Strong spin-orbit interaction and g-factor renormalization of hole spins in Ge/Si nanowire quantum dots
Strong spin-orbit interaction and g-factor renormalization of hole spins in Ge/Si nanowire quantum dots
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DOI：
10.1103/physrevresearch.3.013081
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发表时间：
2021-01-26
影响因子：
4.2
通讯作者：
Braakman, F. R.
中科院分区：
文献类型：
--
作者：
Froning, F. N. M.;Rancic, M. J.;Braakman, F. R.
自旋轨道相互作用是自旋量子比特量子计算、拓扑非平凡态研究和自旋电子学各种应用的核心。Ge/Si核/壳纳米线中的空穴自旋经历了一种自旋轨道相互作用，这种相互作用被预测为既强又电可调，使它们成为这些领域研究的一个特别有前途的平台。我们通过测量自旋混合跃迁在自旋阻塞输运的范围内，实验确定了锗/硅纳米线中双量子点的空穴自旋的自旋轨道相互作用强度。我们发现了一个非常短的自旋轨道长度，大约为65 nm，与量子点长度和点间距离相当。我们还观察到外加磁场对空穴态有很大的轨道效应，导致自旋混合跃迁能对磁场有很大的依赖性。引人注目的是，与这些轨道效应一起，强自旋轨道相互作用导致g因子随磁场的显著增强。所证明的大自旋轨道相互作用强度与该材料体系中预测的直接Rashba自旋轨道相互作用一致，有望实现自旋量子比特的超快Rabi振荡和有效的量子比特-量子比特相互作用，并为研究Majorana零模式提供合适的平台。
The spin-orbit interaction lies at the heart of quantum computation with spin qubits, research on topologically nontrivial states, and various applications in spintronics. Hole spins in Ge/Si core/shell nanowires experience a spin-orbit interaction that has been predicted to be both strong and electrically tunable, making them a particularly promising platform for research in these fields. We experimentally determine the strength of spin-orbit interaction of hole spins confined to a double quantum dot in a Ge/Si nanowire by measuring spin-mixing transitions inside a regime of spin-blockaded transport. We find a remarkably short spin-orbit length of similar to 65 nm, comparable to the quantum dot length and the interdot distance. We additionally observe a large orbital effect of the applied magnetic field on the hole states, resulting in a large magnetic field dependence of the spin-mixing transition energies. Strikingly, together with these orbital effects, the strong spin-orbit interaction causes a significant enhancement of the g factor with magnetic field. The large spin-orbit interaction strength demonstrated is consistent with the predicted direct Rashba spin-orbit interaction in this material system and is expected to enable ultrafast Rabi oscillations of spin qubits and efficient qubit-qubit interactions, as well as provide a platform suitable for studying Majorana zero modes.