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For the Cooper/BCS model interaction in superconductors (SCs) it is shown: a) how BCS-Bose crossover picture transition temperatures Tc, defined self-consistently by both the gap and fermion-number equations, require unphysically large…

Superconductivity · Physics 2007-05-23 M. de Llano , F. J. Sevilla , M. A. Solis , J. J. Valencia

The functional renormalisation group is used for the BCS-BEC crossover in gases of ultracold fermionic atoms. In a simple truncation, we see how universality and an effective theory with composite bosonic di-atom states emerge. We obtain a…

Superconductivity · Physics 2009-11-13 S. Diehl , H. Gies , J. M. Pawlowski , C. Wetterich

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 investigate the BCS-BEC crossover in a bilayer system of fermionic dipoles at zero temperature using the fixed-node diffusion Monte Carlo technique. The dipoles are confined on two parallel planes separated by a distance $\lambda$ and…

Quantum Gases · Physics 2014-11-26 Natalia Matveeva , Stefano Giorgini

The Anderson-Bogoliubov branch of collective excitations in a condensed Fermi gas is treated using the effective bosonic action of Gaussian pair fluctuations. The spectra of collective excitations are treated for finite temperature and…

Quantum Gases · Physics 2019-12-09 S. N. Klimin , H. Kurkjian , J. Tempere

We observe a long-lived solitary wave in a superfluid Fermi gas of $^6$Li atoms after phase-imprinting. Tomographic imaging reveals the excitation to be a solitonic vortex, oriented transverse to the long axis of the cigar-shaped atom…

We study the thermodynamics of ideal Bose gas as well as the transport properties of non interacting bosons and fermions in a one dimensional quasi-periodic potential, namely Aubry-Andr\'e (AA) model at finite temperature. For bosons in…

Quantum Gases · Physics 2018-05-08 Nilanjan Roy , S. Sinha

By adopting a $T$-matrix based method within $G_0G$ approximation for the pair susceptibility, we studied the effects of pairing fluctuation on the BCS-BEC crossover in symmetric nuclear matter. The pairing fluctuation induces a pseudogap…

Nuclear Theory · Physics 2015-03-13 Xu-Guang Huang

We investigate the non-universal behavior of the BCS-BEC crossover model at the normal to superfluid transition. By using a finite temperature quantum field theoretical approach due to Nozieres and Schmitt-Rink and by making the effective…

Superconductivity · Physics 2007-05-23 L. M. Jensen

We explore the evolution of a ultracold quantum gas of interacting fermions crossing from a Bardeen-Cooper-Schrieffer (BCS) superfluidity to a Bose-Einstein condensation (BEC) of molecular bosons in the presence of a tunable-range…

Quantum Gases · Physics 2019-11-12 Davide Giambastiani , Michele Barsanti , Maria Luisa Chiofalo

The four-body problem for an interacting two-species Fermi gas is solved analytically in a confined quasi-one-dimensional geometry, where the two-body atom-atom scattering length $a_{aa}$ displays a confinement-induced resonance. We compute…

Statistical Mechanics · Physics 2007-05-23 C. Mora , A. Komnik , R. Egger , A. O. Gogolin

We perform a detailed study of the collective mode across the whole BEC-BCS crossover in fermionic gases at zero temperature, covering the whole range of energy beyond the linear regime. This is done on the basis of the dynamical BCS model.…

Other Condensed Matter · Physics 2014-11-17 R. Combescot , M. Yu. Kagan , S. Stringari

The present work aims at providing a systematic analysis of the current density versus momentum characteristics for a fermionic superfluid throughout the BCS-BEC crossover, even in the fully homogeneous case. At low temperatures, where…

Superconductivity · Physics 2024-03-20 Leonardo Pisani , Verdiana Piselli , Giancarlo Calvanese Strinati

Both the trapping geometry and the interatomic interaction strength of a dilute ultracold fermionic gas can be well controlled experimentally. When the interactions are tuned to strong attraction, Cooper pairing of neutral atoms takes place…

Other Condensed Matter · Physics 2007-05-23 J. Tempere , J. T. Devreese

We study the three-body problem for both fermionic and bosonic cold atom gases in a parabolic transverse trap of lengthscale $a_\perp$. For this quasi-one-dimensional (1D) problem, there is a two-body bound state (dimer) for any sign of the…

Statistical Mechanics · Physics 2007-05-23 C. Mora , R. Egger , A. O. Gogolin

We consider a system of fermions in the continuum case at zero temperature, in the strong-coupling limit of a short-range attraction when composite bosons form as bound-fermion pairs. We examine the density dependence of the size of the…

Superconductivity · Physics 2009-10-31 N. Andrenacci , P. Pieri , G. C. Strinati

We study the wave function $\phi^{(3)}$ of three identical bosons scattering at zero energy, zero total momentum, and zero orbital angular momentum in two dimensions, interacting via short-range potentials with a finite two-body scattering…

Quantum Gases · Physics 2026-01-29 Junjie Liang , Hongye Yu , Shina Tan

Strong evidence for pairing and superfluidity has recently been found in atomic Fermi gases at the BCS-BEC crossover both in collective modes and RF excitation energies. It is argued that the scale for the effective pairing gaps measured in…

Superconductivity · Physics 2009-11-10 H. Heiselberg

We calculate the phase diagram of identical fermions in a 2-dimensional (2D) lattice immersed in a 3D Bose-Einstein condensate (BEC). The fermions exchange density fluctuations in the BEC, which gives rise to an attractive induced…

Quantum Gases · Physics 2017-01-09 Jonatan Melkær Midtgaard , Zhigang Wu , G. M. Bruun

We study the effects of an external periodic potential on the critical velocity of a superfluid Fermi gas in the crossover between the Bardeen-Cooper-Schrieffer (BCS) phase and Bose-Einstein condensation (BEC). We numerically solve the…

Quantum Gases · Physics 2011-08-04 Gentaro Watanabe , Franco Dalfovo , Lev P. Pitaevskii , Sandro Stringari
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