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arXiv 1906.00342cond-mat.mes-hallquant-ph
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分数量子霍尔效应中的Angular momentum

Angular momentum in the fractional quantum Hall effect

S. J. van Enk

摘要:

假设一个经典电子在正$z$方向的恒定磁场的影响下被限制在$xy$平面内运动。然后,它以相对于轨道中心的固定正角动量$L_z$穿过圆形轨道。一个未被充分认识的事实是,基态(所谓的最低朗道能级)中电子的量子波函数具有方位角依赖性$\propto \exp(-imϕ) $与$m\geq 0$,这似乎与具有正角动量的经典电子相矛盾。我们在这里表明,量子数$m$与规范无关的意义不是角动量,而是量子化了电子轨道中心到原点的距离,并且电子的物理角动量是正的,在最低朗道能级上与$m$无关。我们注意到,关于分数量子霍尔效应的一些教科书和一些原始文献确实发现了具有看似正确的方位角形式$\propto\exp(+imϕ)$的波函数,但是仅仅是由于改变了符号(例如,通过混淆不同的惯例)在通往该结果的道路上的某个地方。

英文摘要:

Suppose a classical electron is confined to move in the $xy$ plane under the influence of a constant magnetic field in the positive $z$ direction. It then traverses a circular orbit with a fixed positive angular momentum $L_z$ with respect to the center of its orbit. It is an underappreciated fact that the quantum wave functions of electrons in the ground state (the so-called lowest Landau level) have an azimuthal dependence $\propto \exp(-imϕ) $ with $m\geq 0$, seemingly in contradiction with the classical electron having positive angular momentum. We show here that the gauge-independent meaning of that quantum number $m$ is not angular momentum, but that it quantizes the distance of the center of the electron's orbit from the origin, and that the physical angular momentum of the electron is positive and independent of $m$ in the lowest Landau levels. We note that some textbooks and some of the original literature on the fractional quantum Hall effect do find wave functions that have the seemingly correct azimuthal form $\propto\exp(+imϕ)$ but only on account of changing a sign (e.g., by confusing different conventions) somewhere on the way to that result.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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