Quartet states in two-electron quantum dots in bilayer graphene
Quartet states in two-electron quantum dots in bilayer graphene
复制标题
DOI：
10.1103/physrevb.101.235423
复制
发表时间：
2020-06-12
影响因子：
3.7
通讯作者：
Fal'ko, Vladimir
中科院分区：
文献类型：
--
作者：
Knothe, Angelika;Fal'ko, Vladimir
将电子捕获到量子点中并控制其量子态对于将半导体结构转换为量子信息处理的比特至关重要。在这里，我们研究了带隙双层石墨烯(BLG)中静电诱导量子点中的单粒子态和两粒子态，其中电子的谷态与它们的自旋量子数成对出现。此外，BLG的电子结构特征，如每个山谷周围的三个小山谷，以及相应的轨道磁矩，都改变了点态的特征。在弱能隙情况下，单粒子能级方案是几乎二次带的方案。对于一个足够强的缺口，就会出现额外的三重“微谷退化”。基于这些单粒子态，我们分析了点中两个相互作用电子的轨道、自旋和谷态。我们发现自旋和谷单重态和三重态依赖于BLG和点参数，以及两粒子相互作用强度和外加磁场。单粒子态和两粒子态的多重性和自旋/谷态对于利用这些自由度进行量子输运和利用BLG量子点器件进行量子计算是必不可少的。
Trapping electrons in quantum dots and controlling their quantum states is crucial for converting semiconductor structures into bits of quantum information processing. Here, we study single- and two-particle states in electrostatically induced quantum dots in gapped bilayer graphene (BLG), where the electron's valley states appear in a pair with their spin quantum number. Moreover, the features of BLG's electronic structure, such as the three minivalleys around each valley, and the corresponding orbital magnetic moment, modify the characteristics of the dot states. In the weakly gapped case, the single-particle level scheme is that of an almost quadratic band. For a sufficiently strong gap, an additional threefold "minivalley degeneracy" emerges. Based on these single-particle states, we analyze the orbital, spin, and valley states of two interacting electrons in the dot. We find spin and valley singlets and triplet states depending on the BLG and dot parameters, as well as two-particle interaction strength and external magnetic field. The multiplicity and the spin/valley configuration of the single-and two-particle states are essential for using these degrees of freedom in quantum transport and quantum computing with BLG quantum dot devices.