Fractional quantization of the topological charge pumping in a one-dimensional superlattice
Fractional quantization of the topological charge pumping in a one-dimensional superlattice
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DOI：
10.1103/physrevb.91.125411
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发表时间：
2014-08
影响因子：
3.7
通讯作者：
P. Marra;R. Citro;C. Ortix
中科院分区：
文献类型：
--
作者：
P. Marra;R. Citro;C. Ortix
一维量子电荷泵在每个泵浦周期中传输量化电荷。这种量子化在拓扑上是稳健的，类似于量子霍尔效应。相反，在泵浦周期的一小部分内传输的电荷通常是未量化的。然而，我们表明，在参数空间中具有特定对称性的情况下，在泵浦周期的明确定义的分数处传输的电荷被量化为陈数的整数分数。我们在一维 Harper-Hofstadter 模型中对此进行了说明，并表明拓扑电荷泵的分数量化与所考虑的特定边界条件无关。我们进一步讨论了这种现象与光学超晶格中冷原子气体的相关性。
A one-dimensional quantum charge pump transfers a quantized charge in each pumping cycle. This quantization is topologically robust being analogous to the quantum Hall effect. The charge transferred in a fraction of the pumping period is instead generally unquantized. We show, however, that with specific symmetries in parameter space the charge transferred at well-defined fractions of the pumping period is quantized as integer fractions of the Chern number. We illustrate this in a one-dimensional Harper-Hofstadter model and show that the fractional quantization of the topological charge pumping is independent of the specific boundary conditions taken into account. We further discuss the relevance of this phenomenon for cold atomic gases in optical superlattices.