Mass-imbalance-induced structures of binary atomic mixtures in box potentials

摘要

We consider the ground states of binary atomic boson-boson and fermion-fermion mixtures confined in one-dimensional box potentials by simulating the systems using few-body models with δ-function interactions and many-body models with density-density interactions. For boson-boson mixtures with strong interspecies repulsion, both models show sandwiched structures in the presence of mass imbalance but not in the equal-mass case. The structural difference between equal-mass and mass-imbalanced systems is due to the minimization of the interaction energy and the kinetic energies from the density distortion at the hard walls and at the phaseseparation interface. The mass imbalance adjusts the kinetic energies and causes the lighter species to avoid the hard walls. For fermion-fermion mixtures, few-body simulations show mass-imbalance-induced structural changes in the strong-repulsion regime, while many-body simulations show two-chunk phase separation due to the strong bulk kinetic energy. For equal-mass mixtures with strong interspecies repulsion, the few-body and many-body models predict different structures because of the different treatments of kinetic and interaction energies.