We present an alternative derivation for the macroscopic theory of edge excitations of the fractional-quantum-Hall liquid. The predictions of the macroscopic theory are compared with numerical results for finite systems.
Based on the composite fermion approach, we derive a microscopic theory describing the low-lying edge excitations in the fractional quantum Hall liquid with ν=ϕ~ν∗+1ν∗. For ν∗>0, it is found that the composite fermion model reduces to an SU(ν∗) Calogero-Sutherland model in the one-dimensional limit, whereas it is not exact soluble for ν∗<0. However, the ground states in both cases can be found and the low-lying excitations can be shown the chiral Luttinger liquid behaviors since a gap exists between the right- and left-moving sectors in each branch of the azimuthal excitations.
We present a theory of the collective excitation spectrum in the fractional quantum Hall-effect regimes, in analogy with Feynman's theory for helium. The spectrum is in excellent quantitative agreement with the numerical results of Haldane. Within this approximation we prove that a finite gap is generic to any liquid state in the extreme quantum limit and that in this single-mode approximation gapless excitations can arise only as Goldstone modes for ground states with broken translation symmetry.
Motivated by recent experimental advancements in scanning optical stroboscopic confocal microscopy and spectroscopy measurements, which have facilitated exceptional energy-space-time resolution for investigating edge and bulk dynamics in fractional quantum Hall systems, we formulated a model for the pump-probe process on the edge. Starting with a ground state, we applied a tip potential near the fractional quantum Hall liquid edge, which was subsequently turned off after a defined time duration. By examining how the specific nature of the tip potential influences the evolution of the wave function and its distribution in energy spectrum, we identify that quench dynamics of the edge pulse leads to excitations that spread both along the edge and perpendicularly into the bulk. Moreover, magnetoroton excitations are predominant among the bulk excitations. These results align well with the experimental observations. Furthermore, we analyzed the effects of the tip's position, intensity, and duration on the dynamics.
This study builds upon the work of Palacios and MacDonald [Phys. Rev. Lett. 76, 118 (1996)], wherein they identify the bosonic excitations of Wen's approach for the edge of the 1∕3 fractional quantum Hall state with certain operators introduced by Stone. Using a quantum Monte Carlo method, we extend this approach to larger systems containing up to 40 electrons and obtain more accurate thermodynamic limits for various matrix elements for a short-range interaction. The results are in agreement with those of Palacios and MacDonald for small systems, but offer further insight into a detailed approach to the thermodynamic limit. For the short range interaction, the results are consistent with chiral Luttinger liquid predictions. We also study excitations using the Coulomb ground state for up to nine electrons to ascertain the effect of interactions on the results; in this case, our tests of the chiral Luttinger liquid approach are inconclusive.
We derive a microscopic model describing low-lying edge excitations in a fractional quantum Hall liquid with $\ensuremath{\nu}={\ensuremath{\nu}}^{*}/(\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\varphi}}{\ensuremath{\nu}}^{*}+1).$ For ${\ensuremath{\nu}}^{*}>0,$ it is found that the composite-fermion model reduces to an $\mathrm{SU}({\ensuremath{\nu}}^{*})$ Calogero-Sutherland model in a dimension reduction, whereas it is not exactly soluble for ${\ensuremath{\nu}}^{*}<0.$ However, the ground states in both cases can be found, and the low-lying excitations can show chiral Luttinger-liquid behaviors. On the other hand, we show that the finite-temperature behavior of the $G\ensuremath{-}T$ curve will deviate from the prediction of the chiral Luttinger liquid. We also point out that the suppression of the ``spin'' degrees of freedom agrees with very recent experiments by Chang et al. [Phys. Rev. Lett. 77, 2538 (1996)]. The two-boson model of Lee and Wen (preprint, cond-mat/9801318) is described microscopically.