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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

We determine the superfluid transition temperature $T_c$ and related finite temperature phase diagrams for the entire BCS-Bose Einstein condensation crossover in a homogeneous mixture of $^{6}$Li and $^{40}$K atoms with population…

Other Condensed Matter · Physics 2013-05-29 Hao Guo , Chih-Chun Chien , Qijin Chen , Yan He , K. Levin

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

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

We theoretically investigate excitation properties in the pseudogap regime of a trapped Fermi gas. Using a combined $T$-matrix theory with the local density approximation, we calculate strong-coupling corrections to single-particle local…

Quantum Gases · Physics 2015-05-28 Shunji Tsuchiya , Ryota Watanabe , Yoji Ohashi

Understanding the formation of Cooper pairs and the resulting thermodynamic properties of a low-dimensional Fermi gas is an important area of research, elucidating our understanding of high temperature superconductors. In lower dimensions…

Quantum Gases · Physics 2016-02-16 Brendan C. Mulkerin , Kristian Fenech , Paul Dyke , Chris J. Vale , Xia-Ji Liu , Hui Hu

We present a theory for the low-temperature properties of a resonantly interacting Fermi mixture in a trap, that goes beyond the local-density approximation. The theory corresponds essentially to a Landau-Ginzburg-like approach that…

Quantum Gases · Physics 2015-05-27 J. M. Diederix , H. T. C. Stoof

We develop a theory of superconductivity (or superfluidity) based on condensed fermion quartets focusing on the dilute spin-$\frac{1}{2}$ systems at zero temperature. In the spirit of the Bardeen--Cooper--Schrieffer ansatz, a variational…

Superconductivity · Physics 2026-05-29 Qiao-Ru Xu , Congjun Wu

We present an ab initio determination of spin responses of the unitary Fermi gas, based on finite temperature quantum Monte Carlo calculations and the Kubo linear-response formalism. We determine the temperature dependence of the spin…

We theoretically investigate strong-coupling effects on specific heat at constant volume $C_{\rm V}$ in a superfluid Fermi gas with a tunable interaction associated with Feshbach resonance. Including fluctuations of the superfluid order…

Quantum Gases · Physics 2019-05-22 Daisuke Inotani , Pieter van Wyk , Yoji Ohashi

Interacting Fermi systems in the strongly correlated regime play a fundamental role in many areas of physics and are of particular interest to the condensed matter community. Though weakly inter- acting fermions are understood, strongly…

Quantum Gases · Physics 2016-07-27 Brendan C. Mulkerin , Xia-Ji Liu , Hui Hu

We investigate the effects of topological order on the transition temperature, $T_c$, and response functions in fermionic superfluids with Rashba spin-orbit coupling and a transverse Zeeman field in three dimensions. Our calculations,…

Quantum Gases · Physics 2016-05-10 Brandon M. Anderson , Chien-Te Wu , Rufus Boyack , K. Levin

High order perturbation theory corrections to the superfluid transition temperature in a weakly interacting Fermi gas with repulsive interaction are calculated. This involves calculating the contributions of third and fourth order diagrams…

Superconductivity · Physics 2009-10-31 D. V. Efremov , M. S. Mar'enko , M. A. Baranov , M. Yu. Kagan

We show that the minimal mean-field theory to use for calculating the pair distribution functions $g_{\sigma\sigma'}(\vec{r},\vec{r}\,')$ of a spatially homogeneous, unpolarized spin-1/2 superfluid Fermi gas is not the ordinary static BCS…

Quantum Gases · Physics 2026-04-22 Yvan Castin

We investigate the effects of pairing fluctuations in fermionic superfluids/superconductors where pairing occurs among three species (colors) of fermions. Such color superfluids/superconductors can be realized in three-component atomic…

Nuclear Theory · Physics 2013-09-19 Jinyi Pang , Jincheng Wang , Lianyi He

The strongly attractive Fermi gas in the BCS-BEC crossover is efficiently described in terms of coupled fermions and fermion pairs, or molecules. We compute the spectral functions of both fermions and pairs in the normal state near the…

Quantum Gases · Physics 2024-03-01 Tilman Enss

We investigate magnetic properties and strong coupling corrections in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an ultracold Fermi gas. Within the framework of an extended $T$-matrix theory, we…

Quantum Gases · Physics 2015-10-16 Hiroyuki Tajima , Ryo Hanai , Ryota Watanabe , Yoji Ohashi

We investigate superfluid properties of a one-component Fermi gas with a uniaxially anisotropic $p$-wave pairing interaction, $U_x>U_y=U_z$ (where $U_i$ ($i=x,y,z)$ is a $p_i$-wave pairing interaction). This type of interaction is…

Quantum Gases · Physics 2016-01-20 Daisuke Inotani , Yoji Ohashi

Fermionic superfluidity requires the formation of pairs. The actual size of these fermion pairs varies by orders of magnitude from the femtometer scale in neutron stars and nuclei to the micrometer range in conventional superconductors.…

Superconductivity · Physics 2008-08-14 Christian H. Schunck , Yong-il Shin , Andre Schirotzek , Wolfgang Ketterle

Thermal fluctuations of quasiparticle number are included making use of the secondary Bogolyubov's transformation, which turns quasiparticles operators into modified-quasiparticle ones. This restores the unitarity relation for the…

Nuclear Theory · Physics 2017-08-23 Nguyen Dinh Dang