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.

在分数量子霍尔效应中，准粒子是具有分数电荷的集体激发，并在交换位置时显示分数统计数据。分数电荷会影响散粒噪声和充电能量等半经典特性，而分数统计量通过量子干涉最为明显。在这里，我们研究了双层石墨烯法布里-佩罗干涉仪中的分数统计。我们将干涉仪从库仑主导的模式调整为 Aharonov-Bohm 模式，包括整数和分数量子霍尔态。我们专注于填充因子 ν = 1/3 的分数量子霍尔态，跟踪准粒子的 Aharonov-Bohm 干涉的演变，同时独立改变通过干涉环的磁通量和环内的电荷密度。当它们的组合变化使得朗道填充保持 1/3 时，回路中的电荷密度会连续变化。然后，我们观察到原始的 Aharonov-Bohm 振荡，周期为 3 个磁通量，正如电子电荷 1/3 的准粒子所预期的那样。然而，当组合变化导致准粒子添加或移除的离散事件时，就会出现相跳并改变相演化。值得注意的是，在所有具有离散和连续电荷变化的情况下，平均相位始终增加 2π，每向回路中添加一个电子，正如准粒子所预期的那样，遵循分数统计。