We investigate the metastable repulsive branch of a mobile impurity coupled to a degenerate Fermi gas via short-range interactions. We show that the quasiparticle lifetime of this repulsive Fermi polaron can be experimentally probed by driving Rabi oscillations between weakly and strongly interacting impurity states. Using a time-dependent variational approach, we find that we can accurately model the impurity Rabi oscillations that were recently measured for repulsive Fermi polarons in both two and three dimensions. Crucially, our theoretical description does not include relaxation processes to the lower-lying attractive branch. Thus, the theory-experiment agreement demonstrates that the quasiparticle lifetime is dominated by many-body dephasing within the upper repulsive branch rather than by relaxation from the upper branch itself. Our findings shed light on recent experimental observations of persistent repulsive correlations, and have important consequences for the nature and stability of the strongly repulsive Fermi gas.

中文翻译：

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排斥费米极化子的准粒子寿命

我们研究了通过近程相互作用与简并费米气体耦合的移动杂质的亚稳态排斥支。我们表明，该排斥费米极化子的准粒子寿命可以通过驱动弱相互作用和强相互作用杂质状态之间的拉比振荡进行实验探测。使用时间相关的变分方法，我们发现我们可以准确地建模最近在二维和三维两个方面针对斥力费米极化子测得的杂质拉比振荡。至关重要的是，我们的理论描述不包括对低层有吸引力分支的松弛过程。因此，理论-实验协议表明，准粒子寿命主要由上排斥分支内的多体移相控制，而不是由上分支本身的弛豫控制。