Parafermion excitations in superfluid of quasi-molecular chains

TL;DR

This paper investigates a quantum phase transition in a system of dipoles in stacked one-dimensional lattices, revealing a transition to a chain superfluid phase characterized by parafermionic excitations, with results supported by Monte Carlo simulations.

Contribution

It introduces a novel quantum phase transition to a chain superfluid phase with parafermion excitations in dipolar lattice systems, connecting it to the $q=N$ Potts model universality class.

Findings

Transition belongs to the $q=N$ Potts model universality class.

Monte Carlo simulations support the theoretical predictions.

Detection scheme for chain superfluid of indirect excitons is proposed.

Abstract

We study a quantum phase transition in a system of dipoles confined in a stack of $N$ identical one-dimensional lattices (tubes) polarized perpendicularly to the lattices. In this arrangement the intra-lattice interaction is purely repulsive preventing the system collapse and the inter-lattice one is attractive. The dipoles may represent polar molecules or indirect excitons. The transition separates two phases; in one of them superfluidity (understood as algebraic decay of the corresponding correlation functions) takes place in each individual lattice, in the other (chain superfluid) the order parameter is the product of bosonic operators from all lattices. We argue that in the presence of finite inter-lattice tunneling the transition belongs to the universality class of the $q=N$ two-dimensional classical Potts model. For $N=2,3,4$ the corresponding low energy field theory is the model of Z$_N$ parafermions perturbed by the thermal operator. Results of Monte Carlo simulations are consistent with these predictions. The detection scheme for the chain superfluid of indirect excitons is outlined.