Nontrivial ground-state degeneracies and generalized fractional excitations in the 1D lattice

TL;DR

This paper investigates a 1D lattice model where tuning interactions leads to nontrivial ground-state degeneracies and fractional excitations, resembling phenomena in quantum Hall systems and potential applications in topological quantum computing.

Contribution

It introduces a model with tunable interactions that produce fractional charges and ground-state degeneracies, extending the understanding of fractional excitations beyond traditional systems.

Findings

Emergence of nontrivial ground-state degeneracies.

Fractionally charged domain wall excitations.

Resemblance to non-Abelian statistics.

Abstract

We study a 1D lattice Hamiltonian, relevant for a wide range of interesting physical systems like, e.g., the quantum-Hall system, cold atoms or molecules in optical lattices, and TCNQ salts. Through a tuning of the interaction parameters and a departure from a strictly convex interaction, nontrivial ground-state degeneracies and fractionally charged excitations emerge. The excitations, being a generalization of the fractional charges known from the fractional quantum-Hall effect, appear as domain walls between inequivalent ground states and carry the charge +e/mq or -e/mq, where m is an integer and associated with the specified interaction, and v = p/q is the filling fraction in the lattice. The description points at an interesting resemblance to states connected to non-Abelian statistics, which is central for the concept of topological quantum computing.