Measurement of filling factor 5/2 quasiparticle interference with observation of charge e/4 and e/2 period oscillations
Measurement of filling factor 5/2 quasiparticle interference with observation of charge e/4 and e/2 period oscillations
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DOI：
10.1073/pnas.0812599106
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发表时间：
2008-07
期刊：
影响因子：
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通讯作者：
R. Willett;L. Pfeiffer;K. West
中科院分区：
文献类型：
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作者：
R. Willett;L. Pfeiffer;K. West
低维电子系统中的一个长期存在的问题是5/2分数量子霍尔（Fractional quantum Hall，缩写为FWHH）态的性质：它的基元激发是阐明态性质的焦点，也是进行拓扑量子计算方法的候选者。干涉测量装置可用于操纵和测量量子霍尔边缘激发。在这里，我们使用一个小面积的边缘态干涉仪，旨在观察准粒子干涉效应。观察到与Aharonov-Bohm效应细节一致的整数量子霍尔和Hohm态（填充因子ν = 2，5/3和7/3）的振荡，其周期对应于它们各自的电荷和磁场位置。用这些因子作为电荷校准，在v = 5/2和最低温度下观察到与准粒子电荷e/4一致的通过器件的周期性传输。这项工作的主要发现是，除了这些e/4振荡之外，在5/2 ν和最低温度下也观察到对应于e/2的周期结构。的e/4和e/2振荡的性能进行检查与设备的灵敏度足以观察温度演变的5/2准粒子干涉。在准粒子干涉的模型中，有效e/2周期的存在可以凭经验反映e/2准粒子电荷，或者可以反映e/4准粒子在干涉仪周围的多次通过。这些结果进行了讨论的e/4准粒子激发可能具有非阿贝尔统计的图片。这些研究表明，有能力进行干涉测量5/2激发，并揭示了解这种状态及其激发的重要属性。
A standing problem in low-dimensional electron systems is the nature of the 5/2 fractional quantum Hall (FQH) state: Its elementary excitations are a focus for both elucidating the state's properties and as candidates in methods to perform topological quantum computation. Interferometric devices may be used to manipulate and measure quantum Hall edge excitations. Here we use a small-area edge state interferometer designed to observe quasiparticle interference effects. Oscillations consistent in detail with the Aharonov–Bohm effect are observed for integer quantum Hall and FQH states (filling factors ν = 2, 5/3, and 7/3) with periods corresponding to their respective charges and magnetic field positions. With these factors as charge calibrations, periodic transmission through the device consistent with quasiparticle charge e/4 is observed at ν = 5/2 and at lowest temperatures. The principal finding of this work is that, in addition to these e/4 oscillations, periodic structures corresponding to e/2 are also observed at 5/2 ν and at lowest temperatures. Properties of the e/4 and e/2 oscillations are examined with the device sensitivity sufficient to observe temperature evolution of the 5/2 quasiparticle interference. In the model of quasiparticle interference, this presence of an effective e/2 period may empirically reflect an e/2 quasiparticle charge or may reflect multiple passes of the e/4 quasiparticle around the interferometer. These results are discussed within a picture of e/4 quasiparticle excitations potentially possessing non-Abelian statistics. These studies demonstrate the capacity to perform interferometry on 5/2 excitations and reveal properties important for understanding this state and its excitations.