论文标题
半导体量子中二维孔气体的强可调线性Rashba自旋轨道耦合的出现
Emergence of the strong tunable linear Rashba spin-orbit coupling of two-dimensional hole gases in semiconductor quantum
论文作者
论文摘要
半导体量子孔中的二维孔气体是用于旋转和量子计算的有前途的平台，但由于缺乏$ \ bf {k} $ - 在Rashba旋转轨道耦合（SOC）中的线性术语（SOC），这对于无磁性的旋转操作和通常是bel的旋转操作至关重要的是$ \ bf-bf-bf-bf-bf-bf-bf-bf cub-bf- k} cubf-bf {在这里，与传统的智慧相反，我们通过执行有效的hamiltonian的ge/si量子量量子系统结合了GE/SI量子系统，从而发现了半导体量子孔的二维孔气（2DHG），以二维孔气体（2DHG）的形式揭示了一个强大而可调的$ \ bf {k} $ - 线性rashba Soc。它的最大强度超过120mEVå，与狭窄的带隙III-V半导体2D电子气体中报告的最高值相当，由于存在核自旋而导致的自旋寿命短。我们还说明，这种新兴的$ \ bf {k} $ - 线性Rashba Soc是一阶直接Rashba效应，源自重孔 - 阳光孔混合和直接偶极偶极间悬挂式耦合到外部电场的组合。这些发现证实基于GE的2DHG是迈向大规模量子计算的绝佳平台。
Two-dimensional hole gases in semiconductor quantum wells are promising platforms for spintronics and quantum computation but suffer from the lack of the $\bf{k}$-linear term in the Rashba spin-orbit coupling (SOC), which is essential for spin manipulations without magnetism and commonly believed to be a $\bf{k}$-cubic term as the lowest order. Here, contrary to conventional wisdom, we uncover a strong and tunable $\bf{k}$-linear Rashba SOC in two-dimensional hole gases (2DHG) of semiconductor quantum wells by performing atomistic pseudopotential calculations combined with an effective Hamiltonian for a model system of Ge/Si quantum wells. Its maximal strength exceeds 120 meVÅ, comparable to the highest values reported in narrow bandgap III-V semiconductor 2D electron gases, which suffers from short spin lifetime due to the presence of nuclear spin. We also illustrate that this emergent $\bf{k}$-linear Rashba SOC is a first-order direct Rashba effect, originating from a combination of heavy-hole-light-hole mixing and direct dipolar intersubband coupling to the external electric field. These findings confirm Ge-based 2DHG to be an excellent platform towards large-scale quantum computation.
