BCS BEC crossover: From high temperature superconductors to ultracold superfluids

  title={BCS BEC crossover: From high temperature superconductors to ultracold superfluids},
  author={Qijin Chen and Jelena Stajic and Shina Tan and Kathryn Levin},
  journal={Physics Reports},
Abstract We review the BCS to Bose–Einstein condensation (BEC) crossover scenario which is based on the well known crossover generalization of the BCS ground state wavefunction Ψ 0 . While this ground state has been summarized extensively in the literature, this Review is devoted to less widely discussed issues: understanding the effects of finite temperature, primarily below T c , in a manner consistent with Ψ 0 . Our emphasis is on the intersection of two important problems: high T c… Expand
Applying BCS–BEC crossover theory to high-temperature superconductors and ultracold atomic Fermi gases (Review Article)
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 ofExpand
BCS–BEC crossover in cold atomic and in nuclear systems
Abstract We review the BCS (Bardeen–Cooper–Schrieffer)–BEC (Bose–Einstein condensation) crossover phenomenon discussed in an ultracold Fermi atomic gas and a neutron superfluid in the low-densityExpand
Comparison of different pairing fluctuation approaches to BCS–BEC crossover
Abstract The subject of BCS–Bose–Einstein condensation (BEC) crossover is particularly exciting because of its realization in ultracold atomic Fermi gases and its possible relevance to highExpand
What Can Ultracold Fermi Gases Teach Us About High Tc Superconductors and Vice Versa
Studies of superfluidity in ultracold trapped Fermi gases are attracting physicists from a wide range of sub-disciplines including nuclear, condensed matter and particle physics. The excitement inExpand
BCS-BEC Crossover and the Unitary Fermi Gas
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, hasExpand
Pairing Fluctuations, the BCS–BEC Crossover and Strong Disorder in Superconductors
The mean field theory due to Bardeen, Cooper, and Schrieffer (BCS) provides the conceptual foundation of our understanding of superconductivity, but many examples over the last few decades haveExpand
Experimental Realization of the BCS-BEC Crossover with a Fermi Gas of Atoms
Abstract Ultracold atomic gases have proven to be remarkable model systems for exploring quantum mechanical phenomena. Experimental work on gases of fermionic atoms in particular has seen astoundingExpand
Tuning across the BCS-BEC crossover in the multiband superconductor Fe1+ySexTe1−x: An angle-resolved photoemission study
This work realizes the BCS-BEC crossover in a nearly compensated semimetal, Fe1+ySexTe1−x, by tuning the Fermi energy εF via chemical doping, which permits us to systematically change Δ/εF from 0.16 to 0.50. Expand
The BCS–BEC crossover: From ultra-cold Fermi gases to nuclear systems
Abstract This report addresses topics and questions of common interest in the fields of ultra-cold gases and nuclear physics in the context of the BCS–BEC crossover. By this crossover, the phenomenaExpand
Electron pairing and evidence of a BCS–BEC crossover in d-wave superconductors
Abstract We have demonstrated that it is possible to access a crossover scenario starting with a weak coupling (BCS) d-wave superconductor to a strongly coupled Bose–Einstein condensate (BEC) phaseExpand


Generalization of BCS theory to short coherence length superconductors: A BCS--Bose-Einstein crossover scenario
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,Expand
Strong-coupling limit in the evolution from BCS superconductivity to Bose-Einstein condensation
We consider the problem of the crossover from BCS superconductivity to Bose-Einstein condensation in three dimensions for a system of fermions with an attractive interaction, for which we adopt theExpand
Superconductivity from a pseudogapped normal state: A mode-coupling approach to precursor superconductivity
It is generally agreed that the pseudogap state of the underdoped cuprates represents some type of pairing above T c which is postulated to derive from neutral spinon pairs, 1 spin density waveExpand
Pair excitations, collective modes, and gauge invariance in the BCS-Bose-Einstein crossover scenario
In this paper we study the BCS Bose-Einstein condensation ~BEC! crossover scenario within the superconducting state, using a T-matrix approach which yields the ground state proposed by Leggett. HereExpand
Pseudogap state in superconductors: Extended Hartree approach to time-dependent Ginzburg-Landau theory
It is well known that conventional pairing fluctuation theory at the Hartree level leads to a normal-state pseudogap in the fermionic spectrum. This pseudogap arises from bosonic degrees of freedomExpand
Pairing Fluctuation Theory of Superconducting Properties in Underdoped to Overdoped Cuprates
Pseudogap phenomena in the cuprates are of interest not only because of the associated unusual normal-state properties, but more importantly because of the constraints which these phenomena impose onExpand
Emergence of a molecular Bose–Einstein condensate from a Fermi gas
This work reports the direct observation of a molecular Bose–Einstein condensate created solely by adjusting the interaction strength in an ultracold Fermi gas of atoms, which represents one extreme of the predicted BCS–BEC continuum. Expand
Numerical studies of the s-wave pseudogap state and related Tc: the “pairing approximation” theory
Abstract We investigate the pseudogap onset temperature T *, the superconducting transition temperature T c and the general nature of the pseudogap phase using a diagrammatic BCS/Bose–EinsteinExpand
Doping a Mott insulator: Physics of high-temperature superconductivity
This article reviews the physics of high-temperature superconductors from the point of view of the doping of a Mott insulator. The basic electronic structure of cuprates is reviewed, emphasizing theExpand
Superfluid transition temperature in a trapped gas of Fermi atoms with a Feshbach resonance
We investigate strong-coupling effects on the superfluid phase transition in a gas of Fermi atoms with a Feshbach resonance. The Feshbach resonance describes a composite quasiboson that can give riseExpand