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arXiv 1209.0920cond-mat.mes-hallquant-ph
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耦合InAs量子点中两个空穴或两个电子自旋相互作用的光学测量和模型化

Optical measurement and modeling of interactions between two hole or two electron spins in coupled InAs quantum dots

Alex Greilich, Ştefan C. Bădescu, Danny Kim, Allan S. Bracker, Daniel Gammon

摘要:

通过相干隧穿耦合的量子点中的两个电子自旋通常被认为近似服从海森堡各向同性交换。这还没有建立两个洞。在这里,我们测量光谱的两个空穴和两个电子在两个垂直堆叠的自组装InAs量子点使用光谱作为一个功能的电场和磁场。我们发现,这两个系统的交换是近似各向同性的,但显着的不对称贡献,所产生的自旋轨道和塞曼相互作用与空间不对称性相结合,需要解释大anticrossings和精细结构的能量分裂的光谱。非对称贡献的各向同性的哈密顿量的电子是百分之几的顺序,而空穴是一个数量级更大。

英文摘要:

Two electron spins in quantum dots coupled through coherent tunneling are generally acknowledged to approximately obey Heisenberg isotropic exchange. This has not been established for two holes. Here we measure the spectra of two holes and of two electrons in two vertically stacked self-assembled InAs quantum dots using optical spectroscopy as a function of electric and magnetic fields. We find that the exchange is approximately isotropic for both systems, but that significant asymmetric contributions, arising from spin-orbit and Zeeman interactions combined with spatial asymmetries, are required to explain large anticrossings and fine-structure energy splittings in the spectra. Asymmetric contributions to the isotropic Hamiltonian for electrons are of the order of a few percent while those for holes are an order of magnitude larger.

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