Long-Distance Superexchange between Semiconductor Quantum-Dot Electron Spins

TL;DR

This paper demonstrates long-distance superexchange coupling between semiconductor quantum-dot electron spins via a spin chain, addressing connectivity challenges in scalable quantum computing.

Contribution

It provides experimental evidence and analysis of superexchange coupling over long distances in quantum-dot spin qubits, a novel approach for scalable quantum architectures.

Findings

Observation of oscillations between distant spins mediated by a spin chain

Agreement of experimental results with theoretical simulations

Potential of superexchange for long-distance qubit coupling

Abstract

Because of their long coherence times and potential for scalability, semiconductor quantum-dot spin qubits hold great promise for quantum information processing. However, maintaining high connectivity between quantum-dot spin qubits, which favor linear arrays with nearest neighbor coupling, presents a challenge for large-scale quantum computing. In this work, we present evidence for long-distance spin-chain-mediated superexchange coupling between electron spin qubits in semiconductor quantum dots. We weakly couple two electron spins to the ends of a two-site spin chain. Depending on the spin state of the chain, we observe oscillations between the distant end spins. We resolve the dynamics of both the end spins and the chain itself, and our measurements agree with simulations. Superexchange is a promising technique to create long-distance coupling between quantum-dot spin qubits.