On the Coexistence of Diagonal and off-Diagonal Long-Range Order, a Monte Carlo Study

TL;DR

This study uses Monte Carlo simulations to explore the coexistence of crystalline and superfluid long-range order in 2D lattice bosons at zero temperature, revealing new insights into phase behavior.

Contribution

It provides the first Monte Carlo evidence of coexistence of diagonal and off-diagonal long-range order in soft-core bosons, contrasting with mean-field predictions.

Findings

Coexistence of crystalline and superfluid order confirmed

Critical exponents for phase transitions determined

Differences between hard and soft-core bosons discussed

Abstract

The zero temperature properties of interacting 2 dimensional lattice bosons are investigated. We present Monte Carlo data for soft-core bosons that demonstrate the existence of a phase in which crystalline long-range order and off-diagonal long-range order (superfluidity) coexist. We comment on the difference between hard and soft-core bosons and compare our data to mean-field results that predict a larger coexistence region. Furthermore, we determine the critical exponents for the various phase transitions.