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We consider the normal state of a dense ultracold atomic Fermi gas in the presence of a Feshbach resonance. We study the BCS and the molecular instabilities and their interplay, within the framework of a recent many-body approach. We find…

Statistical Mechanics · Physics 2007-05-23 R. Combescot

We investigate the phase diagram and the BCS-BEC crossover of a homogeneous three-component ultracold Fermi gas with a U(3) invariant attractive interaction. We show that the system at sufficiently low temperatures exhibits population…

Quantum Gases · Physics 2010-12-16 Tomoki Ozawa , Gordon Baym

Quantum confinement is known to influence fermionic condensates, resulting in quantum-size oscillations of superfluid/superconducting properties. Here we show that the impact of quantum-size effects is even more dramatic. Under realistic…

Quantum Gases · Physics 2011-10-24 A. A. Shanenko , M. D. Croitoru , A. V. Vagov , V. M. Axt , A. Perali , F. M. Peeters

We report the long-time nonlinear dynamical evolution of ultracold atomic gases in the P-band of an optical lattice. A Bose-Einstein condensate (BEC) is fast and efficiently loaded into the Pband at zero quasi-momentum with a non-adiabatic…

Quantum Gases · Physics 2015-07-31 Dong Hu , Linxiao Niu , Baoguo Yang , Xuzong Chen , Biao Wu , Hongwei Xiong , Xiaoji Zhou

We study the critical temperature of the superfluid phase transition of strongly-interacting fermions in the crossover regime between a Bardeen-Cooper-Schrieffer (BCS) superconductor and a Bose-Einstein condensate (BEC) of dimers. To this…

Quantum Gases · Physics 2024-10-16 D. Eberz , M. Link , A. Kell , M. Breyer , K. Gao , M. Köhl

Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This is a direct consequence of…

A gas of interacting ultracold fermions can be tuned into a strongly interacting regime using a Feshbach resonance. Here we theoretically study quasiparticle transport in a system of two reservoirs of interacting ultracold fermions on the…

Quantum Gases · Physics 2016-09-19 Tibor Sekera , Christoph Bruder , Wolfgang Belzig

We study the finite temperature $T$ behavior of trapped Fermi gases as they undergo BCS-Bose Einstein condensation (BEC) crossover, in the presence of a population imbalance. Our results, in qualitative agreement with recent experiments,…

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

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 observe dramatic changes in the atomic momentum distribution of a Fermi gas in the region of the BCS-BEC crossover. We study the shape of the momentum distribution and the kinetic energy as a function of interaction strength. The…

Other Condensed Matter · Physics 2009-11-11 C. A. Regal , M. Greiner , S. Giorgini , M. Holland , D. S. Jin

One of the challenging goals in the studies of many-body physics with ultracold atoms is the creation of a topological $p_{x} + ip_{y}$ superfluid for identical fermions in two dimensions (2D). The expectations of reaching the critical…

Quantum Gases · Physics 2017-12-05 M. A. Caracanhas , F. Schreck , C. Morais Smith

We study theoretically the effect of the fermion and boson densities on the superconductivity transition critical temperature $(T_c)$ of a two dimensional electron gas (2DEG), where superconductivity is mediated by a Bose-Einstein…

Superconductivity · Physics 2014-10-15 E. D. Cherotchenko , T. Espinosa-Ortega , A. V. Nalitov , I. A. Shelykh , A. V. Kavokin

We discuss the evolution from BCS to Bose superfluidity for ultracold fermions in two-dimensions and in the presence of simultaneous spin-orbit and Zeeman fields. We analyze several thermodynamic properties to characterize different…

Quantum Gases · Physics 2012-06-22 Li Han , C. A. R. Sá de Melo

We investigate the formation of Bose-Einstein condensation and population imbalance in a three-component Fermi superfluid by increasing the U(3) invariant attractive interaction. We consider the system at zero temperature in three…

Quantum Gases · Physics 2011-04-06 Luca Salasnich

We have experimentally observed the dynamics of an antiferromagnetic sodium Bose-Einstein condensate (BEC) quenched through a quantum phase transition. Using an off-resonant microwave field coupling the F = 1 and F = 2 atomic hyperfine…

Quantum Gases · Physics 2011-11-08 E. M. Bookjans , A. Vinit , C. Raman

We analyze the phase diagram of superfluidity for two-species fermion mixtures from the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) limit as a function of scattering parameter, population imbalance and mass…

Superconductivity · Physics 2009-11-13 M. Iskin , C. A. R. Sa de Melo

We present an overview of our recent measurements on the crossover from a Bose-Einstein condensate of molecules to a Bardeen-Cooper-Schrieffer superfluid. The experiments are performed on a two-component spin-mixture of $^6$Li atoms, where…

Other Condensed Matter · Physics 2009-11-10 M. Bartenstein , A. Altmeyer , S. Riedl , S. Jochim , R. Geursen , C. Chin , J. Hecker Denschlag , R. Grimm

We describe the effects of disorder on the critical temperature of s-wave superfluids from the BCS to the BEC regime, with direct application to ultracold Fermi atoms. In the BCS regime the pair breaking and phase coherence temperature…

Quantum Gases · Physics 2009-04-28 Li Han , Carlos A. R. Sa de Melo

The superfluid phase diagrams of a two-dimensional cold polarized Fermi gas in the BCS-BEC crossover are systematically and analytically investigated. In the BCS-Leggett mean field theory, the transition from unpolarized superfluid phase to…

Superconductivity · Physics 2016-09-08 Lianyi He , Pengfei Zhuang

We present numerical calculations of the snake instability in a Fermi superfluid within the Bogoliubov-de Gennes theory of the BEC to BCS crossover using the random phase approximation complemented by time-dependent simulations. We examine…

Quantum Gases · Physics 2013-12-17 A. Cetoli , J. Brand , R. G. Scott , F. Dalfovo , L. P. Pitaevskii