Trap-imbalanced fermion mixtures

Abstract

We analyze the ground state phases of two-component ($\sigma \equiv \lbrace \uparrow, \downarrow \rbrace$) population- and mass-balanced ($N_\uparrow = N_\downarrow$ and $m_\uparrow = m_\downarrow$) but trap-imbalanced ($\omega_\uparrow \ne \omega_\downarrow$) fermion mixtures as a function of interaction strength from the weak attraction Bardeen-Cooper-Schrieffer (BCS) to the strong attraction Bose-Einstein condensation (BEC) limit. In the BCS limit, we find that the unpolarized superfluid (UPS) fermions exist away from the central core of the trapping potentials, and are surrounded by partially polarized normal (P$\sigma$PN) fermions. As the interactions increase towards unitarity, we find that the central P$\sigma$PN core first transitions to a UPS, and then expands towards the edges until the entire mixture becomes a UPS in the BEC limit.