Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands.
Nature. 2010 Dec 23;468(7327):1084-7. doi: 10.1038/nature09682.
Motion of electrons can influence their spins through a fundamental effect called spin-orbit interaction. This interaction provides a way to control spins electrically and thus lies at the foundation of spintronics. Even at the level of single electrons, the spin-orbit interaction has proven promising for coherent spin rotations. Here we implement a spin-orbit quantum bit (qubit) in an indium arsenide nanowire, where the spin-orbit interaction is so strong that spin and motion can no longer be separated. In this regime, we realize fast qubit rotations and universal single-qubit control using only electric fields; the qubits are hosted in single-electron quantum dots that are individually addressable. We enhance coherence by dynamically decoupling the qubits from the environment. Nanowires offer various advantages for quantum computing: they can serve as one-dimensional templates for scalable qubit registers, and it is possible to vary the material even during wire growth. Such flexibility can be used to design wires with suppressed decoherence and to push semiconductor qubit fidelities towards error correction levels. Furthermore, electrical dots can be integrated with optical dots in p-n junction nanowires. The coherence times achieved here are sufficient for the conversion of an electronic qubit into a photon, which can serve as a flying qubit for long-distance quantum communication.
电子的运动可以通过一种称为自旋轨道相互作用的基本效应影响其自旋。这种相互作用提供了一种电控制自旋的方法，因此是自旋电子学的基础。即使在单个电子的水平上，自旋轨道相互作用也已被证明在相干自旋旋转方面很有前景。在这里，我们在砷化铟纳米线中实现了自旋轨道量子位（qubit），其中自旋轨道相互作用非常强，以至于自旋和运动不再可以分开。在这种情况下，我们仅使用电场实现了快速的量子比特旋转和通用的单量子比特控制；qubit 位于单个电子量子点中，这些量子点可以单独寻址。我们通过动态地将量子比特与环境解耦来增强相干性。纳米线为量子计算提供了多种优势：它们可以作为可扩展量子比特寄存器的一维模板，甚至可以在导线生长过程中改变材料。这种灵活性可用于设计具有抑制退相干的导线，并将半导体量子比特保真度推向纠错水平。此外，电点可以与 p-n 结纳米线中的光点集成。这里达到的相干时间足以将电子量子比特转换为光子，这可以作为长距离量子通信的飞行量子比特。
