Induced interactions in a superfluid Bose-Fermi mixture
Induced interactions in a superfluid Bose-Fermi mixture
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DOI：
10.1103/physreva.91.041605
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发表时间：
2015-02
影响因子：
2.9
通讯作者：
J. Kinnunen;G. Bruun
中科院分区：
文献类型：
--
作者：
J. Kinnunen;G. Bruun
我们分析了玻色-爱因斯坦凝聚体（BEC）与超流体双组分费米气体在整个BCS-BEC交叉中的混合。利用准粒子随机相近似结合Beliaev理论分别描述费米超流体和BEC，我们证明了费米气体的单粒子和集体激发会引起玻色子之间的诱导相互作用，这种相互作用随动量和频率的强烈变化。它在费米超流体的声模处发散，导致了一个尖锐的避免交叉特征，并在BEC的激发谱中产生了相应的相互作用能移的符号变化。此外，准粒子在费米超流体中的激发导致了BEC中激发的阻尼。除了研究诱导相互作用本身，这些突出的效应可以用来系统地探测强相互作用的费米气体。
We analyse a Bose-Einstein condensate (BEC) mixed with a superfluid two-component Fermi gas in the whole BCS-BEC cross-over. Using a quasiparticle random phase approximation combined with Beliaev theory to describe the Fermi superfluid and the BEC respectively, we show that the single particle and collective excitations of the Fermi gas give rise to an induced interaction between the bosons, which varies strongly with momentum and frequency. It diverges at the sound mode of the Fermi superfluid, resulting in a sharp avoided crossing feature and a corresponding sign change of the interaction energy shift in the excitation spectrum of the BEC. In addition, the excitation of quasiparticles in the Fermi superfluid leads to damping of the excitations in the BEC. Besides studying induced interactions themselves, these prominent effects can be used to systematically probe the strongly interacting Fermi gas.