Qiao Haifeng, Kandel Yadav P, Fallahi Saeed, Gardner Geoffrey C, Manfra Michael J, Hu Xuedong, Nichol John M
Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA.
Phys Rev Lett. 2021 Jan 8;126(1):017701. doi: 10.1103/PhysRevLett.126.017701.
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.
由于其长的相干时间和可扩展性潜力，半导体量子点自旋量子比特在量子信息处理方面极具前景。然而，维持量子点自旋量子比特之间的高连通性（这有利于具有最近邻耦合的线性阵列）对大规模量子计算而言是一项挑战。在这项工作中，我们给出了关于半导体量子点中电子自旋量子比特之间长距离自旋链介导的超交换耦合的证据。我们将两个电子自旋弱耦合到一个两比特自旋链的两端。根据链的自旋状态，我们观察到远端自旋之间的振荡。我们解析了两端自旋以及链本身的动力学，并且我们的测量结果与模拟结果相符。超交换是一种在量子点自旋量子比特之间创建长距离耦合的有前景的技术。
