Bose-Einstein condensation and critical behavior of two-component bosonic gases

作者：Ceccarelli Giacomo^*; Nespolo Jacopo; Pelissetto Andrea; Vicari Ettore

来源：Physical Review A, 2015, 92(4): 043613.

DOI：10.1103/PhysRevA.92.043613

We study Bose-Einstein condensation (BEC) in three-dimensional two-component bosonic gases, characterizing the universal behaviors of the critical modes arising at the BEC transitions. For this purpose, we use field-theoretical (FT) renormalization-group (RG) methods and perform mean-field and numerical calculations. The FT RG analysis is based on the Landau-Ginzburg-Wilson Phi(4) theory with two complex scalar fields which has the same symmetry as the bosonic system. In particular, for identical bosons with exchange Z(2) symmetry, coupled by effective density-density interactions, the global symmetry is Z(2, e) circle times U(1) circle times U(1). At the BEC transition, it may break into Z(2, e) circle times Z(2) circle times Z(2) when both components condense simultaneously, or to U(1) circle times Z(2) when only one component condenses. This implies different universality classes for the corresponding critical behaviors. Numerical simulations of the two-component Bose-Hubbard model in the hard-core limit support the RG prediction: when both components condense simultaneously, the critical behavior is controlled by a decoupled XY fixed point, with unusual slowly decaying scaling corrections arising from the onsite interspecies interaction.

• 出版日期2015-10-19