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We determine the size of the critical region of the superfluid transition in the BCS-BEC crossover of a three-dimensional fermion gas, using a renormalization-group approach to a bosonic theory of pairing fluctuations. For the unitary Fermi…

Quantum Gases · Physics 2016-03-08 T. Debelhoir , N. Dupuis

A gas of interacting ultracold fermions can be tuned into a strongly interacting regime using a Feshbach resonance. Here we theoretically study quasiparticle transport in a system of two reservoirs of interacting ultracold fermions on the…

Quantum Gases · Physics 2016-09-19 Tibor Sekera , Christoph Bruder , Wolfgang Belzig

We measure excitation spectra of an ultracold gas of fermionic $^{40}$K atoms in the BCS-BEC crossover regime. The measurements are performed with a novel spectroscopy that employs a small modulation of the B-field close to a Feshbach…

Statistical Mechanics · Physics 2011-08-12 Markus Greiner , Cindy A. Regal , Deborah S. Jin

We show that the atom-molecule mixture formed in a degenerate atomic Fermi gas with interspecies repulsion near a Feshbach resonance, constitutes a peculiar system where the atomic component is almost non-degenerate but quantum degeneracy…

Statistical Mechanics · Physics 2009-11-10 S. J. J. M. F. Kokkelmans , G. V. Shlyapnikov , C. Salomon

We present a numerical study of the one-dimensional BCS-BEC crossover of a spin-imbalanced Fermi gas. The crossover is described by the Bose-Fermi resonance model in a real space representation. Our main interest is in the behavior of the…

Quantum Gases · Physics 2013-05-29 F. Heidrich-Meisner , A. E. Feiguin , U. Schollwoeck , W. Zwerger

We address theoretically the puzzling discontinuity of the radial quadrupole mode frequency observed in a trapped Fermi gas across the BEC-BCS crossover. We apply the scaling transformation to a two-channel model of a resonant Fermi…

Quantum Gases · Physics 2025-06-02 Sergueï V. Andreev

We present an overview of recent developments in species-imbalanced ("polarized") Feshbach-resonant Fermi gases. We summarize the current status of thermodynamics of these systems in terms of a phase diagram as a function of the Feshbach…

Quantum Gases · Physics 2010-06-25 Leo Radzihovsky , Daniel E. Sheehy

Due to the vast growth of the many-body level density with excitation energy, its smoothed form is of central relevance for spectral and thermodynamic properties of interacting quantum systems. We compute the cumulative of this level…

Quantum Gases · Physics 2019-06-26 Quirin Hummel , Juan Diego Urbina , Klaus Richter

We evaluate the frequencies of collective modes and the anisotropic expansion rate of a harmonically trapped Fermi superfluid at varying coupling strengths across a Feshbach resonance driving a BCS-BEC crossover. The equations of motion for…

Statistical Mechanics · Physics 2007-05-23 Hui Hu , A. Minguzzi , Xia-Ji Liu , M. P. Tosi

By including the effect of a trap with characteristic energy given by the Fermi temperature $T_F$ in a two-body two-channel model for Feshbach resonances, we reproduce the experimental closed-channel fraction $Z$ across the BEC-BCS…

Quantum Gases · Physics 2020-09-23 Eloisa Cuestas , José I. Robledo , Ana P. Majtey

We introduce the Global Spin Model to study the static and dynamic properties of the ultracold fermionic gas near the broad Feshbach resonance. We show that the problem of molecular production, in a single-mode approximation, is reduced to…

Other Condensed Matter · Physics 2009-02-13 Deqiang Sun , Ar. Abanov , V. L. Pokrovsky

We investigate the zero-temperature properties of a dilute two-component Fermi gas with attractive interspecies interaction in the BCS-BEC crossover. We build an efficient parametrization of the energy per particle based on Monte Carlo data…

Soft Condensed Matter · Physics 2009-11-10 N. Manini , L. Salasnich

We theoretically study a possible new pairing mechanism for a two-dimensional population imbalanced Fermi gas with short-range repulsive interactions which can be realized on the upper branch of a Feshbach resonance. We use a…

Quantum Gases · Physics 2013-05-29 Shao-Jian Jiang , Xiao-Lu Yu , W. M. Liu

We report on the observation of triatomic Efimov resonances in an ultracold gas of cesium atoms. Exploiting the wide tunability of interactions resulting from three broad Feshbach resonances in the same spin channel, we measure…

The physics of atomic quantum gases is currently taking advantage of a powerful tool, the possibility to fully adjust the interaction strength between atoms using a magnetically controlled Feshbach resonance. For fermions with two internal…

Quantum Gases · Physics 2015-05-27 Yvan Castin , Félix Werner

We have analyzed a single vortex at T=0 in a 3D superfluid atomic Fermi gas across a Feshbach resonance. On the BCS side, the order parameter varies on two scales: $k_{F}^{-1}$ and the coherence length $\xi$, while only variation on the…

Superconductivity · Physics 2011-09-28 R. Sensarma , M. Randeria , T. L. Ho

This report adresses topics and questions of common interest in the fields of ultra-cold gases and nuclear physics in the context of the BCS-BEC crossover. The BCS-BEC crossover has recently been realized experimentally, and essentially in…

We study the universal relations and normal-phase thermodynamics of a two-component ultracold Fermi gas with coexisting $s$- and $p$-wave interactions. Due to the orthogonality of two-body wave functions of different scattering channels,…

Quantum Gases · Physics 2018-03-20 Fang Qin , Xiaoling Cui , Wei Yi

We analyze the divergent zero-point energy of a dilute and ultracold gas of atoms in D spatial dimensions. For bosonic atoms we explicitly show how to regularize this divergent contribution, which appears in the Gaussian fluctuations of the…

Quantum Gases · Physics 2016-07-19 L. Salasnich , F. Toigo

We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the…

Statistical Mechanics · Physics 2009-11-10 J. E. Williams , N. Nygaard , C. W. Clark