Observation of half-integer thermal Hall conductance
Observation of half-integer thermal Hall conductance
复制标题
DOI：
10.1038/s41586-018-0184-1
复制
发表时间：
2018-07-12
期刊：
影响因子：
64.8
通讯作者：
Stern, Ady
中科院分区：
文献类型：
--
作者：
Banerjee, Mitali;Heiblum, Moty;Stern, Ady
物质的拓扑状态由拓扑不变量表征，拓扑不变量是物理量，其值被量化，并且不依赖于系统的细节（例如其形状，大小和杂质）。在这些量中，最容易探测的是霍尔电导，而这个量的分数值（单位为e（2）/h，其中e是电子电荷，h是普朗克常数）证明了拓扑有序态，它携带着带有分数电荷和任意子统计的准粒子。另一个拓扑不变量是热霍尔电导，这是很难测量。对于量子化的热霍尔电导，以kappa（0）为单位的分数值（kappa（0）= pi（2）k B（2）/（3 h），其中k（B）是玻尔兹曼常数）证明物质的状态是非阿贝尔的。这种非阿贝尔态导致基态简并，并在编织时进行拓扑幺正变换，这对于拓扑量子计算是有用的。本文报道了在第一激发朗道能级上对几个量子霍尔态的热霍尔电导的测量结果，发现5/2态的热霍尔电导与2.5 kappa（0）的半整数值相容，证明了它的非阿贝尔性质。
Topological states of matter are characterized by topological invariants, which are physical quantities whose values are quantized and do not depend on the details of the system (such as its shape, size and impurities). Of these quantities, the easiest to probe is the electrical Hall conductance, and fractional values (in units of e(2)/h, where e is the electronic charge and h is the Planck constant) of this quantity attest to topologically ordered states, which carry quasiparticles with fractional charge and anyonic statistics. Another topological invariant is the thermal Hall conductance, which is harder to measure. For the quantized thermal Hall conductance, a fractional value in units of kappa(0) (kappa(0) = pi(2)kB(2)/(3h), where k(B) is the Boltzmann constant) proves that the state of matter is non-Abelian. Such non-Abelian states lead to ground-state degeneracy and perform topological unitary transformations when braided, which can be useful for topological quantum computation. Here we report measurements of the thermal Hall conductance of several quantum Hall states in the first excited Landau level and find that the thermal Hall conductance of the 5/2 state is compatible with a half-integer value of 2.5 kappa(0), demonstrating its non-Abelian nature.