标题： 三端口安德列夫自旋量子比特理论 显示英文标题

标题： Theory of three-terminal Andreev spin qubits

摘要： 在本文中，我们引入了一个简洁的理论框架，用于描述自旋-轨道相互作用系统中的平衡三端约瑟夫森效应，这一框架受到最近在InAs/Al异质结构上的实验[Phys. Rev. X 14, 031024 (2024)]的启发。我们开发了一个解析模型来捕捉系统的本质低能物理特性，并检验其作为安德列夫自旋量子比特的潜力，同时调和了参考文献[Phys. Rev. B 90, 155450 (2014)]中的一些发现。我们对结中安德列夫能级之间的跃迁进行了分析，结果表明，在理想化的情况下，最低的一对伪自旋分裂的安德列夫能级之间的跃迁被伪自旋守恒所阻止。我们证明，为了将系统用作安德列夫自旋量子比特，需要借助实验中观察到的显著自旋分裂，以及额外的要素，如外部磁场或磁性杂质。最后，我们将我们的模型应用于研究由超电流介导的两个此类量子比特之间的耦合。 显示英文摘要

摘要： In this paper, we introduce a concise theoretical framework for the equilibrium three-terminal Josephson effect in spin-orbit-interacting systems, inspired by recent experiments on an InAs/Al heterostructure [Phys. Rev. X 14, 031024 (2024)]. We develop an analytical model to capture the essential low-energy physics of the system and examine its potential as an Andreev spin qubit, while also reconciling some findings of Ref. [Phys. Rev. B 90, 155450 (2014)]. Our analysis of the transitions between the Andreev levels in the junction shows that, in an idealized scenario, the transition between the lowest pair of pseudo-spin-split Andreev levels is blocked by pseudo-spin conservation. We demonstrate that to operate the system as an Andreev spin qubit, leveraging the significant spin splitting observed experimentally, additional ingredients such as external magnetic filed or magnetic impurities are required. Finally, we apply our model to investigate the coupling between two such qubits, mediated by supercurrent.