论文标题
与自旋轨道相互作用的耦合超导旋转Qubit
Coupled superconducting spin qubits with spin-orbit interaction
论文作者
论文摘要
超导旋转Qubit，也称为Andreev旋转Qubt，有望结合量子点中定义的超导Qubits和自旋量子的好处。尽管大多数控制这些量子位的方法都依赖于通过超电流控制自旋度的自由度，但是超导旋转Qubits也可以通过超导体彼此耦合以实现两个Qubit的量子门。从理论上讲，我们研究了弱隧道方案中超导自旋矩之间的相互作用，并集中于自旋轨道相互作用（SOI）的效果，在基于半导体的量子点中可能很大，从而为量子门提供了附加的调谐参数。我们在分析上发现，两个超导旋转箭头之间的有效相互作用包括Ising，Heisenberg和Dzyaloshinskii-Moriya相互作用，并且可以通过超导相位差，隧道屏障强度或SOI参数来调节。约瑟夫森电流取决于SOI和旋转方向。我们证明，这种相互作用可用于以> 99.99％的忠诚度进行快速控制的相叉门。我们提出了一个可扩展的超导旋转Qubit的网络，该网络适用于实现表面代码。
Superconducting spin qubits, also known as Andreev spin qubits, promise to combine the benefits of superconducting qubits and spin qubits defined in quantum dots. While most approaches to control these qubits rely on controlling the spin degree of freedom via the supercurrent, superconducting spin qubits can also be coupled to each other via the superconductor to implement two-qubit quantum gates. We theoretically investigate the interaction between superconducting spin qubits in the weak tunneling regime and concentrate on the effect of spin-orbit interaction (SOI), which can be large in semiconductor-based quantum dots and thereby offers an additional tuning parameter for quantum gates. We find analytically that the effective interaction between two superconducting spin qubits consists of Ising, Heisenberg, and Dzyaloshinskii-Moriya interactions and can be tuned by the superconducting phase difference, the tunnel barrier strength, or the SOI parameters. The Josephson current becomes dependent on SOI and spin orientations. We demonstrate that this interaction can be used for fast controlled phase-flip gates with a fidelity >99.99%. We propose a scalable network of superconducting spin qubits which is suitable for implementing the surface code.
