title：Polarons in a Fermi superfluid

报告人：易为 教授
中国科技大学量子信息国家重点实验室
时间：2015年4月15日（星期三） 下午4:00
地点：理论物理所报告厅

Abstract: We study a new type of Fermi polaron induced by an impurity interacting with an ultracold Fermi superfluid. Due to the three-component nature of the system, the polaron can become trimer-like with a non-universal energy spectrum. We identify multiple avoided crossings between impurity- and trimer-like solutions in both the attractive and the repulsive polaron spectra. The widths of avoided crossings gradually increase as the Fermi superfluid undergoes a crossover from the BCS side towards the BEC side, which suggests instabilities towards three-body losses. Such losses can be reduced for interaction potentials with small effective ranges. Using the second-order perturbation theory, we then demonstrate that the mean-field evaluation of the fermion-impurity interaction energy is inadequate even for small fermion-impurity scattering lengths, due to the essential effects of Fermi superfluid and short-range physics in such a system.