Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa, 243-0198, Japan.
Nat Nanotechnol. 2014 Jul;9(7):505-8. doi: 10.1038/nnano.2014.129. Epub 2014 Jun 29.
Quantum dots are often called artificial atoms because, like real atoms, they confine electrons to quantized states with discrete energies. However, although real atoms are identical, most quantum dots comprise hundreds or thousands of atoms, with inevitable variations in size and shape and, consequently, unavoidable variability in their wavefunctions and energies. Electrostatic gates can be used to mitigate these variations by adjusting the electron energy levels, but the more ambitious goal of creating quantum dots with intrinsically digital fidelity by eliminating statistical variations in their size, shape and arrangement remains elusive. We used a scanning tunnelling microscope to create quantum dots with identical, deterministic sizes. By using the lattice of a reconstructed semiconductor surface to fix the position of each atom, we controlled the shape and location of the dots with effectively zero error. This allowed us to construct quantum dot molecules whose coupling has no intrinsic variation but could nonetheless be tuned with arbitrary precision over a wide range. Digital fidelity opens the door to quantum dot architectures free of intrinsic broadening-an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies of confined electrons.
量子点通常被称为人造原子，因为它们像真实原子一样，将电子限制在具有离散能量的量子态中。然而，尽管真实原子是相同的，但大多数量子点由数百或数千个原子组成，由于尺寸和形状不可避免的变化，因此它们的波函数和能量不可避免地存在差异。静电门可以通过调整电子能级来减轻这些变化，但通过消除其尺寸、形状和排列的统计变化来创建具有固有数字保真度的量子点的更雄心勃勃的目标仍然难以实现。我们使用扫描隧道显微镜创建了具有相同、确定尺寸的量子点。通过使用重构半导体表面的晶格来固定每个原子的位置，我们可以以有效的零误差控制点的形状和位置。这使我们能够构建量子点分子，其耦合没有内在的变化，但可以在很宽的范围内任意精确地进行调整。数字保真度为没有固有展宽的量子点架构打开了大门——这对于从纳米光子学到量子信息处理的技术以及对于受限电子的基础研究都是一个重要的目标。
