Jo M, Brasseur P, Assouline A, Fleury G, Sim H-S, Watanabe K, Taniguchi T, Dumnernpanich W, Roche P, Glattli D C, Kumada N, Parmentier F D, Roulleau P
SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif sur Yvette Cedex France.
Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea.
Phys Rev Lett. 2021 Apr 9;126(14):146803. doi: 10.1103/PhysRevLett.126.146803.
Graphene is a very promising test bed for the field of electron quantum optics. However, a fully tunable and coherent electronic beam splitter is still missing. We report the demonstration of electronic beam splitters in graphene that couple quantum Hall edge channels having opposite valley polarizations. The electronic transmission of our beam splitters can be tuned from zero to near unity. By independently setting the beam splitters at the two corners of a graphene p-n junction to intermediate transmissions, we realize a fully tunable electronic Mach-Zehnder interferometer. This tunability allows us to unambiguously identify the quantum interferences due to the Mach-Zehnder interferometer, and to study their dependence with the beam-splitter transmission and the interferometer bias voltage. The comparison with conventional semiconductor interferometers points toward universal processes driving the quantum decoherence in those two different 2D systems, with graphene being much more robust to their effect.
石墨烯是电子量子光学领域一个非常有前景的试验平台。然而，一个完全可调谐且相干的电子分束器仍然缺失。我们报道了在石墨烯中实现电子分束器的演示，该分束器耦合具有相反谷极化的量子霍尔边缘通道。我们的分束器的电子传输可以从零调谐到接近 unity。通过将石墨烯 p-n 结两个角上的分束器独立设置为中间传输，我们实现了一个完全可调谐的电子马赫-曾德尔干涉仪。这种可调谐性使我们能够明确识别由马赫-曾德尔干涉仪引起的量子干涉，并研究它们与分束器传输和干涉仪偏置电压的依赖关系。与传统半导体干涉仪的比较表明，在这两种不同的二维系统中存在驱动量子退相干的普遍过程，而石墨烯对其效应的耐受性要强得多。
