-based topological quantum computing.

Abstract

Topologically-protected edge states are dissipationless conducting surface states immune to impurity scattering and geometrical defects that occur in electronic systems characterized by a bulk insulating gap. One example can be found in a two-dimensional electron gas (2DEG) under high magnetic field in the quantum Hall regime. Based on the coherent control of the coupling between these protected states, several theoretical proposals for the implementation of information processing architectures were proposed. Here we introduce and experimentally demonstrate a new method that allows us to controllably couple co-propagating spin-resolved edge states of a QH insulator. The scheme exploits a spatially-periodic in-plane magnetic field that is created by an array of Cobalt nano-magnets placed at the boundary of the 2DEG. A maximum charge/spin transfer of about 28% is achieved at 250 mK. This result may open the way to the realization of scalable quantum-information architectures exploiting the spin degree of freedom of topologically-protected states.