Potts H, Chen I-J, Tsintzis A, Nilsson M, Lehmann S, Dick K A, Leijnse M, Thelander C
Division of Solid State Physics and NanoLund, Lund University, SE-221 00, Lund, Sweden.
Centre for Analysis and Synthesis, Lund University, SE-221 00, Lund, Sweden.
Nat Commun. 2019 Dec 16;10(1):5740. doi: 10.1038/s41467-019-13583-7.
Emerging theoretical concepts for quantum technologies have driven a continuous search for structures where a quantum state, such as spin, can be manipulated efficiently. Central to many concepts is the ability to control a system by electric and magnetic fields, relying on strong spin-orbit interaction and a large g-factor. Here, we present a mechanism for spin and orbital manipulation using small electric and magnetic fields. By hybridizing specific quantum dot states at two points inside InAs nanowires, nearly perfect quantum rings form. Large and highly anisotropic effective g-factors are observed, explained by a strong orbital contribution. Importantly, we find that the orbital contributions can be efficiently quenched by simply detuning the individual quantum dot levels with an electric field. In this way, we demonstrate not only control of the effective g-factor from 80 to almost 0 for the same charge state, but also electrostatic change of the ground state spin.
量子技术中新兴的理论概念推动了对能够有效操纵量子态（如自旋）的结构的持续探索。许多概念的核心是依靠强自旋轨道相互作用和大g因子，通过电场和磁场来控制系统的能力。在此，我们提出了一种利用小电场和小磁场进行自旋和轨道操纵的机制。通过在InAs纳米线内部的两个点处混合特定的量子点态，形成了近乎完美的量子环。观察到了大的且高度各向异性的有效g因子，这可由强轨道贡献来解释。重要的是，我们发现通过简单地用电场失谐各个量子点能级，轨道贡献可以被有效地淬灭。通过这种方式，我们不仅证明了对于相同电荷态，有效g因子可从80控制到几乎为0，还展示了基态自旋的静电变化。
