Dynamics of a Repulsive Fermi-Fermi Mixture

There is a growing interest in repulsively interacting Fermi gas mixtures, which could enable investigations of correlated quantum systems. As repulsive interactions in Fermi gases near a Feshbach resonance arise from the presence of a loosely bound molecular state, they are always associated with decay into bosonic molecules [1]. The interplay between repulsion and decay has made the realization and understanding of repulsive Fermi systems challenging [2,3]. We investigate the dynamics of a strongly interacting $^{40}$K-$^{6}$Li Fermi-Fermi mixture on the repulsive side of an interspecies Feshbach resonance. For this purpose, we employ magnetic field ramps, RF spectroscopy, in-situ and time-of-flight imaging. Close to the resonance, we observe a static behavior of the K atomic population, redistribution of the Li density away from the K cloud and an absence of the interaction-induced shifts in the dissociation RF spectra in the strongly interacting repulsive regime. In spite of a strong initial atom loss, our results suggest that repulsive interactions are crucial for the dynamics of our system.\\[4pt][1] D. Pekker, et al., {\sl Phys. Rev. Lett.} {\bf 106}, 050402 (2011).\\[0pt][2] G. Jo, et al., {\sl Science} {\bf 325}, 5947 (2009).\\[0pt][3] C. Sanner et al., arXiv:1108.2017