论文标题
Aharonov-bohm笼子,平坦的带和间隙标记在双曲线砖中
Aharonov-Bohm cages, flat bands, and gap labeling in hyperbolic tilings
论文作者
论文摘要
Aharonov-bohm笼子是由几何和磁场之间的竞争造成的定位机制。这种破坏性的干扰现象最初是针对骰子晶格中的紧密结合模型所描述的,可防止任何波袋从严格的密闭区域散开。因此,对于负责此效果的磁场的特殊值,能量谱由一组离散的高度退化平坦带组成。在目前的工作中,我们表明在一个无限的双曲骰子砖中也发现了Aharonov-bohm笼子,该骰子块在负弯曲的双曲机平面上定义。我们详细介绍了这些瓷砖的构造,并通过考虑高生物表面上的周期性边界条件来计算其霍夫史塔特蝴蝶。正如最近在一些常规双曲线砖上观察到的那样,这些蝴蝶并未表现出其欧几里得对应物的自相似结构,但仍然含有一些差距。我们还考虑双曲线kagome砖的能量光谱(这是双曲线骰子砖的双重),它显示了有趣的特征,例如对于磁场的某些特定值而产生的高度退化状态。对于这两个双曲线砖的家族,我们计算了霍夫斯塔特蝴蝶的主要间隙中的Chern数字,并提出了受欧几里得案例启发的间隙标签。最后,我们还研究了三角形的husimi仙人掌,这是双曲线kagome斜利家族中的一个极限情况,我们得出了其光谱与磁通量的精确表达。
Aharonov-Bohm caging is a localization mechanism stemming from the competition between the geometry and the magnetic field. Originally described for a tight-binding model in the dice lattice, this destructive interference phenomenon prevents any wavepacket spreading away from a strictly confined region. Accordingly, for the peculiar values of the field responsible for this effect, the energy spectrum consists of a discrete set of highly degenerate flat bands. In the present work, we show that Aharonov-Bohm cages are also found in an infinite set of hyperbolic dice tilings defined on a negatively curved hyperbolic plane. We detail the construction of these tilings and compute their Hofstadter butterflies by considering periodic boundary conditions on high-genus surfaces. As recently observed for some regular hyperbolic tilings, these butterflies do not manifest the self-similar structure of their Euclidean counterparts but still contain some gaps. We also consider the energy spectrum of hyperbolic kagome tilings (which are the dual of hyperbolic dice tilings), which displays interesting features, such as highly degenerate states arising for some particular values of the magnetic field. For these two families of hyperbolic tilings, we compute the Chern number in the main gaps of the Hofstadter butterfly and propose a gap labeling inspired by the Euclidean case. Finally, we also study the triangular Husimi cactus, which is a limiting case in the family of hyperbolic kagome tilings, and we derive an exact expression for its spectrum versus magnetic flux.