Comment on “Phase separation in a two-species Bose mixture”

Abstract

In an article in 2007, Mishra et al. [Phys. Rev. A 76, 013604 (2007)] investigated the two-component Bose-Hubbard model using the numerical density-matrix renormalization-group procedure. In the regime of interspecies repulsion ${U}^{ab}$ larger than the intraspecies repulsion $U$, they found a transition from a uniform miscible phase to phase separation occurring at a finite value of $U$, e.g., at around $U=1.3$ for $\ensuremath{\Delta}={U}^{ab}/U=1.05$ and ${\ensuremath{\rho}}_{a}={\ensuremath{\rho}}_{b}=1/2$. In this Comment, we show that this result is not correct, and in fact, the two-component Bose-Hubbard model is unstable to phase separation for any ${U}^{ab}>U>0$.