Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2103.03625 · Physical Review A

Stability and breakdown of Fermi polarons in a strongly interacting Fermi-Bose mixture

Isabella Fritsche, Cosetta Baroni, Erich Dobler, Emil Kirilov, Bo Huang, Rudolf Grimm, Georg M. Bruun, Pietro Massignan

Published May 17, 2021• 53 citations
arXivHTMLPDF

Abstract

The authors experimentally prepare and investigate the properties of a strongly interacting imbalanced mixture of bosonic 41K impurities immersed in a Fermi sea of ultracold 6Li atoms. Two configurations have been explored: a thermal regime described by the Fermi polaron picture and a partially Bose-Einstein-condensed regime described by coexisting Fermi and Bose polarons.

DOI
10.1103/physreva.103.053314

Related papers

Strongly interacting isotopic Bose-Fermi mixture immersed in a Fermi sea

Cheng-Hsun Wu, Ibon Santiago, Jee Woo Park +2 more

We have created a triply quantum-degenerate mixture of bosonic $^{41}\mathrm{K}$ and two fermionic species $^{40}\mathrm{K}$ and $^{6}\mathrm{Li}$. The boson is shown to be an efficient coolant for the two fermions, spurring hopes for the observation of fermionic superfluids with imbalanced masses. We observe multiple heteronuclear Feshbach resonances, in particular a wide $s$-wave resonance for the combination $^{41}\mathrm{K}$-$^{40}\mathrm{K}$, opening up studies of strongly interacting isotopic Bose-Fermi mixtures. For large imbalance in the local densities of different species, we enter the polaronic regime of dressed impurities immersed in a bosonic or fermionic bath.

arXiv:1103.4630•Physical Review A•Jul 13, 2011•113 citations

Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms

Ariel Sommer, Cheng-Hsun Wu, Martin W. Zwierlein +1 more

We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities’ rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea.

APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts•Jun 1, 2009•0 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.

•Jan 29, 2018•0 citations

Realization of a Strongly Interacting Bose-Fermi Mixture from a Two-Component Fermi Gas

Yong-il Shin, André Schirotzek, Christian H. Schunck +1 more

We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of 6Li atoms in the BCS-BEC crossover regime, we identify a critical interaction strength, beyond which all minority atoms pair up with majority atoms and form a Bose condensate. This is the regime where the system can be effectively described as a boson-fermion mixture. We determine the dimer-fermion and dimer-dimer scattering lengths and beyond-mean-field contributions. Our study realizes a gedanken experiment of bosons immersed in a Fermi sea of one of their constituents, revealing the composite nature of the bosons.

arXiv:0805.0623•Physical Review Letters•Aug 14, 2008•102 citations

Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms

André Schirotzek, Cheng-Hsun Wu, Ariel Sommer +1 more

We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities' rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea.

arXiv:0902.3021•Physical Review Letters•Jun 8, 2009•635 citations

Imbalanced Fermi gases and dilute interacting Polarons

Christophe Mora

Recent experiments on imbalanced Fermi gases in ultracold atomic systems have raised interest in the physics of an impurity immersed in a Fermi sea, the so-called Fermi polaron. In particular, the internal energy of a Fermi polaron gives the threshold for a fully polarized normal phase. When partially polarized, the normal phase can be described quantitatively as a Fermi liquid of dilute polarons. We discuss a simple theory devised to describe dilute Fermi-polaron ensembles and show that an exact formula can be obtained for the dominant interaction between polarons. It is expressed solely in terms of a single polaron parameter. The physics of this interaction is identified as a signature of the Pauli exclusion principle. The comparison of this theory with experimental results shows a remarkable agreement up to the vicinity of the transition to the superfluid phase.

•Jul 14, 2010•0 citations
The authors experimentally prepare and investigate the properties of a strongly interacting imbalanced mixture of bosonic 41K impurities immersed in a Fermi sea of ultracold 6Li atoms. Two configurations have been explored: a thermal regime described by the Fermi polaron picture and a partially Bose-Einstein-condensed regime described by coexisting Fermi and Bose polarons.
We have created a triply quantum-degenerate mixture of bosonic 41K^{41}\mathrm{K}41K and two fermionic species 40K^{40}\mathrm{K}40K and 6Li^{6}\mathrm{Li}6Li. The boson is shown to be an efficient coolant for the two fermions, spurring hopes for the observation of fermionic superfluids with imbalanced masses. We observe multiple heteronuclear Feshbach resonances, in particular a wide sss-wave resonance for the combination 41K^{41}\mathrm{K}41K-40K^{40}\mathrm{K}40K, opening up studies of strongly interacting isotopic Bose-Fermi mixtures. For large imbalance in the local densities of different species, we enter the polaronic regime of dressed impurities immersed in a bosonic or fermionic bath.
We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities’ rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea.
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.
We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of 6Li atoms in the BCS-BEC crossover regime, we identify a critical interaction strength, beyond which all minority atoms pair up with majority atoms and form a Bose condensate. This is the regime where the system can be effectively described as a boson-fermion mixture. We determine the dimer-fermion and dimer-dimer scattering lengths and beyond-mean-field contributions. Our study realizes a gedanken experiment of bosons immersed in a Fermi sea of one of their constituents, revealing the composite nature of the bosons.
We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities' rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea.
Recent experiments on imbalanced Fermi gases in ultracold atomic systems have raised interest in the physics of an impurity immersed in a Fermi sea, the so-called Fermi polaron. In particular, the internal energy of a Fermi polaron gives the threshold for a fully polarized normal phase. When partially polarized, the normal phase can be described quantitatively as a Fermi liquid of dilute polarons. We discuss a simple theory devised to describe dilute Fermi-polaron ensembles and show that an exact formula can be obtained for the dominant interaction between polarons. It is expressed solely in terms of a single polaron parameter. The physics of this interaction is identified as a signature of the Pauli exclusion principle. The comparison of this theory with experimental results shows a remarkable agreement up to the vicinity of the transition to the superfluid phase.