Phase diagram of the two-component bosonic system with pair hopping in synthetic dimension

TL;DR

This study maps the phase diagram of a two-component bosonic system with pair hopping in a synthetic dimension, revealing how symmetry breaking influences superfluidity, Mott phases, and demixing effects.

Contribution

It demonstrates that non-integer Mott and molecular superfluid phases require pair hopping with broken interexchange symmetry, expanding understanding of phase behavior in such systems.

Findings

Super-counter-fluidity regions shrink with symmetry breaking.

Non-integer Mott and molecular superfluid phases depend on pair hopping and broken symmetry.

Interspecies repulsion leads to incomplete demixing.

Abstract

We systematically study the ground-state phase diagrams and the demixing effect of a two-dimensional two-component bosonic system with pair hopping in synthetic dimension by using the cluster Gutzwiller mean-field method. Our results show that when the interexchange symmetry between the two species is broken, the regions of the super-counter-fluidity state in the phase diagram are dramatically shrunk whenever the on-site pair hopping term is turned on or off. Unexpectedly, the non-integer Mott phase and the molecular superfluid phase predicted in our previous work \citetext{Z. Lin et al., \textcolor{blue}{Phys. Rev. Lett. \textbf{125}, 245301 (2020)}}, can only exist in such a system that the pair hopping term is opened, and more importantly, its interexchange symmetry must be broken. Moreover, the demixing effect of the two-component bosonic system with synthetic pair hopping interaction has also been studied, and we find that an incompletely demixed state is formed in the system when the strength of the interspecies on-site repulsive interaction is sufficiently large.