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arXiv 1507.02161cond-mat.mes-hallcond-mat.str-el
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分数量子霍尔效应Laughlin理论的推广

Generalization of Laughlin's Theory for the Fractional Quantum Hall Effect

Sudhansu S. Mandal

摘要:

受分数量子霍尔填充因子$ν= 1/m$的复合费米子(CF)理论中的准粒子波函数的启发,我考虑了一个合适的准粒子算子微分形式,作为Laughlin准粒子算子的修正形式,它再现了CF理论中预测的准粒子波函数.进一步考虑该算符的共轭作为准空穴算符,得到了一个新的$1/m$态的准空穴波函数。这些波函数中的每一个都被解释为从劳克林凝聚体的原始希尔伯特空间被驱逐到不同的希尔伯特子空间中的电子,同时仍然保持其与凝聚体中的电子的相关性(尽管改变了),使得被驱逐的电子相对于凝聚体中的电子表现为CF。有了这个解释,我表明,基态波函数的一般状态填充分数$ν_{n,m}^{\pm} = n/[n(m\mp 1)\pm 1]$,分别可以构造为相干叠加的$n$耦合Laughlin凝聚体和它们的共轭,形成在不同的希尔伯特子空间。相应的波函数,特别是令人惊讶的$ν_{n,m}^{-}$序列的状态,是相同的非相互作用CF理论中提出的。被认为是相互作用的CF的分数量子霍尔效应的状态也可以在相同的基础上被处理为描述为耦合凝聚体的突出的状态序列,其中一个是在不同的希尔伯特子空间中的非Laughlin凝聚体。此外,我预测,最低朗道能级的一半填充是一个量子临界点之间的相变两个拓扑不同的阶段,每个对应于一个家庭的状态。

英文摘要:

Motivated by the quasiparticle wavefunction in the composite fermion (CF) theory for fractional quantum Hall filling factor $ν= 1/m$, I consider a suitable quasiparticle operator in differential form, as a modified form of Laughlin's quasiparticle operator, that reproduces quasiparticle wave function as predicted in the CF theory. I further consider the conjugate of this operator as quasihole operator for obtaining a novel quasihole wave function for $1/m$ state. Each of these wave functions is interpreted as expelled electron into a different Hilbert subspace from the original Hilbert space of Laughlin condensate while still maintaining its correlation (although changed) with the electrons in the condensate such that the expelled electron behaves as a CF with respect to the electrons in the condensate. With this interpretation, I show that the ground state wavefunctions for general states at filling fractions $ν_{n,m}^{\pm} = n/[n(m\mp 1)\pm 1]$, respectively, can be constructed as coherent superposition of $n$ coupled Laughlin condensates and their conjugates, formed at different Hilbert subspaces. The corresponding wave functions, specially surprising for $ν_{n,m}^{-}$ sequence of states, are identical with those proposed in the theory of noninteracting CFs. The states which were considered as fractional quantum Hall effect of interacting CFs, can also be treated in the same footing as for the prominent sequences of states describing as the coupled condensates among which one is a non-Laughlin condensate in a different Hilbert subspace. Further, I predict that the half filling of the lowest Landau level is a quantum critical point for phase transitions between two topologically distinct phases each corresponding to a family of states.

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