We calculate the spatial entanglement between two electrons trapped in a nanostructure for a broad class of confinement potentials, including single and double quantum dots, and core-shell quantum dot structures.
By using a parametrized confinement potential, we are able to switch from one structure to the others with continuity and to analyze how the entanglement is influenced by the changes in the confinement geometry. We calculate the many-body wave function by `exact' diagonalization of the time independent Schrödinger equation. We discuss the relationship between the entanglement and specific cuts of the wave function, and show that the wave function at a single highly symmetric point could be a good indicator for the entanglement content of the system. We analyze the counterintuitive relationship between spatial entanglement and Coulomb interaction, which connects maxima (minima) of the first to minima (maxima) of the latter. We introduce a potential quantum phase transition which relates quantum states characterized by different spatial topology. Finally we show that by varying shape, range and strength of the confinement potential, it is possible to induce strong and rapid variations of the entanglement between the two electrons. This property may be used to tailor nanostructures according to the level of entanglement required by a specific application.
Resonance fluorescence beyond the dipole approximation of a quantum dot in a plasmonic nanostructure
量子点（QD）的介观特性打破了偶极近似（DA），为光-物质相互作用的调控提供了新的维度[M. L. Andersen等人，7，215（2011）]。在这里，我们调查的功率谱和二阶相关性质的荧光从共振驱动量子点放置在一个平面金属。结果表明，由于量子点的空间延伸和金属附近的触发表面等离子体激元的剧烈变化，荧光有一个显着的贡献，从四极矩。在DA作用下，量子点取向荧光的π旋转对称性被破坏。通过控制量子点的取向和四极矩，可以使光谱在Mollow三重态和单峰之间切换，并且可以使以二阶关联函数中的反聚束为特征的荧光从弱辐射区变为强辐射区。我们的研究结果对于利用这种独特的介观效应来开发纳米光子器件具有指导意义。
Localized orbitals and tunnel couplings from general confinement potentials in gate-defined quantum-dot arrays
Institute for Quantum Computing and Department of Physics, University of Waterloo（滑铁卢大学量子计算研究所与物理系）；Institute for Quantum Computing and Department of Chemistry, University of Waterloo（滑铁卢大学量子计算研究所与化学系）
A circular dielectric grating for vertical extraction of single quantum dot emission
我们展示了一个纳米结构组成的部分蚀刻环形沟槽在悬浮的GaAs膜，设计用于有效和适度的宽带（约1000毫米）。5nm）的发射提取。模拟表明，嵌入纳米结构中心的偶极子以接近高斯的远场向上辐射到自由空间中，允许收集效率> 80%，具有高数值孔径（NA=0.7）光学器件，并且具有12 X Purcell辐射率增强。制造的器械显示出约10%的光子收集效率，NA=0.42物镜，比未图案化GaAs中的量子点提高20倍。四倍激子寿命减少表明适度的Purcell增强。
