Abstract
We explore repulsive Fermi polarons in one-dimensional harmonically trapped few-body mixtures of ultracold atoms using as a case example a 6Li-40K mixture. A characterization of these quasiparticle-like states, whose appearance is signaled in the impurity’s radiofrequency spectrum, is achieved by extracting their lifetime and residua. Increasing the number of 40K impurities leads to the occurrence of both single and multiple polarons that are entangled with their environment. An interaction-dependent broadening of the spectral lines is observed suggesting the presence of induced interactions. We propose the relative distance between the impurities as an adequate measure to detect induced interactions independently of the specifics of the atomic mixture, a result that we showcase by considering also a 6Li-173Yb system. This distance is further shown to be indicative of the generation of entanglement independently of the size of the bath (6Li) and the atomic species of the impurity. The generation of entanglement and the importance of induced interactions are revealed with an emphasis on the regime of intermediate interaction strengths.
Highlights
The properties and interactions of impurities immersed in a complex many-body (MB) environment represents a famous example of Landau’s quasiparticle theory [1]
We have simulated the corresponding experimental process of radiofrequency spectroscopy using different fermionic mixtures consisting of a single or two impurities coupled to a few-body Fermi sea
Analysing the obtained radiofrequency excitation spectrum it is shown that these impurities accumulate polaronic properties
Summary
The properties and interactions of impurities immersed in a complex many-body (MB) environment represents a famous example of Landau’s quasiparticle theory [1]. Very recently quasiparticle formation in fermionic systems associated with strong repulsive interactions have been experimentally realized first in the context of narrow [15] and subsequently for universal broad Feshbach resonances [16, 17] They have triggered a new era of theoretical investigations regarding the properties of repulsive Fermi polarons [18,19,20,21,22,23,24,25]. Inspecting the relative distance between the resulting quasiparticles, a quantity that can be probed experimentally via in-situ spin-resolved single-shot measurements [69], we observe its decrease which concordantly dictates the presence of induced interactions [70] The latter are found to be attractive despite the repulsive nature of the fundamental interactions in the system. In Appendix D we provide further details of our numerical findings presented in the main text
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