我們藉由蒙地卡羅的計算方法討論兩種玻色子在方行晶格上有可能出現的量子相變。當我們增加對鄰近晶格的排斥力Mott insulator將變成solid，而且這樣的相變可由增加hopping的強度來達成，而這個相變是屬一階相變。並且我們觀察到supersolid變成superfluid同樣可由增加hopping的強度來達成，但此相變是屬二階相變。

We investigate the phase of two-species bosons in square lattice by the quantum Monte Carlo simulations. The Mott insulator phase becomes solid by increasing the nearest-neighbor repulsion. The phase changing can be driven by increasing the strength of hopping. It is found that there is a direct first-order transition. There is also the transition form the superfluid phase to the supersolid phase by increasing the nearest-neighbor repulsion. And the transition can be found when we drive the strength of hopping. We found that there is a second-order transition.

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