Observation of a quarter of an electron charge at the ν=5/2 quantum Hall state
Observation of a quarter of an electron charge at the ν=5/2 quantum Hall state
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DOI：
10.1038/nature06855
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发表时间：
2008-04-17
期刊：
影响因子：
64.8
通讯作者：
Mahalu, D.
中科院分区：
文献类型：
--
作者：
Dolev, M.;Heiblum, M.;Mahalu, D.
分数量子霍尔效应是由强磁场下二维电子相关性产生的，其中 h/nu e(2) 值处的霍尔电阻平台与纵向电阻为零共存。 （这里 h 是普朗克常数，nu 是填充因子，e 是电子电荷。）电流沿着样品边缘流动，并由带电激励（准粒子）携带，其电荷是电子电荷的一部分。尽管早期的研究集中在 nu 的奇分母分数值上，但对偶分母 nu = 5/2 状态的观察引起了人们的极大兴趣。据推测，这种状态的特征是电荷为 e/4 的准粒子，其统计数据是“非阿贝尔”的——换句话说，交换两个准粒子可以将系统的状态修改为不同的状态，而不是像费米子或玻色子那样仅仅添加一个相。因此，这些准粒子可能有助于构建拓扑量子计算机。在这里，我们报告了通过在 nu = 5/2 状态下划分边缘电流生成的散粒噪声数据，与准粒子的电荷为 e/4 一致，但与其他可能值（例如 e/2 和 e）不一致。尽管这一发现并没有证明 nu= 5/2 态的非阿贝尔性质，但它是全面理解这些新分数电荷的第一步。
The fractional quantum Hall effect, where plateaus in the Hall resistance at values of h/nu e(2) coexist with zeros in the longitudinal resistance, results from electron correlations in two dimensions under a strong magnetic field. ( Here h is Planck's constant, nu the filling factor and e the electron charge.) Current flows along the sample edges and is carried by charged excitations ( quasiparticles) whose charge is a fraction of the electron charge. Although earlier research concentrated on odd denominator fractional values of nu, the observation of the even denominator nu = 5/2 state sparked much interest. This state is conjectured to be characterized by quasiparticles of charge e/4, whose statistics are 'non- abelian' - in other words, interchanging two quasiparticles may modify the state of the system into a different one, rather than just adding a phase as is the case for fermions or bosons. As such, these quasiparticles may be useful for the construction of a topological quantum computer. Here we report data on shot noise generated by partitioning edge currents in the nu = 5/2 state, consistent with the charge of the quasiparticle being e/4, and inconsistent with other possible values, such as e/2 and e. Although this finding does not prove the non- abelian nature of the nu= 5/2 state, it is the first step towards a full understanding of these new fractional charges.