Analytic Wavefunctions for Neutral Bulk Excitations in Fractional Quantum Hall Fluids

TL;DR

This paper introduces simple analytic wavefunctions for neutral excitations in fractional quantum Hall states, enabling calculation of the quadrupole gap and extending plasma analogy to neutral modes.

Contribution

It presents a new scheme for deriving analytic wavefunctions for neutral excitations in FQH states, applicable to various modes including magneto-roton and neutral fermions.

Findings

Analytic wavefunctions for neutral excitations are derived.

Quadrupole gap can be computed in the thermodynamic limit.

Extended plasma analogy to neutral excitations.

Abstract

We show the model wavefunctions for the neutral collective modes in fractional quantum Hall (FQH) states have simple analytic forms obtained from judicially reducing the powers of selected pairs in the ground state Jastrow factor. This scheme of "pair excitations" works for the magneto-roton modes of single-component Abelian and non-Abeliean FQH states, as well as the neutral fermion mode for the Moore-Read (MR) state. The analytic wavefunctions allow us to compute the "quadrupole gap" of the magneto-roton mode in the thermodynamic limit, which was previously inaccessible to the numerics. The quadrupole gap is related to the fusion of the charges in the two-dimensional plasma picture, extending the plasma analogy to neutral excitations. A lattice diagrammatic method of representing these many-body wavefunctions and FQH elementary excitations is also presented.