Effective Fractonic Behavior in a Two-Dimensional Exactly Solvable Spin Liquid

TL;DR

This paper introduces an exactly solvable 2D $ ext{Z}_N$ clock model exhibiting fractonic behavior, with distinct low-energy regimes described by different topological field theories and a characteristic time scale separating fractonic and mobile phases.

Contribution

It presents a novel exactly solvable lattice model with fractonic properties and analyzes its continuum limits, revealing two distinct regimes with different topological field theories.

Findings

Low-energy physics shows UV/IR mixing and restricted mobility of excitations.

A characteristic time scale grows exponentially with $N^2$, separating fractonic and mobile phases.

Effective field theories differ: fractonic Chern-Simons-like action below the scale, mutual Chern-Simons above.

Abstract

In this work we propose a $\mathbb{Z}_N$ clock model which is exactly solvable on the lattice. We find exotic properties for the low-energy physics, such as UV/IR mixing and excitations with restricted mobility, that resemble fractonic physics from higher dimensional models. We then study the continuum descriptions for the lattice system in two distinct regimes and find two qualitative distinct field theories for each one of them. A characteristic time scale that grows exponentially fast with $N^2$ (and diverges rapidly as a function of system parameters) separates these two regimes. For times below this scale, the system is described by an effective fractonic Chern-Simons-like action, where higher-form symmetries prevent quasiparticles from hoping. In this regime, the system behaves effectively as a fracton as isolated particles, in practice, never leave their original position. Beyond the large characteristic time scale, the excitations are mobile and the effective field theory is given by a pure mutual Chern-Simons action. In this regime, the UV/IR properties of the system are captured by a peculiar realization of the translation group.