Density-induced BCS to Bose-Einstein crossover

Andrenacci, Natascia; Perali, Andrea; Pieri, P.; Strinati, G. C.

doi:10.1103/physrevb.60.12410

Cited by 78 publications

(123 citation statements)

References 23 publications

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“…8). This situation is analogous to the d-wave lattice case 50,51 . As the interaction is further increased, similar behavior oc-curs in case (II).…”

Section: E Average Cooper Pair Sizementioning

confidence: 99%

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Iskin¹,

Melo²

2005

Phys. Rev. B

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We consider p-wave pairing of single hyperfine state and s-wave pairing of two hyperfine states ultracold atomic gases trapped in quasi-two-dimensional optical lattices. First, we analyse superfluid properties of p-wave and s-wave symmetries in the strictly weak coupling BCS regime where we discuss the order parameter, chemical potential, critical temperature, atomic compressibility and superfluid density as a function of filling factor for tetragonal and orthorhombic optical lattices. Second, we analyse superfluid properties of p-wave and s-wave superfluids in the evolution from BCS to BEC regime at low temperatures (T ≈ 0), where we discuss the changes in the quasi-particle excitation spectrum, chemical potential, atomic compressibility, Cooper pair size and momentum distribution as a function of filling factor and interaction strength for tetragonal and orthorhombic optical lattices.

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“…8). This situation is analogous to the d-wave lattice case 50,51 . As the interaction is further increased, similar behavior oc-curs in case (II).…”

Section: E Average Cooper Pair Sizementioning

confidence: 99%

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Iskin¹,

Melo²

2005

Phys. Rev. B

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“…The BCS to BEC evolution of d-wave (ℓ = 2) superfluidity was discussed previously in the literature using continuum 27,28,29 and lattice 30,31 descriptions in connection to high-T c superconductivity. More recently, p-wave superfluidity was analyzed at T = 0 for two hyperfine state (THS) systems in 3D 32 , and for single hyperfine state (SHS) systems in two dimensions (2D) 33,34,35 , using fermion-only models.…”

Section: Introductionmentioning

confidence: 99%

Nonzero orbital angular momentum superfluidity in ultracold Fermi gases

Iskin¹,

Melo

2006

Phys. Rev. A

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We analyze the evolution of superfluidity for nonzero orbital angular momentum channels from the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein condensation (BEC) limit in three dimensions. First, we analyze the low energy scattering properties of finite range interactions for all possible angular momentum channels. Second, we discuss ground state (T = 0) superfluid properties including the order parameter, chemical potential, quasiparticle excitation spectrum, momentum distribution, atomic compressibility, ground state energy and low energy collective excitations. We show that a quantum phase transition occurs for nonzero angular momentum pairing, unlike the s-wave case where the BCS to BEC evolution is just a crossover. Third, we present a gaussian fluctuation theory near the critical temperature (T = Tc), and we analyze the number of bound, scattering and unbound fermions as well as the chemical potential. Finally, we derive the time-dependent Ginzburg-Landau functional near Tc, and compare the Ginzburg-Landau coherence length with the zero temperature average Cooper pair size.

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“…Expanding ǫ x in powers of ζ, ǫ x = x 2 + 2ζ −2 + O(ζ 2 ), we can recover the nonrelativistic version of ξ x . However, we can not simply neglect the terms corresponding to anti-fermions, namely the second terms on the right hand side of Equations (14). Such terms can be neglected only when |µ − m| and ∆ 0 are both much less than m. When the coupling is so strong to ensure µ → 0, the contribution from anti-fermions becomes significant.…”

Section: Relativistic Effects In Bcs-bec Crossovermentioning

confidence: 99%

“…However, if the universality is broken, there would exist an extra density dependence which may induce a BCS-BEC crossover. In non-relativistic Fermi gas, the breaking of the universality can be induced by a finite range interaction [14]. In the relativistic theory, the universality is naturally broken by the ζ = k f /m dependence which leads to the extra density effect.…”

Section: Density Effect In Bcs-bec Crossovermentioning

confidence: 99%

Relativistic BCS-BEC crossover at zero temperature

Zhuang

2007

Phys. Rev. D

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We investigate the BCS-BEC crossover at zero temperature in the frame of a relativistic model. The universality of the BCS-BEC crossover for non-relativistic systems breaks down in relativistic case and the crossover can be induced by changing the density. When the effective scattering length is much less than the fermion Compton wavelength, we recover the non-relativistic result if the gas is initially in non-relativistic state. At ultra-strong coupling where the scattering length is of the order of the Compton wavelength, a new BEC state appears. In this state the condensed bosons become nearly massless and anti-fermions are excited. The behavior of the Goldstone mode and the mixing between the amplitude and phase modes are significantly different in different condensed regions.

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Density-induced BCS to Bose-Einstein crossover

Cited by 78 publications

References 23 publications

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Superfluidity ofp-wave ands-wave atomic Fermi gases in optical lattices

Nonzero orbital angular momentum superfluidity in ultracold Fermi gases

Relativistic BCS-BEC crossover at zero temperature

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