论文标题
对比的晶格几何依赖性与独立数量:浆果曲率,能量差距和动力学的分歧
Contrasting lattice geometry dependent versus independent quantities: ramifications for Berry curvature, energy gaps, and dynamics
论文作者
论文摘要
在周期性晶格电位中电子,光子或冷原子动力学的紧密结合描述中,粒子运动是用在与晶格中物理轨道相对应的离散位点的抽象网络上跳跃和电势来描述的。轨道的物理属性,包括其在三维空间中的位置,是独立的信息。在本文中,我们确定了独立于几何学的概念:仅取决于紧密结合参数(而不是关于轨道几何学的明确信息)的任何物理数量或可观察到的概念,据说是“几何独立的”。频带结构本身,例如二维系统中频带的Chern数字是与几何学无关的,而Bloch-Band Berry曲率的几何学依赖性。仔细识别几何依赖性与独立量可以用作约束各种结果的新原理。通过将独立于某些类别的相互作用系统的几何形状依赖性扩展到显然是与几何学无关的相互作用系统的概念,我们对分数Chern绝缘子的多体能量差距与Blilloch Band Berry curvature在Brillouin Zone的多体能量之间存在了新的启示。我们进一步探讨了半经典波数据包动力学的几何依赖性,并使用此原理来显示两种不同类型的霍尔响应测量结果如何给出明显不同的结果,因为一个事实是一个几何学依赖性,而另一个是几何独立的。类似的考虑因素适用于电子和自旋系统中的异常热室反应。
In the tight-binding description of electronic, photonic, or cold atomic dynamics in a periodic lattice potential, particle motion is described in terms of hopping amplitudes and potentials on an abstract network of discrete sites corresponding to physical orbitals in the lattice. The physical attributes of the orbitals, including their locations in three-dimensional space, are independent pieces of information. In this paper we identify a notion of geometry-independence: any physical quantity or observable that depends only on the tight-binding parameters (and not on the explicit information about the orbital geometry) is said to be "geometry-independent." The band structure itself, and for example the Chern numbers of the bands in a two-dimensional system, are geometry-independent, while the Bloch-band Berry curvature is geometry-dependent. Careful identification of geometry-dependent versus independent quantities can be used as a novel principle for constraining a variety of results. By extending the notion of geometry-independence to certain classes of interacting systems, where the many-body energy gap is evidently geometry-independent, we shed new light on a hypothesized relation between many-body energy gaps of fractional Chern insulators and the uniformity of Bloch band Berry curvature in the Brillouin zone. We furthermore explore the geometry-dependence of semiclassical wave packet dynamics, and use this principle to show how two different types of Hall response measurements may give markedly different results due to the fact that one is geometry-dependent, while the other is geometry-independent. Similar considerations apply for anomalous thermal Hall response, in both electronic and spin systems.