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arXiv 1008.1979cond-mat.mes-hallcond-mat.str-el
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nu = 5/2分数量子Hall态的局域电荷

Local Charge of the nu=5/2 Fractional Quantum Hall State

Vivek Venkatachalam, Amir Yacoby, Loren Pfeiffer, Ken West

摘要:

在二维和强磁场中的电子有效地失去了它们的动能,并显示出由库仑力支配的奇异行为。当系统中的电子与磁通量量子的比率接近5/2时,出现的唯一相关相被预测为与分数带电准粒子和基态简并度成指数增长,因为这些准粒子被引入。有趣的是,在许多基态之间转换的唯一方法是将分数激发编织在彼此周围,这是一种在量子信息处理中具有应用的性质。在这里,我们提出了第一次观察到的局域准粒子在nu = 5/2,仅限于水坑的混乱。使用局部静电计比较nu = 5/2和nu = 7/3的准粒子如何对这些水坑充电,我们能够提取这些状态的局部电荷比率。在几个无序配置和样品的平均值,我们发现的比例是4/3,这表明本地电荷是e/3在三分之七和e/4在五分之一,与理论预测一致。局域化的e/4准粒子的这种确认是必要的建议干涉实验,以测试统计和计算能力的状态在nu = 5/2。

英文摘要:

Electrons in two dimensions and strong magnetic fields effectively lose their kinetic energy and display exotic behavior dominated by Coulomb forces. When the ratio of electrons to magnetic flux quanta in the system is near 5/2, the unique correlated phase that emerges is predicted to be gapped with fractionally charged quasiparticles and a ground state degeneracy that grows exponentially as these quasiparticles are introduced. Interestingly, the only way to transform between the many ground states would be to braid the fractional excitations around each other, a property with applications in quantum information processing. Here we present the first observation of localized quasiparticles at nu=5/2, confined to puddles by disorder. Using a local electrometer to compare how quasiparticles at nu=5/2 and nu=7/3 charge these puddles, we are able to extract the ratio of local charges for these states. Averaged over several disorder configurations and samples, we find the ratio to be 4/3, suggesting that the local charges are e/3 at seven thirds and e/4 at five halves, in agreement with theoretical predictions. This confirmation of localized e/4 quasiparticles is necessary for proposed interferometry experiments to test statistics and computational ability of the state at nu=5/2.

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