Anyon Dispersion in Aharonov-Casher Bands and Implications for Twisted MoTe${}_2$

TL;DR

This paper develops an analytical theory of anyon dispersion in fractional quantum anomalous Hall states within Aharonov-Casher bands, revealing how band geometry and interactions influence quasihole dynamics, with implications for twisted MoTe${}_2$.

Contribution

It introduces a microscopic framework for calculating anyon dispersion in FQAH states, linking band geometry, interactions, and Berry phases, and extends to multiple quasiholes.

Findings

Quasihole bandwidth increases with band inhomogeneity and interaction range.

Estimated quasihole bandwidth of ~1 meV for twisted MoTe${}_2$, indicating potential for itinerant-anyon physics.

Developed a microscopic Lagrangian approach capturing the effects of quantum geometry and Berry phases.

Abstract

The discovery of fractional quantum anomalous Hall (FQAH) states in two-dimensional heterostructures has opened the door to realizing phases of dispersing anyons. Here, we develop an analytically controlled theory of anyon dispersion in FQAH states realized in ideal or Aharonov-Casher (AC) bands by projecting interactions onto the space of Laughlin quasiholes. Constructing quasihole momentum eigenstates allows efficient evaluation of the single quasihole dispersion using Monte Carlo. We find that the quasihole bandwidth grows with increasing quantum-geometry inhomogeneity of the AC band and with increasing interaction screening length. For realistic parameters relevant to the bands of twisted MoTe${}_2$, the quasihole bandwidth is of order 1 meV, suggesting that itinerant-anyon physics may play an important role in sufficiently clean samples. Furthermore, we develop a microscopic Lagrangian framework in terms of a quasihole guiding-center coordinate, which reproduces the momentum-space formula for the dispersion. This approach reveals that quasihole dispersion originates from the combined effects of an interaction-generated periodic potential, arising from non-uniform quantum geometry of the single particle bands, and the quasihole many-body Berry phase arising from the background magnetic field. The latter endows the guiding-center coordinate with a noncommutative structure, converting the periodic potential into a finite dispersion. Finally, we outline how this framework generalizes to multiple quasiholes, enabling a microscopic theory of charged excitations in FQAH systems that retains only the anyon degrees of freedom.