Topological Thouless pumping of ultracold fermions
Topological Thouless pumping of ultracold fermions
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DOI：
10.1038/nphys3622
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发表时间：
2016-04-01
期刊：
影响因子：
19.6
通讯作者：
Takahashi, Yoshiro
中科院分区：
文献类型：
--
作者：
Nakajima, Shuta;Tomita, Takafumi;Takahashi, Yoshiro
如果在时间上缓慢且周期性地调制一维周期势中的电子气，则即使在没有电压偏置的情况下也可以传输该电子气。值得注意的是，每个周期的转移电荷只对参数空间中路径的拓扑结构敏感。虽然这种所谓的无管电荷泵是在三十多年前首次提出的(1)，但它至今还没有实现。本文报道了在动态控制的光学超晶格中利用超冷费米子原子进行拓扑无思考泵浦的实验结果。我们观察到由于泵浦而引起的原子云的位移，并从这种位移中提取了泵浦过程的拓扑不变性。我们通过改变抽运路径的拓扑结构来证明无Thouless抽运的拓扑性质，并通过改变抽运速度和温度来验证拓扑泵确实工作在量子区域。
An electron gas in a one-dimensional periodic potential can be transported even in the absence of a voltage bias if the potential is slowly and periodically modulated in time. Remarkably, the transferred charge per cycle is sensitive only to the topology of the path in parameter space. Although this so-called Thouless charge pump was first proposed more than thirty years ago(1), it has not yet been realized. Here we report the demonstration of topological Thouless pumping using ultracold fermionic atoms in a dynamically controlled optical superlattice. We observe a shift of the atomic cloud as a result of pumping, and extract the topological invariance of the pumping process from this shift. We demonstrate the topological nature of the Thouless pump by varying the topology of the pumping path and verify that the topological pump indeed works in the quantum regime by varying the speed and temperature.