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Ultracold atomic gases are a powerful tool to experimentally study strongly correlated quantum many-body systems. In particular, ultracold Fermi gases with tunable interactions have allowed to realize the famous BEC-BCS crossover from a…

We extend a recently introduced separable interaction for the unitary trapped Fermi gas to all values of the scattering length. We derive closed expressions for the interaction matrix elements and the two-particle eigenvectors and…

Quantum Gases · Physics 2012-06-27 C. N. Gilbreth , Y. Alhassid

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

We use a BCS-type variational wavefunction to study attractively-interacting quasi one-dimensional (1D) fermionic atomic gases, motivated by cold-atom experiments that access the 1D regime using an anisotropic harmonic trapping potential…

Quantum Gases · Physics 2015-07-16 Stephen Kudla , Dominique M. Gautreau , Daniel E. Sheehy

In the [BCS] paper the theory of superconductivity was developed for the BCS model, in which the (instantaneous) interaction is only between fermions of opposite momentum and spin. Such model was analyzed by variational methods, finding…

Strongly Correlated Electrons · Physics 2015-06-25 Vieri Mastropietro

We investigate the quantum and thermal phase diagram of fermionic polar molecules loaded in a bilayer trapping potential with perpendicular dipole moment. We use both a BCS theory approach that is most realiable at weak-coupling and a…

Quantum Gases · Physics 2012-01-13 N. T. Zinner , B. Wunsch , D. Pekker , D. -W. Wang

The (mean field based) BCS theory is considered one of the most successful theories in condensed matter physics. It is justified in ordinary metal superconductors the coherence length $\xi$ is large, with two important features: the order…

Superconductivity · Physics 2018-01-22 Qijin Chen

We study the critical temperature of a superconductive material in a weak external electric potential via a linear approximation of the BCS functional. We reproduce a similar result as in [Frank, Hainzl, Seiringer, Solovej, 2016] using the…

Mathematical Physics · Physics 2018-09-25 Rupert L. Frank , Christian Hainzl

This paper addresses the transition from the normal to the superfluid state in strongly correlated two dimensional fermionic superconductors and Fermi gases. We arrive at the Berezinskii-Kosterlitz-Thouless (BKT) temperature…

Superconductivity · Physics 2020-07-13 Xiaoyu Wang , Qijin Chen , K. Levin

This review is written at the time of the twentieth anniversary of the discovery of high temperature superconductors, which, nearly coincides with the important discovery of the superfluid phases of ultracold trapped fermionic atoms. We…

Superconductivity · Physics 2011-09-13 Qijin Chen , Jelena Stajic , K. Levin

We study Gaussian fluctuations of the zero-temperature attractive Fermi gas in the 2D BCS-BEC crossover showing that they are crucial to get a reliable equation of state in the BEC regime of composite bosons, bound states of fermionic…

Quantum Gases · Physics 2015-01-27 L. Salasnich , F. Toigo

Possible Bose-Einstein condensation of molecules and Bardeen-Cooper-Schrieffer (BCS) condensation of Cooper pairs of atoms in an ultracold Fermi gas of atoms with a repulsive two-body interaction are studied by using the path integral…

Other Condensed Matter · Physics 2007-05-23 Fuxiang Han , Hailing Li , Minghao Lei , E Wu

We present a self-consistent theory for the thermodynamics of the BCS-BEC crossover in the normal and superfluid phase which is both conserving and gapless. It is based on the variational many-body formalism developed by Luttinger and Ward…

Statistical Mechanics · Physics 2009-02-05 R. Haussmann , W. Rantner , S. Cerrito , W. Zwerger

Pairing effects manifests themselves in many aspects in nuclear systems ranging from finite nuclei to nuclear matter and compact stars. Although with some specific features for nuclear systems, the mechanism of pairing between nucleons in…

Nuclear Theory · Physics 2024-02-07 Xiang-Xiang Sun , Shan-Gui Zhou

We introduce an alternative expression for the ground state wave function of the fermionic Tonks-Girardeau gas. Our wave function is constructed based on the occupation numbers and natural orbitals of the one-body density matrix. We…

Using the Gaussian pair fluctuation theory, we investigate quantum fluctuations of a strongly interacting two-dimensional chiral \textit{p}-wave Fermi superfluid at the transition from a Bose-Einstein condensate (BEC) to a topologically…

Quantum Gases · Physics 2018-12-12 Hui Hu , Brendan C. Mulkerin , Lianyi He , Jia Wang , Xia-Ji Liu

We study a dilute gas of interacting fermions at temperature $T=0$ and chemical potential $\mu \in \mathbb{R}$. The particles are trapped by an external potential, and they interact via a microscopic attractive two-body potential with a…

Mathematical Physics · Physics 2023-01-10 Andrea Calignano , Michele Correggi

The Bose-Einstein condensation (BEC) temperature $T_{c}$ of Cooper pairs (CPs) created from a very general interfermion interaction is determined for a {\it linear}, as well as the usual quadratic, energy {\it vs}% center-of-mass momentum…

Superconductivity · Physics 2017-08-23 F. J. Sevilla , M. Grether , M. Fortes , M. de Llano , O. Rojo , M. A. Solís , A. A. Valladares

We present a general method for the high-temperature expansion of the self-energy of interacting particles. Though the method is valid for fermions and bosons, we illustrate it for spin one half fermions interacting via a zero range…

Quantum Gases · Physics 2015-11-18 Mingyuan Sun , Xavier Leyronas

We theoretically investigate strong-coupling properties of an ultracold Fermi gas with an orbital Feshbach resonance (OFR). Including tunable pairing interaction associated with an OFR within the framework of the strong-coupling theory…

Quantum Gases · Physics 2018-05-09 Soumita Mondal , Daisuke Inotani , Yoji Ohashi