Mach-Zehnder interferometry using spin- and valley-polarized quantum Hall edge states in graphene.
Mach-Zehnder interferometry using spin- and valley-polarized quantum Hall edge states in graphene.
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DOI：
10.1126/sciadv.1700600
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发表时间：
2017-08
期刊：
影响因子：
13.6
通讯作者：
Yacoby A
中科院分区：
文献类型：
--
作者：
Wei DS;van der Sar T;Sanchez-Yamagishi JD;Watanabe K;Taniguchi T;Jarillo-Herrero P;Halperin BI;Yacoby A
我们在石墨烯的pn结处实现了一种具有量子霍尔边缘通道的电子马赫 - 曾德尔干涉仪。
限制在二维平面内，强磁场中的电子在一维量子霍尔通道中沿边缘运动，这些通道可防止背向散射。这些通道可用作单色光束的固态类似物，为研究电子干涉提供了一个独特的平台。电子干涉测量法被视为通过双粒子干涉研究分数量子统计、非阿贝尔统计以及量子纠缠的最有前途的途径之一。然而，创建一个电子 - 电子相互作用起重要作用的边缘通道干涉仪需要一个纯净的系统和长相干长度。我们利用在石墨烯的pn结处共传播的自旋和谷极化边缘通道，实现了可见度高达98%的电子马赫 - 曾德尔干涉仪，这一可见度创下了纪录。我们发现，沿着石墨烯物理边缘的相同自旋边缘通道之间的通道间散射可用于形成分束器，而沿着栅极定义的界面不存在通道间散射可用于形成孤立的干涉仪臂。令人惊讶的是，我们的干涉仪在能量比在GaAs/AlGaAs量子阱的开创性实验中所观察到的能量大一个数量级的情况下，对退相效应具有鲁棒性。我们的结果揭示了边缘通道平衡的性质，并为研究奇异电子统计和量子现象开辟了新的可能性。
We realize an electronic Mach-Zehnder interferometer with quantum Hall edge channels along a pn junction in graphene. Confined to a two-dimensional plane, electrons in a strong magnetic field travel along the edge in one-dimensional quantum Hall channels that are protected against backscattering. These channels can be used as solid-state analogs of monochromatic beams of light, providing a unique platform for studying electron interference. Electron interferometry is regarded as one of the most promising routes for studying fractional and non-Abelian statistics and quantum entanglement via two-particle interference. However, creating an edge-channel interferometer in which electron-electron interactions play an important role requires a clean system and long phase coherence lengths. We realize electronic Mach-Zehnder interferometers with record visibilities of up to 98% using spin- and valley-polarized edge channels that copropagate along a pn junction in graphene. We find that interchannel scattering between same-spin edge channels along the physical graphene edge can be used to form beamsplitters, whereas the absence of interchannel scattering along gate-defined interfaces can be used to form isolated interferometer arms. Surprisingly, our interferometer is robust to dephasing effects at energies an order of magnitude larger than those observed in pioneering experiments on GaAs/AlGaAs quantum wells. Our results shed light on the nature of edge-channel equilibration and open up new possibilities for studying exotic electron statistics and quantum phenomena.
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