Finite-Temperature N\'eel Ordering of Fluctuations in a Plaquette Orbital Model

TL;DR

This paper introduces a pseudospin model related to the compass model, demonstrating finite-temperature Neel ordering of energy fluctuations in classical and quantum spins, with implications for quantum information protection.

Contribution

It presents a new pseudospin model accessible experimentally and clarifies the stability of ordered states with impurities, contrasting previous conflicting results.

Findings

Finite-temperature Neel ordering of energy fluctuations observed

Order persists in the presence of quenched impurities

Results differ from earlier studies on impurity effects

Abstract

We present a pseudospin model which should be experimentally accessible using solid-state devices and, being a variation on the compass model, adds to the toolbox for the protection of qubits in the area of quantum information. Using Monte Carlo methods, we find for both classical and quantum spins in two and three dimensions Ising-type Neel ordering of energy fluctuations at finite temperatures without magnetic order. We also readdress the controversy concerning the stability of the ordered state in the presence of quenched impurities and present numerical results which are at clear variance with earlier claims in the literature.