Algebraic geometry of the multilayer model of the fractional quantum Hall effect on a torus
Igor Burban, Semyon Klevtsov
TL;DR
This work builds a rigorous algebro-geometric framework for Keski-Vakkuri–Wen multilayer fractional quantum Hall states on a torus. It constructs a holomorphic magnetic vector bundle 𝔅 on the g-fold torus A whose fibers recover the KV–Wen ground-state spaces, and proves 𝔅 is simple and semi-homogeneous with a first Chern class computable from the adjunct K^♯, yielding a total Chern class c(𝔅) = (1 + c1(𝔅)/δ)^δ. Two natural hermitian metrics induce Bott–Chern connections, which are projectively flat in the canonical cases, linking the center-of-mass dynamics and the many-body Hilbert space to the differential-geometric structure. Using Fourier–Mukai transforms on abelian varieties, the paper identifies 𝔅 as the FM image of a line bundle and analyzes its dual and restricted forms, deriving explicit expressions for c1 and slope. The restricted bundle 𝕌 on the diagonal E has slope −ρ/δ and is stable precisely when K is primary, with Jain fractions arising as slopes in key examples, thereby connecting algebro-geometric invariants to fractional quantum Hall data.
Abstract
In 1993 Keski-Vakkuri and Wen introduced a model for the fractional quantum Hall effect based on multilayer two-dimensional electron systems satisfying quasi-periodic boundary conditions. Such a model is essentially specified by a choice of a complex torus $E$ and a symmetric positively definite matrix $K$ of size $g$ with positive integral coefficients. The space of the corresponding wave functions turns out to be $δ$-dimensional, where $δ$ is the determinant of $K$. We construct a hermitian holomorphic bundle of rank $δ$ on the abelian variety $A$ (which is the $g$-fold product of the torus $E$ with itself), whose fibres can be identified with the space of wave function of Keski-Vakkuri and Wen. A rigorous construction of this "magnetic bundle" involves the technique of Fourier-Mukai transforms on abelian varieties. This bundle turns out to be simple and semi-homogeneous. This bundle can be equipped with two different (and natural) hermitian metrics: the one coming from the center-of-mass dynamics and the one coming from the Hilbert space of the underlying many-body system. We prove that the canonical Bott-Chern connection of the first hermitian metric is always projectively flat and give sufficient conditions for this property for the second hermitian metric.
