近日，荷兰代尔夫特理工大学的Christian Kraglund Andersen&Marta Pita-Vidal及其研究团队取得一项新进展。经过不懈努力，他们证实两个远距离超导自旋量子比特之间的强可调耦合。相关研究成果已于2024年5月6日在国际知名学术期刊《自然—物理学》上发表。

该研究团队成功证明了两个远距离Andreev自旋量子比特之间由强超电流介导的纵向耦合。他们进一步证实，这种耦合在强耦合状态下可通过门和磁通进行调节，并且磁通的应用能够原位关闭耦合。这一重要研究成果表明，将微观自旋态融入超导量子比特架构，不仅结合了半导体和超导电路的优势，更为实现远距离自旋间快速双量子比特门操作提供了可行的途径。

据悉，Andreev自旋量子比特最近作为一种替代的量子比特平台出现，并在半导体-超导混合纳米线中实现。在这些量子比特中，被约瑟夫森结捕获的准粒子的自旋自由度本质上是与结上的超电流耦合的自旋轨道。这种相互作用以前被用于执行自旋读出，但它也被预测为有利于感应多量子比特耦合。

附：英文原文

Title: Strong tunable coupling between two distant superconducting spin qubits

Author: Pita-Vidal, Marta, Wesdorp, Jaap J., Splitthoff, Lukas J., Bargerbos, Arno, Liu, Yu, Kouwenhoven, Leo P., Andersen, Christian Kraglund

Issue&Volume: 2024-05-06

Abstract: Andreev spin qubits have recently emerged as an alternative qubit platform with realizations in semiconductor–superconductor hybrid nanowires. In these qubits, the spin degree of freedom of a quasiparticle trapped in a Josephson junction is intrinsically spin–orbit coupled to the supercurrent across the junction. This interaction has previously been used to perform spin readout, but it has also been predicted to facilitate inductive multi-qubit coupling. Here we demonstrate a strong supercurrent-mediated longitudinal coupling between two distant Andreev spin qubits. We show that it is both gate- and flux-tunable into the strong coupling regime and, furthermore, that magnetic flux can be used to switch off the coupling in situ. Our results demonstrate that integrating microscopic spin states into a superconducting qubit architecture can combine the advantages of both semiconductors and superconducting circuits and pave the way to fast two-qubit gates between distant spins.

DOI: 10.1038/s41567-024-02497-x

Source: https://www.nature.com/articles/s41567-024-02497-x