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We investigate strong pairing fluctuations and effects of a harmonic trap in the superfluid phase of an ultracold Fermi gas. Including amplitude and phase fluctuations of the inhomogeneous superfluid order parameter $\Delta(r)$ in a trap…

Quantum Gases · Physics 2015-06-11 Ryota Watanabe , Shunji Tsuchiya , Yoji Ohashi

This report adresses topics and questions of common interest in the fields of ultra-cold gases and nuclear physics in the context of the BCS-BEC crossover. The BCS-BEC crossover has recently been realized experimentally, and essentially in…

We analyze the zero temperature phase diagram for an asymmetric two-component Fermi gas as a function of mass anisotropy and population imbalance. We identify regions corresponding to normal, or uniform/non-uniform superfluid phases, and…

Superconductivity · Physics 2007-05-23 M. Iskin , C. A. R. Sa de Melo

We experimentally investigate the first-order correlation function of a trapped Fermi gas in the two-dimensional BEC-BCS crossover. We observe a transition to a low-temperature superfluid phase with algebraically decaying correlations. We…

Quantum Gases · Physics 2015-07-03 P. A. Murthy , I. Boettcher , L. Bayha , M. Holzmann , D. Kedar , M. Neidig , M. G. Ries , A. N. Wenz , G. Zürn , S. Jochim

The method of functional renormalization is applied to the theoretical investigation of ultracold quantum gases. Flow equations are derived for a Bose gas with approximately pointlike interaction, for a Fermi gas with two (hyperfine) spin…

Quantum Gases · Physics 2015-05-14 S. Floerchinger

We investigate strong-coupling effects on normal state properties of an ultracold Fermi gas. Within the framework of $T$-matrix approximation in terms of pairing fluctuations, we calculate the single-particle density of states (DOS), as…

Quantum Gases · Physics 2013-05-29 Shunji Tsuchiya , Ryota Watanabe , Yoji Ohashi

The Quantum Monte Carlo method for spin 1/2 fermions at finite temperature is formulated for dilute systems with an s-wave interaction. The motivation and the formalism are discussed along with descriptions of the algorithm and various…

Statistical Mechanics · Physics 2009-02-05 Aurel Bulgac , Joaquin E. Drut , Piotr Magierski

This article is written as a Lecture given in the 2006 Varenna Summer School on "Ultracold Fermi Gases". Here we present a review of BCS--Bose Einstein condensation (BEC) crossover theory with emphasis on finite temperature effects. We…

Strongly Correlated Electrons · Physics 2011-09-13 K. Levin , Qijin Chen

We study finite-temperature properties of a two-dimensional superfluid made of ultracold alkali-metal atoms in the BCS-BEC crossover. We investigate the region below the critical temperature $T_{BKT}$ of the Berezinskii-Kosterlitz-Thouless…

Quantum Gases · Physics 2013-11-20 L. Salasnich , P. A. Marchetti , F. Toigo

We investigate within a self-consistent theory the molecular instabilities arising in the normal state of a homogeneous degenerate Fermi gas, covering the whole BEC-BCS crossover. These are the standard instability for molecular formation,…

Other Condensed Matter · Physics 2010-07-23 R. Combescot , X. Leyronas , M. Yu. Kagan

We investigate unconventional superfluidity in a gas of Fermi atoms with an anisotropic p-wave Feshbach resonance. Including the p-wave Feshbach resonance as well as the associated three kinds of quasi-molecules with finite orbital angular…

Other Condensed Matter · Physics 2009-11-10 Yoji Ohashi

We examine the effect of the trapping potential on the critical temperature, $T_C$, for the BCS transition to a superfluid state in trapped atomic gases of fermions. $T_C$ for an arbitrary power law trap is calculated in the Thomas-Fermi…

Superconductivity · Physics 2009-11-07 C. P. Search , H. Pu , W. Zhang , B. P. Anderson , P. Meystre

We investigate the fluctuation effect of the di-fermion field in the crossover from Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) in a relativistic superfluid. We work within the boson-fermion model obeying a…

High Energy Physics - Phenomenology · Physics 2008-11-26 Jian Deng , Jin-cheng Wang , Qun Wang

By adopting a $T$-matrix-based method within the $G_0G$ approximation for the pair susceptibility, we study the effects of the pairing fluctuation on the three-dimensional spin-orbit coupled Fermi gases at finite temperature. The critical…

Quantum Gases · Physics 2013-06-11 Lianyi He , Xu-Guang Huang , Hui Hu , Xia-Ji Liu

The physics of quantum degenerate Fermi gases in uniform as well as in harmonically trapped configurations is reviewed from a theoretical perspective. Emphasis is given to the effect of interactions which play a crucial role, bringing the…

Other Condensed Matter · Physics 2009-11-13 Stefano Giorgini , Lev P. Pitaevskii , Sandro Stringari

The influence of thermal fluctuations on fermion pairing is investigated using a semiclassical treatment of fluctuations. When the average pairing gaps along with those differing by one standard deviation are used, the characteristic…

Nuclear Theory · Physics 2018-12-27 M. A. A. Mamun , C. Constantinou , M. Prakash

We study pseudogap behaviors of ultracold Fermi gases in the BCS-BEC crossover region. We calculate the density of states (DOS), as well as the single-particle spectral weight, above the superfluid transition temperature $T_{\rm c}$…

Quantum Gases · Physics 2015-05-13 S. Tsuchiya , R. Watanabe , Y. Ohashi

We discuss the possibility of a quantum phase transition in ultra-cold spin-polarized Fermi gases which exhibit a p-wave Feshbach resonance. We show that when fermionic atoms form a condensate that can be externally tuned between the BCS…

Strongly Correlated Electrons · Physics 2009-11-11 S. S. Botelho , C. A. R. Sa de Melo

The proximity effect, which arises at the interface between two fermionic superfluids with different critical temperatures, is examined with a non-local (integral) equation whose kernel contains information about the size of Cooper pairs…

Superconductivity · Physics 2018-10-17 V. Piselli , S. Simonucci , G. Calvanese Strinati

The role of fluctuations is enhanced in lower dimensionality systems: in a two dimensions off-diagonal long-range order is destroyed by the fluctuations at any finite temperature, drastically modifying the critical properties with respect…

Quantum Gases · Physics 2016-03-11 G Bighin , L Salasnich