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 Delta = U-ab/U = 1.05 and rho(a) = 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.