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We discuss the superfluid wave function of an atomic Fermi gas, which can be measured in an atom shot noise correlation experiment. We note that it is qualitatively different in the BCS and Bose limits and on the basis of this we propose…

Other Condensed Matter · Physics 2007-05-23 Jorge Quintanilla

The non-relativistic $G_0 G$ formalism of BCS-BEC crossover at finite temperature is extended to relativistic fermion systems. The uncondensed pairs contribute a pseudogap to the fermion excitations. The theory recovers the BCS mean field…

High Energy Physics - Phenomenology · Physics 2008-11-26 Lianyi He , Pengfei Zhuang

We study resonantly-paired s-wave superfluidity in a degenerate gas of two species (hyperfine states labeled by $\uparrow,\downarrow$) of fermionic atoms when the numbers $N_{\uparrow}$ and $N_{\downarrow}$ of the two species are {\it…

Superconductivity · Physics 2009-11-11 Daniel E. Sheehy , Leo Radzihovsky

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

We investigate pairing fluctuation effects in a two band fermionic system, where a shallow band in the Bardeen--Cooper--Schrieffer--Bose--Einstein condensation (BCS-BEC) crossover regime is coupled with a weakly interacting deep band.…

Superconductivity · Physics 2020-01-23 Hiroyuki Tajima , Andrea Perali , Pierbiagio Pieri

We show that the long-distance behavior of the two-body density correlation functions and the Cooper-pair probability density of a balanced mixture of a two-component Fermi gas at $T = 0$, is universal along the BEC-BCS crossover. Our…

We study the pair-breaking effect of rotation on a cold Fermi gas in the BCS-BEC crossover region. In the framework of BCS theory, which is supposed to be qualitatively correct at zero temperature, we find that in a trap rotating around a…

Other Condensed Matter · Physics 2008-09-24 Michael Urban , Peter Schuck

Strongly correlated Fermi systems with pairing interactions become superfluid below a critical temperature $T_c$. The extent to which such pairing correlations alter the behavior of the liquid at temperatures $T > T_c$ is a subtle issue…

Quantum Gases · Physics 2020-08-12 Adam Richie-Halford , Joaquín E. Drut , Aurel Bulgac

We propose a method for simulating the behaviour of small clusters of particles that explicitly accounts for all mean-field and binary-correlation effects. Our approach leads to a set of variational equations that can be used to study both…

Other Condensed Matter · Physics 2009-11-11 J. N. Milstein , K. Burnett

The superfluidity and pairing phenomena in ultracold atomic Fermi gases have been of great interest in recent years, with multiple tunable parameters. Here we study the BCS-BEC crossover behavior of balanced two-component Fermi gases in a…

Quantum Gases · Physics 2020-05-20 Jibiao Wang , Leifeng Zhang , Yi Yu , Chaohong Lee , Qijin Chen

We present a new many body formalism for BCS-BEC crossover, which represents a modification of the BCS-Leggett ground state to include 4-fermion, and higher correlations. In the BEC regime, we show how our approach contains the…

Statistical Mechanics · Physics 2009-11-11 Shina Tan , K. Levin

By using the diffusion Monte Carlo method we calculate the one- and two-body density matrix of an interacting Fermi gas at T=0 in the BCS-BEC crossover. Results for the momentum distribution of the atoms, as obtained from the Fourier…

Other Condensed Matter · Physics 2009-11-11 G. E. Astrakharchik , J. Boronat , J. Casulleras , S. Giorgini

We present a pairing fluctuation theory which self-consistently incorporates finite momentum pair excitations in the context of BCS--Bose-Einstein condensation (BEC) crossover, and we apply this theory to high $T_c$ superconductors and…

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

We present an experimental study of the time of flight properties of a gas of ultra-cold fermions in the BEC-BCS crossover. Since interactions can be tuned by changing the value of the magnetic field, we are able to probe both non…

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 study the BCS-BEC crossover phenomenon of triplet exciton condensation using a half-filled bilayer Hubbard model. We calculate the dynamical spin structure factor and the exciton wave function on the phase boundary between the…

Strongly Correlated Electrons · Physics 2023-06-21 Hidemaro Suwa , Shang-Shun Zhang , Cristian D. Batista

A four-component Fermi gas in one dimension with a short-range four-body interaction is shown to exhibit a one-dimensional analog of the BCS-BEC crossover. Its low-energy physics is governed by a Tomonaga-Luttinger liquid with three spin…

Quantum Gases · Physics 2010-11-03 Yusuke Nishida , Dam T. Son

We address the phase of a highly polarized Fermi gas across a narrow Feshbach resonance starting from the problem of a single down spin fermion immersed in a Fermi sea of up spins. Both polaron and pairing states are considered using the…

Quantum Gases · Physics 2015-03-19 Ran Qi , Hui Zhai

We theoretically investigate the isothermal compressibility $\kappa_{T}$ in the normal state of an ultracold Fermi gas. Including pairing fluctuations, as well as preformed-pair formations, within the framework of the self-consistent…

Quantum Gases · Physics 2022-09-09 Daichi Kagamihara , Ryohei Sato , Koki Manabe , Hiroyuki Tajima , Yoji Ohashi

Superconductivity emerges from the spatial coherence of a macroscopic condensate of Cooper pairs. Increasingly strong binding and localization of electrons into these pairs compromises the condensate's phase stiffness, thereby limiting…

Strongly Correlated Electrons · Physics 2024-12-18 Niklas Witt , Yusuke Nomura , Sergey Brener , Ryotaro Arita , Alexander I. Lichtenstein , Tim O. Wehling