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We present an experimental study of the time of flight properties of a gas of ultra-cold fermions in the BEC-BCS crossover. Since interactions can be tuned by changing the value of the magnetic field, we are able to probe both non…

We systematically study relativistic two-species fermions with tunable attractive interactions and number-density asymmetry at zero temperature. In general, a Bardeen-Cooper-Schrieffer (BCS) - Bose-Einstein Condensation (BEC) - relativistic…

High Energy Physics - Phenomenology · Physics 2014-11-18 Hao Guo , Chih-Chun Chien , Yan He

The physics of the crossover between weak-coupling Bardeen-Cooper-Schrieffer (BCS) and strong-coupling Bose-Einstein-condensate (BEC) limits gives a unified framework of quantum bound (superfluid) states of interacting fermions. This…

We investigate the specific heat at constant volume $C_V$ in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an ultracold Fermi gas above the superfluid phase transition temperature $T_{\rm c}$.…

Quantum Gases · Physics 2016-02-03 Pieter van Wyk , Hiroyuki Tajima , Ryo Hanai , Yoji Ohashi

We review briefly the properties of a mixture of mutually interacting bosons (bound electron pairs) and itinerant fermions on a lattice (the boson-fermion model). The calculations of the superconducting phase transition temperature…

Superconductivity · Physics 2019-12-12 R. Micnas

Transition temperatures $T_{c}$ calculated using the BCS model electron-phonon interaction without any adjustable parameters agree with empirical values for quasi-2D cuprate superconductors. They follow from a two-dimensional gas of…

Superconductivity · Physics 2009-11-07 M. Casas , M. de Llano , A. Puente , A. Rigo , M. A. Solis

The BCS-BEC crossover is studied in a systematic way in the broken-symmetry phase between zero temperature and the critical temperature. This study bridges two regimes where quantum and thermal fluctuations are, respectively, important. The…

Superconductivity · Physics 2007-05-23 P. Pieri , L. Pisani , G. C. Strinati

This chapter presents the crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly-correlated pairs of fermions to the Bose-Einstein condensation (BEC) of diatomic molecules in the atomic Fermi gas. Our aim is to provide a…

Quantum Gases · Physics 2017-08-23 Meera M. Parish

We report on experimental studies on the collective behavior of a strongly interacting Fermi gas with tunable interactions and variable temperature. A scissors mode excitation in an elliptical trap is used to characterize the dynamics of…

Other Condensed Matter · Physics 2009-03-24 M. J. Wright , S. Riedl , A. Altmeyer , C. Kohstall , E. R. Sanchez Guajardo , J. Hecker Denschlag , R. Grimm

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

We review the BCS to Bose Einstein condensation (BEC) crossover scenario which is based on the well known crossover generalization of the BCS ground state wavefunction $\Psi_0$. While this ground state has been summarized extensively in the…

Superconductivity · Physics 2011-09-13 Qijin Chen , Jelena Stajic , Shina Tan , Kathryn Levin

Ultracold atomic Fermi gases present an opportunity to study strongly interacting Fermi systems in a controlled and uncomplicated setting. The ability to tune attractive interactions has led to the discovery of superfluidity in these…

Quantum Gases · Physics 2010-07-29 J. P. Gaebler , J. T. Stewart , T. E. Drake , D. S. Jin , A. Perali , P. Pieri , G. C. Strinati

We propose a simple bose-fermi model in two dimensions, with a coupling that converts pairs of opposite spin fermions into localized bosons and vice versa. We show that tracing out one of the degrees, either the bosons or fermions,…

Superconductivity · Physics 2020-10-23 Maciej M. Maśka , Nandini Trivedi

We experimentally determined various thermodynamic quantities of interacting two-component fermions at the zero-temperature limit from the Bardeen-Cooper-Schrieffer (BCS) region to the unitarity limit. The obtained results are very accurate…

We determine the size of the critical region of the superfluid transition in the BCS-BEC crossover of a three-dimensional fermion gas, using a renormalization-group approach to a bosonic theory of pairing fluctuations. For the unitary Fermi…

Quantum Gases · Physics 2016-03-08 T. Debelhoir , N. Dupuis

Fermi systems in the crossover regime between weakly coupled Bardeen-Cooper-Schrieffer (BCS) and strongly coupled Bose-Einstein-condensate (BEC) limits are among the most fascinating objects to study the behavior of an assembly of strongly…

We present a theoretical review of the recent progress in nonequilibrium BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover physics. As a paradigmatic example, we consider a strongly interacting driven-dissipative…

Quantum Gases · Physics 2025-03-07 Taira Kawamura , Yoji Ohashi

We investigate a mix-dimensional Fermi-Fermi mixture in which one species is confined in two-dimensional(2D) space while the other is free in three-dimensional space(3D). We determine the superfluid transition temperature $T_{c}$ for the…

Superconductivity · Physics 2015-05-27 Xiaosen Yang , Beibing Huang , Shaolong Wan

We investigate the uniform spin susceptibility $\chi_{\rm s}$ in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an ultracold Fermi gas. Including pairing fluctuations within the framework of an…

Quantum Gases · Physics 2015-10-16 H. Tajima , T. Kashimura , R. Hanai , R. Watanabe , Y. Ohashi

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