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Interplay of exchange and superexchange in triple quantum dots
Physical Review B ( IF 3.7 ) Pub Date : 
Kuangyin Deng, Edwin Barnes

Recent experiments on semiconductor quantum dots have demonstrated the ability to utilize a large quantum dot to mediate superexchange interactions and generate entanglement between distant spins. This opens up a possible mechanism for selectively coupling pairs of remote spins in a larger network of quantum dots. Taking advantage of this opportunity requires a deeper understanding of how to control superexchange interactions in these systems. Here, we consider a triple-dot system arranged in linear and triangular geometries. We use configuration interaction calculations to investigate the interplay of superexchange and nearest-neighbor exchange interactions as the location, detuning, and electron number of the mediating dot are varied. We show that superexchange processes strongly enhance and increase the range of the net spin-spin exchange as the dots approach a linear configuration. Furthermore, we show that the strength of the exchange interaction depends sensitively on the number of electrons in the mediator. Our results can be used as a guide to assist further experimental efforts towards scaling up to larger, two-dimensional quantum dot arrays.

中文翻译:

三重量子点中交换和超交换的相互作用

最近在半导体量子点上的实验证明了利用大量子点来介导超交换相互作用并在远距离自旋之间产生纠缠的能力。这为在较大的量子点网络中选择性地耦合成对的远程自旋开辟了一种可能的机制。抓住这个机会,需要对如何控制这些系统中的超交换交互有更深入的了解。在这里,我们考虑以线性和三角形几何形状排列的三点系统。我们使用构型相互作用计算来研究随着交换点的位置,失谐和电子数的变化,超级交换和最近邻交换相互作用的相互作用。我们显示,随着点趋于线性配置,超级交换过程会强烈增强和增加净自旋-自旋交换的范围。此外,我们表明交换相互作用的强度敏感地取决于介体中电子的数量。我们的结果可以用作指导,以协助进一步的实验工作,以扩大到更大的二维量子点阵列。
更新日期:2020-07-03
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