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Metastability and coherence of repulsive polarons in a strongly interacting Fermi mixture

Christoph Kohstall, Matteo Zaccanti, Michael Jag +5 more

arXiv:1112.0020NatureMay 1, 2012486 citations

Polarons in a strongly interacting Bose-Fermi mixture

Cheng-Hsun Wu, Ibon Santiago, Jee Woo Park +3 more

APSJun 1, 20120 citations

Repulsive polarons and itinerant ferromagnetism in strongly polarized Fermi gases

Pietro Massignan, Georg M. Bruun

arXiv:1102.0121The European Physical Journal DJul 27, 2011130 citations

Repulsive Fermi Polarons in a Resonant Mixture of Ultracold Li6 Atoms

Francesco Scazza, Giacomo Valtolina, Pietro Massignan +7 more

We employ radio-frequency spectroscopy to investigate a polarized spin mixture of ultracold ^{6}Li atoms close to a broad Feshbach scattering resonance. Focusing on the regime of strong repulsive interactions, we observe well-defined coherent quasiparticles even for unitarity-limited interactions. We characterize the many-body system by extracting the key properties of repulsive Fermi polarons: the energy E_{+}, the effective mass m^{*}, the residue Z, and the decay rate Γ. Above a critical interaction, E_{+} is found to exceed the Fermi energy of the bath, while m^{*} diverges and even turns negative, thereby indicating that the repulsive Fermi liquid state becomes energetically and thermodynamically unstable.We employ radio-frequency spectroscopy to investigate a polarized spin mixture of ultracold ^{6}Li atoms close to a broad Feshbach scattering resonance. Focusing on the regime of strong repulsive interactions, we observe well-defined coherent quasiparticles even for unitarity-limited interactions. We characterize the many-body system by extracting the key properties of repulsive Fermi polarons: the energy E_{+}, the effective mass m^{*}, the residue Z, and the decay rate Γ. Above a critical interaction, E_{+} is found to exceed the Fermi energy of the bath, while m^{*} diverges and even turns negative, thereby indicating that the repulsive Fermi liquid state becomes energetically and thermodynamically unstable.

arXiv:1609.09817Physical Review LettersFeb 21, 2017267 citations

Many Fermi polarons in a strongly interacting polarized mixture

Hiroyuki Tajima, Shun Uchino

An extremely polarized mixture of an ultracold Fermi gas is expected to reduce to a Fermi polaron system, which consists of a single impurity immersed in the Fermi sea of majority atoms. By developing a many-body T-matrix theory, we investigate spectral properties of the polarized mixture in experimentally relevant regimes in which the system of finite impurity concentration at nonzero temperature is concerned. We explicitly demonstrate presence of polaron physics in the polarized limit and discuss effects of many polarons in an intermediate regime in a selfconsistent manner. By analyzing the spectral function at finite impurity concentration, we extract the attractive and repulsive polaron energies. We find that a renormalization of majority atoms via an interaction with minority atoms is of significance to depict the many-polaron regime.An extremely polarized mixture of an ultracold Fermi gas is expected to reduce to a Fermi polaron system, which consists of a single impurity immersed in the Fermi sea of majority atoms. By developing a many-body T-matrix theory, we investigate spectral properties of the polarized mixture in experimentally relevant regimes in which the system of finite impurity concentration at nonzero temperature is concerned. We explicitly demonstrate presence of polaron physics in the polarized limit and discuss effects of many polarons in an intermediate regime in a selfconsistent manner. By analyzing the spectral function at finite impurity concentration, we extract the attractive and repulsive polaron energies. We find that a renormalization of majority atoms via an interaction with minority atoms is of significance to depict the many-polaron regime.

Jan 29, 20180 citations

Realization of repulsive polarons in the strongly correlated regime

Anonymous

Physical Review XAug 24, 20260 citations

Repulsive polarons in a strongly interacting Fermi mixture

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