Vortex bound states in polarized Fermi gases at unitarity

The study of quantized vortices is very important for our understanding of the superfluid properties of cold atoms. We briefly review current progress in this field, and then describe our recent work on the vortex structure of a strongly interacting spin-polarized Fermi gas. We analyze a singly-quantized vortex in a spin-polarized Fermi gas at unitarity, based on a mean-field approach. We find that a quantum phase transition occurs due to the occupation of the Andreev-like bound states at the vortex core. This may provide us with a new way to visualize the bound states by using phase-contrast imaging in cold-atom physics. Furthermore, we investigate the core size of vortices and find that the core expands gradually as the spin polarization increases.