Quantum Hall effect in momentum space

TL;DR

This paper proposes a theoretical framework for observing a quantum Hall effect in momentum space within topologically nontrivial lattice models under harmonic trapping, supported by numerical simulations and potential experimental platforms.

Contribution

It introduces a momentum-space analog of the quantum Hall effect using the Niu-Thouless-Wu formulation in a toroidal Brillouin zone, extending to interacting models and experimental considerations.

Findings

Numerical demonstration of the momentum-space quantum Hall effect in the Harper-Hofstadter model.

Identification of real-space trap center control as a means to manipulate momentum-space flux.

Discussion of experimental platforms for realizing the momentum-space quantum Hall effect.

Abstract

We theoretically discuss a momentum-space analog of the quantum Hall effect, which could be observed in topologically nontrivial lattice models subject to an external harmonic trapping potential. In our proposal, the Niu-Thouless-Wu formulation of the quantum Hall effect on a torus is realized in the toroidally shaped Brillouin zone. In this analogy, the position of the trap center in real space controls the magnetic fluxes that are inserted through the holes of the torus in momentum space. We illustrate the momentum-space quantum Hall effect with the noninteracting trapped Harper-Hofstadter model, for which we numerically demonstrate how this effect manifests itself in experimental observables. Extension to the interacting trapped Harper-Hofstadter model is also briefly considered. We finally discuss possible experimental platforms where our proposal for the momentum-space quantum Hall effect could be realized.