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The superfluidity and pairing phenomena in ultracold atomic Fermi gases have been of great interest in recent years, with multiple tunable parameters. Here we study the BCS-BEC crossover behavior of balanced two-component Fermi gases in a…

Quantum Gases · Physics 2020-05-20 Jibiao Wang , Leifeng Zhang , Yi Yu , Chaohong Lee , Qijin Chen

By using a well established 'ab initio' theoretical approach developed in the past to quantitatively study the superconductivity of condensed matter systems, which is based on the Kohn-Sham Density Functional theory, I study the superfluid…

Quantum Gases · Physics 2016-06-01 Francesco Ancilotto

In this letter a generalization of the BEC-BCS crossover theory to a multicomponent superfluid is presented by studying a three-species mixture of Fermi gas across two Feshbach resonances. At the BEC side of resonances, two kinds of…

Superconductivity · Physics 2013-05-29 Hui Zhai

The Leggett collective excitations for a two-band Fermi gas with s-wave pairing and Josephson interband coupling in the BCS-BEC crossover at finite temperatures are investigated within the Gaussian pair fluctuation approach.…

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

At finite temperature, the hydrodynamic collective modes of superfluid trapped Fermi gases are coupled to the motion of the normal component, which in the BCS limit behaves like a collisionless normal Fermi gas. The coupling between the…

Other Condensed Matter · Physics 2008-11-26 M. Urban

Collisionless damping of a condensate of cold Fermi atoms, whose scattering is controlled by a Feshbach resonance, is explored throughout the BCS and BEC regimes when small perturbations on its phase and amplitude modes are turned on to…

Quantum Gases · Physics 2012-05-07 Chi-Yong Lin , Da-Shin Lee , Ray J. Rivers

The pairing of fermionic atoms in a mixture of atomic fermion and boson gases at zero temperature is investigated. The attractive interaction between fermions, that can be induced by density fluctuations of the bosonic background, can give…

Quantum Gases · Physics 2015-05-30 F. Matera , A. Dellafiore

Trapped ultracold Fermi gases provide a system that can be tuned between the BCS and BEC regimes by means of a magnetic-field Feshbach resonance. Condensation of fermionic atom pairs in a $^{40}$K gas was demonstrated experimentally by a…

Strongly Correlated Electrons · Physics 2011-09-13 Qijin Chen , C. A. Regal , M. Greiner , D. S. Jin , K. Levin

Recent progress in the field of ultracold gases has allowed the creation of phase-segregated Bose-Fermi systems. We present a theoretical study of their collective excitations at zero temperature. As the fraction of fermion to boson…

Statistical Mechanics · Physics 2009-03-18 Bert Van Schaeybroeck , Achilleas Lazarides

We review our theoretical results about the sound propagation in two-dimensional (2D) systems of ultracold fermionic and bosonic atoms. In the superfluid phase, characterized by the spontaneous symmetry breaking of the $U(1)$ symmetry,…

Quantum Gases · Physics 2022-10-19 L. Salasnich , A. Cappellaro , K. Furutani , A. Tononi , G. Bighin

First and second sound speeds are calculated for a uniform superfluid gas of fermi atoms as a function of temperature, density and interaction strength. The second sound speed is of particular interest as it is a clear signal of a…

Superconductivity · Physics 2009-11-11 H. Heiselberg

We theoretically investigate superfluid properties of a two-band gas of $^{173}$Yb Fermi atoms with an orbital Feshbach resonance (OFR). To describe the BCS-BEC crossover region, we include superfluid fluctuations caused by inter-band and…

Quantum Gases · Physics 2021-05-27 Taro Kamihori , Daichi Kagamihara , Yoji Ohashi

In this paper we present a very general theoretical framework for addressing fermionic superfluids over the entire range of BCS to Bose Einstein condensation (BEC) crossover in the presence of population imbalance or spin polarization. Our…

Strongly Correlated Electrons · Physics 2011-09-13 Qijin Chen , Yan He , Chih-Chun Chien , K. Levin

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 address the thermodynamics, density profiles and superfluid density of trapped fermions undergoing BCS-BEC crossover, with and without population imbalance. Our approach represents a fully consistent treatment of "pseudogap effects",…

Strongly Correlated Electrons · Physics 2011-09-13 Yan He , Chih-Chun Chien , Qijin Chen , K. Levin

Superfluidity in an ultracold Fermi gas is usually associated with either a negative scattering length, or the presence of a two-body bound state. We show that none of these ingredients is necessary to achieve superfluidity. Using a narrow…

Statistical Mechanics · Physics 2009-11-11 Bout Marcelis , Servaas Kokkelmans

We consider atomic Fermi gases where Feshbach resonances can be used to continuously tune the system from weak to strong interaction regime, allowing to scan the whole BCS-BEC crossover. We show how a probing field transferring atoms out of…

Strongly Correlated Electrons · Physics 2009-11-10 J. Kinnunen , M. Rodriguez , P. Torma

We investigate an ultracold Bose-Fermi mixture with a Feshbach resonance between two hyperfine states of fermions. Using a functional integral method, we calculate collective modes associated with fermion-pairs and bosons in a superfluid…

Other Condensed Matter · Physics 2007-06-13 Hiroyuki Shibata , Nobuhiko Yokoshi , Susumu Kurihara

We study the transition to fermion pair superfluidity in a mixture of interacting bosonic and fermionic atoms. The fermion interaction induced by the bosons and the dynamical screening of the condensate phonons due to fermions are included…

Other Condensed Matter · Physics 2009-11-13 Tilman Enss , Wilhelm Zwerger

Atomic Fermi gases provide an ideal platform for studying the pairing and superfluid physics, using a Feshbach resonance between closed channel molecular states and open channel scattering states. Of particular interest is the strongly…