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We explore the possibility that fermionic dark matter undergoes a BCS transition to form a superfluid. This requires an attractive interaction between fermions and we describe a possible source of this interaction induced by torsion. We…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-13 Stephon Alexander , Sam Cormack

We study the zero temperature ground state of a two-dimensional atomic Fermi gas with chemical potential and population imbalance in the mean-field approximation. All calculations are performed in terms of the two-body binding energy…

Other Condensed Matter · Physics 2015-05-30 Heron Caldas , A. L. Mota , R. L. S. Farias , L. A. Souza

We consider a mixture of two neutral cold Fermi gases with repulsive interactions. We show that in some region of the parameter space of the system the effective attraction between fermions of the same type can appear due to the exchange of…

Quantum Gases · Physics 2013-08-01 T. Espinosa-Ortega , O. Kyriienko , I. A. Shelykh

This paper gives a survey of a diagrammatic approach for fermionic pairing fluctuations, which are relevant to the BCS-BEC crossover realized with ultracold Fermi gases. Emphasis will be given to the physical intuition about the relevant…

Quantum Gases · Physics 2010-11-29 G. C. Strinati

We consider inter- and intra-species pairing interactions in an asymmetrical Fermi system. Using equation of motion method, we obtain coupled mean-field equations for superfluid gap functions and population densities. We construct a phase…

Superconductivity · Physics 2014-04-24 Renyuan Liao , Khandker F. Quader

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 discuss correlations between particles of different momentum in a superfluid fermi gas, accessible through noise measurements of absorption images of the expanded gas. We include two elements missing from the simplest treatment, based on…

Statistical Mechanics · Physics 2009-11-11 Austen Lamacraft

We study a gas of fermions undergoing a wide resonance s-wave BCS-BEC crossover, in the BEC regime at zero temperature. We calculate the chemical potential and the speed of sound of this Bose-condensed gas, as well as the condensate…

Superconductivity · Physics 2009-11-11 J. Levinsen , V. Gurarie

We develop the hydrodynamic theory of Fermi superfluids in the presence of a periodic potential. The relevant parameters governing the propagation of sound (compressibility and effective mass) are calculated in the weakly interacting BCS…

Soft Condensed Matter · Physics 2016-08-31 L. P. Pitaevskii , S. Stringari , G. Orso

We analyze the BCS-BEC crossover transition of a balanced two component mixture of fermions interacting via a finite range potential, within a mean field approach. For the analysis we consider three finite range potentials cases describing…

We study the coherence properties of a trapped two-component gas of fermionic atoms below the BCS critical temperature. We propose an optical method to investigate the Cooper-pair coherence across different regions of the superfluid.…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Gh. -S. Paraoanu , M. Rodriguez , P. Torma

The BCS-to-BEC crossover, as well as the nature of Cooper pairs, in a superconducting and Fermi superfluid medium is studied from the exact ground state wavefunction of the reduced BCS Hamiltonian. As the strength of the interaction…

Superconductivity · Physics 2009-11-11 Gerardo Ortiz , Jorge Dukelsky

We derive a nonlinear differential equation for the gap parameter of a superfluid Fermi system by performing a suitable coarse graining of the Bogoliubov-de Gennes (BdG) equations throughout the BCS-BEC crossover, with the aim of replacing…

Superconductivity · Physics 2014-02-21 S. Simonucci , G. C. Strinati

The entanglement entropy of two gapless non-interacting fermion subsystems is computed approximately in a way that avoids the introduction of replicas and a geometric interpretation of the reduced density matrix. We exploit the similarity…

Statistical Mechanics · Physics 2013-05-29 G. C. Levine , B. A. Friedman

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 derive semiclassical transport equations for a trapped atomic Fermi gas in the BCS phase at temperatures between zero and the superfluid transition temperature. These equations interpolate between the two well-known limiting cases of…

Other Condensed Matter · Physics 2023-10-24 M. Urban , P. Schuck

In this paper we show how to redress a shortcoming of the path integral scheme for fermionic superfluids and superconductors. This approach is built around a simultaneous calculation of electrodynamics and thermodynamics. An important sum…

Quantum Gases · Physics 2016-05-18 Brandon M. Anderson , Rufus Boyack , Chien-Te Wu , K. Levin

New calculation reveals that E is constant in a thin layer across the Fermi surface, befitting the definition of energy gap parameter, Delta varies dramatically. The BCS self-consistent equation has a simple and exact solution, showing that…

Superconductivity · Physics 2007-05-23 Xue Heng Zheng

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 present a theory of a two-component atomic Fermi gas with tunable attractive contact interactions on a spherical shell going through the Bardeen-Cooper-Schrieffer (BCS) - Bose Einstein condensation (BEC) crossover, inspired by the…

Quantum Gases · Physics 2022-04-01 Yan He , Hao Guo , Chih-Chun Chien