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We experimentally investigate the first-order correlation function of a trapped Fermi gas in the two-dimensional BEC-BCS crossover. We observe a transition to a low-temperature superfluid phase with algebraically decaying correlations. We…

Quantum Gases · Physics 2015-07-03 P. A. Murthy , I. Boettcher , L. Bayha , M. Holzmann , D. Kedar , M. Neidig , M. G. Ries , A. N. Wenz , G. Zürn , S. Jochim

We present a new many body formalism for BCS-BEC crossover, which represents a modification of the BCS-Leggett ground state to include 4-fermion, and higher correlations. In the BEC regime, we show how our approach contains the…

Statistical Mechanics · Physics 2009-11-11 Shina Tan , K. Levin

We in this paper investigate the phase diagram associated with the BCS-BEC crossover of a three-component ultracold superfluid-Fermi-gas of different chemical-potentials and equal masses in two dimensions. The gap order parameter and number…

Quantum Gases · Physics 2015-06-04 Jiajia Du , Junjun Liang , J. -Q. Liang

We discuss an integrable model of interacting Fermions in one dimension, that allows an exact description of the crossover from a BCS- to a Bose-like superfluid. This model bridges the Gaudin-Yang model of attractive spin 1/2 Fermions to…

Statistical Mechanics · Physics 2007-05-23 J. N. Fuchs , A. Recati , W. Zwerger

We analyse a Bose-Einstein condensate (BEC) mixed with a superfluid two-component Fermi gas in the whole BCS-BEC cross-over. Using a quasiparticle random phase approximation combined with Beliaev theory to describe the Fermi superfluid and…

Quantum Gases · Physics 2015-05-07 J. J. Kinnunen , G. M. Bruun

We investigate the superfluid phase transition and effects of mass imbalance in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an cold Fermi gas. We point out that the Gaussian fluctuation theory…

Quantum Gases · Physics 2013-07-11 Ryo Hanai , Takashi Kashimura , Ryota Watanabe , Daisuke Inotani , Yoji Ohashi

We calculate, for the first time, the state-dependent pairing gap of a finite nucleus (120Sn) diagonalizing the bare nucleon-nucleon potential (Argonne v14) in a Hartree-Fock basis (with effective k-mass m_k eqult to 0.7 m), within the…

Nuclear Theory · Physics 2009-11-10 F. Barranco , R. A. Broglia , G. Colo' , E. Vigezzi , P. F. Bortignon

The equilibrium properties of a weakly interacting atomic Bose gas across the Berezinskii-Kosterlitz-Thouless (BKT) and Bose-Einstein condensation (BEC) phase transitions are numerically investigated through a dimensionality crossover from…

Quantum Gases · Physics 2024-12-13 Nick Keepfer , I-Kang Liu , Franco Dalfovo , Nick Proukakis

We study a finite-time thermodynamic refrigeration cycle realized numerically in three-dimensional, weakly interacting Bose-Einstein condensates (BECs). The setup consists of three spatially separated condensates -- system, piston, and…

The Bardeen-Cooper-Schrieffer to Bose-Einstein condensate (BCS to BEC) crossover problem is solved for stationary grey solitons via the Boguliubov-de Gennes equations at zero temperature. These \emph{crossover solitons} exhibit a localized…

Quantum Gases · Physics 2015-05-05 Andrea Spuntarelli , Lincoln D. Carr , Pierbiagio Pieri , Giancarlo C. Strinati

Multiple phases occurring in a Bose gas with finite-range interaction are investigated. In the vicinity of the onset of Bose-Einstein condensation (BEC) the chemical potential and the pressure show a van-der-Waals like behavior indicating a…

Quantum Gases · Physics 2013-05-24 M. Männel , K. Morawetz , P. Lipavský

We theoretically investigate single particle excitations in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein-Condensation) crossover regime of an ultracold Fermi gas. Including strong pairing fluctuations within a $T$-matrix…

Quantum Gases · Physics 2017-05-31 Miki Ota , Hiroyuki Tajima , Ryo Hanai , Daisuke Inotani , Yoji Ohashi

We study a two-component Bose gas with a symmetric spin-orbit coupling, and find that two atoms can form a bound state with any intra- or inter-species scattering length. Consequently, in the dilute limit, the Bardeen-Cooper-Shrieffer (BCS)…

Quantum Gases · Physics 2017-10-02 Dekun Luo , Lan Yin

We theoretically investigate the recent photoemission-type experiment on $^{40}$K Fermi gases done by JILA group. Including pairing fluctuations within a strong-coupling $T$-matrix theory, as well as effects of a harmonic trap within the…

Quantum Gases · Physics 2016-11-18 Ryota Watanabe , Shunji Tsuchiya , Yoji Ohashi

Using a formalism based on the two-body S-matrix we study two-dimensional Bose and Fermi gases with both attractive and repulsive interactions. Approximate analytic expressions, valid at weak coupling and beyond, are developed and applied…

Quantum Gases · Physics 2017-07-18 Guilherme Franca , Andre LeClair , Joshua Squires

We have demonstrated that it is possible to access a crossover scenario starting with a weak coupling (BCS) d-wave superconductor to a strongly coupled Bose-Einstein condensate (BEC) phase as the exchange interaction is tuned in a two…

Strongly Correlated Electrons · Physics 2015-06-15 Subrat Kumar Das , Ayan Khan , Saurabh Basu

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

We derive a generalized Gross-Pitaevskii density-functional equation appropriate to study the Bose-Einstein condensate (BEC) of dimers formed of singlet spin-half Fermi pairs in the BEC-unitarity crossover while the dimer-dimer scattering…

Quantum Gases · Physics 2015-05-14 S. K. Adhikari , Hong Lu , Han Pu

We develop a simple analytical model based on a variational method to explain the properties of trapped cylindrically symmetric Bose-Einstein condensates (BEC) of varying degrees of anisotropy well into regimes of effective one dimension…

Statistical Mechanics · Physics 2009-11-07 Kunal Das

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