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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

Preparation of molecular quantum gas promises novel applications including quantum control of chemical reactions, precision measurements, quantum simulation and quantum information processing. Experimental preparation of colder and denser…

Atomic Physics · Physics 2021-04-29 Zhendong Zhang , Liangchao Chen , Kaixuan Yao , Cheng Chin

We determine the effects on the BCS-BEC crossover of the energy dependence of the effective two-body interaction, which at low energies is determined by the effective range. To describe interactions with an effective range of either sign,…

Superconductivity · Physics 2008-11-26 L. M. Jensen , H. M. Nilsen , Gentaro Watanabe

We extend our previous investigations of fermionic condensation in broad Feshbach resonances by using the two-channel model developed for narrow Feshbach resonances. We investigate two crossovers: the BCS-BEC crossover by changing the…

Quantum Gases · Physics 2012-11-19 Luca Salasnich

The condensation of paired fermions into superfluid states changes progressively depending on the coupling strength. At the midpoint of the crossover between Bardeen--Cooper--Schrieffer (BCS) weak-coupling and Bose--Einstein condensate…

The crossover from weak coupling Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) of tightly bound pairs, as a function of the attractive interaction in Fermi systems, has long been of interest to theoretical…

Quantum Gases · Physics 2014-04-09 Mohit Randeria , Edward Taylor

A recent Bose-Einstein condensation (BEC) model of several cuprate superconductors is based on bosonic Cooper pairs (CPs) moving in 3D with a quadratic energy-momentum (dispersion) relation. The 3D BEC condensate-fraction vs. temperature…

Superconductivity · Physics 2009-11-11 M. de Llano , J. J. Valencia

We prove two equilibrium properties of a system of interacting atoms in three or higher dimensional continuous space. (i) If the particles interact via pair potentials of a nonnegative Fourier transform, their self-organization into…

Mathematical Physics · Physics 2023-05-31 Andras Suto

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

We derive a theory for Bose condensation in nonequilibrium steady states of bosonic quantum gases that are coupled both to a thermal heat bath and to a pumped reservoir (or gain medium), while suffering from loss. Such a scenario describes…

Statistical Mechanics · Physics 2018-07-04 Daniel Vorberg , Roland Ketzmerick , André Eckardt

We study a confined mixture of bosons and fermions in the regime of quantal degeneracy, with particular attention to the effects of the interactions on the kinetic energy of the fermionic component. We are able to explore a wide region of…

Condensed Matter · Physics 2015-06-25 L. Vichi , M. Amoruso , A. Minguzzi , S. Stringari , M. P. Tosi

The boson-fermion atomic bound states (composite fermion) and their roles for the phase structures are studied in a bose-fermi mixed condensate of atomic gas in finite temperature and density. The two-body scattering equation is formulated…

Other Condensed Matter · Physics 2009-11-10 H. Yabu , Y. Takayama , T. Suzuki , P. Schuck

We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of $^6$Li atoms in the BCS-BEC crossover regime we identify a critical…

Statistical Mechanics · Physics 2009-11-13 Yong-il Shin , André Schirotzek , Christian H. Schunck , Wolfgang Ketterle

We consider a very asymmetric system of Fermions with an interaction characterized by a positive scattering length only. The minority atoms pair and form a BEC of dimers, while the surplus fermions interact only indirectly through the…

Statistical Mechanics · Physics 2009-05-15 Aurel Bulgac , Sukjin Yoon

The BCS-BEC crossover within the two-dimensional attractive Hubbard model is studied by using the Cellular Dynamical Mean-Field Theory both in the normal and superconducting ground states. Short-range spatial correlations incorporated in…

Strongly Correlated Electrons · Physics 2009-11-11 B. Kyung , A. Georges , A. -M. S. Tremblay

In this paper we present a very general theoretical framework for addressing fermionic superfluids over the entire range of BCS to Bose Einstein condensation (BEC) crossover in the presence of population imbalance or spin polarization. Our…

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

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

The pair correlation function of an expanding gas is investigated with an emphasis on the BEC-BCS crossover of a superfluid Fermi gas at zero temperature. At unitarity quantum Monte Carlo simulations reveal the occurrence of a sizable…

Soft Condensed Matter · Physics 2009-11-11 C. Lobo , I. Carusotto , S. Giorgini , A. Recati , S. Stringari

Low-lying nuclear states of Sm isotopes are studied in the framework of a collective Hamiltonian based on covariant energy density functional theory. Pairing correlation are treated by both BCS and Bogoliubov methods. It is found that the…

Nuclear Theory · Physics 2015-06-18 J. Xiang , Z. P. Li , J. M. Yao , W. H. Long , P. Ring , J. Meng

We investigate the ground state of a few-body Bose-Fermi mixture in a one-dimensional harmonic trap with varying interaction strengths and mass ratio. A bunching-antibunching crossover of the bosonic species for increasing interspecies'…

Quantum Gases · Physics 2018-08-03 J. Chen , J. M. Schurer , P. Schmelcher