双层石墨烯中分数量子霍尔态的阿哈罗诺夫-玻姆干涉和统计相位跃变演化

Aharonov-Bohm interference and statistical phase-jump evolution in fractional quantum Hall states in bilayer graphene.

作者信息

Kim Jehyun, Dev Himanshu, Kumar Ravi, Ilin Alexey, Haug André, Bhardwaj Vishal, Hong Changki, Watanabe Kenji, Taniguchi Takashi, Stern Ady, Ronen Yuval

机构信息

Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel.

Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan.

出版信息

Nat Nanotechnol. 2024 Nov;19(11):1619-1626. doi: 10.1038/s41565-024-01751-w. Epub 2024 Aug 20.

Abstract

In the fractional quantum Hall effect, quasiparticles are collective excitations that have a fractional charge and show fractional statistics as they interchange positions. While the fractional charge affects semi-classical characteristics such as shot noise and charging energies, fractional statistics is most notable through quantum interference. Here we study fractional statistics in a bilayer graphene Fabry-Pérot interferometer. We tune the interferometer from the Coulomb-dominated regime to the Aharonov-Bohm regime, both for integer and fractional quantum Hall states. Focusing on the fractional quantum Hall state with a filling factor ν = 1/3, we follow the evolution of the Aharonov-Bohm interference of quasiparticles while varying the magnetic flux through an interference loop and the charge density within the loop independently. When their combined variation is such that the Landau filling remains 1/3, the charge density in the loop varies continuously. We then observe pristine Aharonov-Bohm oscillations with a period of three flux quanta, as expected for quasiparticles of one-third of the electron charge. Yet, when the combined variation leads to discrete events of quasiparticle addition or removal, phase jumps emerge and alter the phase evolution. Notably, across all cases with discrete and continuous charge variation, the average phase consistently increases by 2π with each addition of one electron to the loop, as expected for quasiparticles, obeying fractional statistics.

摘要

在分数量子霍尔效应中,准粒子是集体激发态,它们具有分数电荷,并且在交换位置时表现出分数统计特性。虽然分数电荷会影响诸如散粒噪声和充电能量等半经典特性,但分数统计特性在量子干涉中最为显著。在此,我们研究双层石墨烯法布里 - 珀罗干涉仪中的分数统计特性。我们将干涉仪从库仑主导区域调谐到阿哈罗诺夫 - 玻姆区域,涵盖整数和分数量子霍尔态。聚焦于填充因子ν = 1/3的分数量子霍尔态,我们在独立改变通过干涉环的磁通量和环内电荷密度的同时,跟踪准粒子的阿哈罗诺夫 - 玻姆干涉的演化。当它们的组合变化使得朗道填充保持为1/3时,环内的电荷密度连续变化。然后,我们观察到具有三个磁通量子周期的纯净阿哈罗诺夫 - 玻姆振荡,这与电子电荷三分之一的准粒子预期一致。然而,当组合变化导致准粒子添加或移除的离散事件时,相位跳跃出现并改变相位演化。值得注意的是,在所有离散和连续电荷变化的情况下,随着每次向环中添加一个电子,平均相位如准粒子所预期的那样,遵循分数统计特性,始终增加2π。

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