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We consider collective excitations in the superfluid state of Fermi condensed charged gases. The dispersion and damping of collective excitations at nonzero temperatures are examined, and the coexistence and interaction of different…

Quantum Gases · Physics 2023-06-26 S. N. Klimin , J. Tempere , T. Repplinger , H. Kurkjian

The zero-temperature properties of a dilute two-component Fermi gas in the BCS-BEC crossover are investigated. On the basis of a generalization of the Hylleraas-Undheim method, we construct rigorous upper bounds to the collective…

Other Condensed Matter · Physics 2009-11-11 Yeong E. Kim , Alexander L. Zubarev

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

The two-species cold atomic Fermi gas with attractive short-range interactions in two spatial dimensions undergoes a Bardeen-Cooper-Schrieffer (BCS) to a Bose-Einstein Condensate (BEC) crossover as a function of $\ln (k_F a)$, where $a$ is…

Quantum Gases · Physics 2026-02-27 S. Ramachandran , S. Jensen , Y. Alhassid

A new mechanism is proposed to explain the puzzling damping of collective excitations, which was recently observed in the experiments of strongly interacting Fermi gases below the superfluid critical temperature on the fermionic (BCS) side…

Quantum Gases · Physics 2011-03-01 Zixu Zhang , W. Vincent Liu

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

Thermodynamic properties of an ultracold Fermi gas in a harmonic trap are calculated within a local density approximation, using a conserving many-body formalism for the BCS to BEC crossover problem, which has been developed by Haussmann et…

Statistical Mechanics · Physics 2009-11-13 R. Haussmann , W. Zwerger

We present a systematic theoretical study of the BCS-BEC crossover problem in three-dimensional atomic Fermi gases at zero temperature with a spherical spin-orbit coupling which can be generated by a synthetic non-Abelian gauge field…

Quantum Gases · Physics 2012-07-13 Lianyi He , Xu-Guang Huang

Ultracold atomic gases are a powerful tool to experimentally study strongly correlated quantum many-body systems. In particular, ultracold Fermi gases with tunable interactions have allowed to realize the famous BEC-BCS crossover from a…

We theoretically investigate the isothermal compressibility $\kappa_{T}$ in the normal state of an ultracold Fermi gas. Including pairing fluctuations, as well as preformed-pair formations, within the framework of the self-consistent…

Quantum Gases · Physics 2022-09-09 Daichi Kagamihara , Ryohei Sato , Koki Manabe , Hiroyuki Tajima , Yoji Ohashi

The BCS-BEC crossover realized experimentally with ultra-cold Fermi gases may be considered as one of the important scientific achievements occurred during the last several years. The flexibility for operating on these systems on the…

Quantum Gases · Physics 2024-03-20 Giancarlo Calvanese Strinati

We investigate strong pairing fluctuations and effects of a harmonic trap in the superfluid phase of an ultracold Fermi gas. Including amplitude and phase fluctuations of the inhomogeneous superfluid order parameter $\Delta(r)$ in a trap…

Quantum Gases · Physics 2015-06-11 Ryota Watanabe , Shunji Tsuchiya , Yoji Ohashi

Trapped ultra-cold atom experiments provide a unique opportunity to understand Bose-Fermi superfluid mixtures occurring in contrasting areas of physics. At present there are several atom-trap experiments that could potentially explore this…

Quantum Gases · Physics 2011-01-31 B. Ramachandhran , S. G. Bhongale , H. Pu

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

The pairing and superfluid phenomena in a two-component Fermi gas can be strongly affected by the population and mass imbalances. Here we present phase diagrams of atomic Fermi gases as they undergo BCS--Bose-Einstein condensation (BEC)…

Quantum Gases · Physics 2014-04-24 Jibiao Wang , Hao Guo , Qijin Chen

We report the experimental measurement of the equation of state of a two-dimensional Fermi gas with attractive s-wave interactions throughout the crossover from a weakly coupled Fermi gas to a Bose gas of tightly bound dimers as the…

Quantum Gases · Physics 2016-02-02 I. Boettcher , L. Bayha , D. Kedar , P. A. Murthy , M. Neidig , M. G. Ries , A. N. Wenz , G. Zürn , S. Jochim , T. Enss

The crossover from a BEC (Bose-Einstein condensation) to a BCS (Bardeen-Cooper-Schrieffer) superfluid in dilute gases of ultracold Fermi atoms creates an ideal environment to enrich our knowledge of strongly correlated many-body systems.…

Quantum Gases · Physics 2010-08-25 Hui Hu , Xia-Ji Liu , Peter D. Drummond , Hui Dong

We study the superfluid state of atomic Fermi gases using a BCS-BEC crossover theory. Our approach emphasizes non-condensed fermion pairs which strongly hybridize with their (Feshbach-induced) molecular boson counterparts. These pairs lead…

Soft Condensed Matter · Physics 2011-09-13 Jelena Stajic , J. N. Milstein , Qijin Chen , M. L. Chiofalo , M. J. Holland , K. Levin

The BCS-BEC crossover from strongly overlapping Cooper pairs to non-overlapping composite bosons in the strong coupling limit has been a long-standing issue of interacting many-body fermion systems. Recently, FeSe semimetal with hole and…

Superconductivity · Physics 2023-08-21 Y. Mizukami , M. Haze , O. Tanaka , K. Matsuura , D. Sano , J. Böker , I. Eremin , S. Kasahara , Y. Matsuda , T. Shibauchi

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