The BCS-BEC Crossover and the Unitary Fermi Gas

Bulgac, Aurel; Forbes, Michael McNeil; Magierski, Piotr

doi:10.1007/978-3-642-21978-8

Cited by 231 publications

(84 citation statements)

References 145 publications

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“…Over the past years, ultracold atoms in optical lattices have become a fascinating tool to explore strongly correlated many-body systems and thereby provide also valuable insights into complex phenomena in solid-state systems [1][2][3]. Ultracold-atom-based quantum simulators have already been used, e.g., to observe the transition from a superfluid (SF) to a Mott insulator (MI) phase for bosons [4], to realize the crossover between Bose-Einstein condensation and Bardeen-Cooper-Schrieffer pairing [5], or to modulate the range of interactions in quantum systems [6,7].…”

Section: Introductionmentioning

confidence: 99%

Quantum phase transitions in the dimerized extended Bose-Hubbard model

2019

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We present an unbiased numerical density-matrix renormalization group study of the onedimensional Bose-Hubbard model supplemented by nearest-neighbor Coulomb interaction and bond dimerization. It places the emphasis on the determination of the ground-state phase diagram and shows that, besides dimerized Mott and density-wave insulating phases, an intermediate symmetryprotected topological Haldane insulator emerges at weak Coulomb interactions for filling factor one, which disappears, however, when the dimerization becomes too large. Analyzing the critical behavior of the model, we prove that the phase boundaries of the Haldane phase to Mott insulator and density-wave states belong to the Gaussian and Ising universality classes with central charges c = 1 and c = 1/2, respectively, and merge in a tricritical point. Interestingly we can demonstrate a direct Ising quantum phase transition between the dimerized Mott and density-wave phases above the tricritical point. The corresponding transition line terminates at a critical end point that belongs to the universality class of the dilute Ising model with c = 7/10. At even stronger Coulomb interactions the transition becomes first order.

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Section: Introductionmentioning

confidence: 99%

Quantum phase transitions in the dimerized extended Bose-Hubbard model

2019

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“…1 we present a schematic phase diagram of adjoint QCD with the aim to illustrate how our analysis in this paper in the small-S 1 regime should fit in the global phase diagram from small to large S 1 . Adjoint QCD on R 4 is believed to exhibit a relativistic analogue of the BEC-BCS crossover [31,32] when the chemical potential is swept across Λ QCD [33][34][35][36][37][38][39][40][41]:…”

Section: Introductionmentioning

confidence: 99%

Phases of circle-compactified QCD with adjoint fermions at finite density

Kanazawa¹,

Ünsal

Yamamoto

2017

Phys. Rev. D

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We study chemical-potential dependence of confinement and mass gap in QCD with adjoint fermions in spacetime with one spatial compact direction. By calculating the one-loop effective potential for the Wilson line in the presence of chemical potential, we show that a center-symmetric phase and a center-broken phase alternate when the chemical potential in unit of the compactification scale is increased. In the center-symmetric phase we use semiclassical methods to show that photons in the magnetic bion plasma acquire a mass gap that grows with the chemical potential as a result of anisotropic interactions between monopole-instantons. For the neutral fermionic sector which remains gapless perturbatively, there are two possibilities at non-perturbative level. Either to remain gapless (unbroken global symmetry), or to undergo a novel superfluid transition through a fourfermion interaction (broken global symmetry). If the latter is the case, this leads to an energy gap of quarks proportional to a new nonperturbative scale L −1 exp[−1 (g 4 µL)], where L denotes the circumference of S 1 , the low-energy is described as a Nambu-Goldstone mode associated with the baryon number, and there exists a new type of BEC-BCS crossover of the diquark pairing as a function of the compactification scale at small chemical potential.

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“…The two-body contact plays an important role in many of the most important probes of ultracold fermionic atoms [11]. Universal relations for identical bosons were first derived by Braaten, Kang, and Platter [15].…”

Section: =3mentioning

confidence: 99%

Two-Body and Three-Body Contacts for Identical Bosons near Unitarity

et al. 2014

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In a recent experiment with ultracold trapped 85 Rb atoms, Makotyn et al. studied a quantum-degenerate Bose gas in the unitary limit where its scattering length is infinitely large. We show that the observed momentum distributions are compatible with a universal relation that expresses the high-momentum tail in terms of the two-body contact C 2 and the three-body contact C 3 . We determine the contact densities for the unitary Bose gas with number density n to be C 2 ≈ 20n 4=3 and C 3 ≈ 2n 5=3 . We also show that the observed atom loss rate is compatible with that from 3-atom inelastic collisions, which gives a contribution proportional to C 3 , but the loss rate is not compatible with that from 2-atom inelastic collisions, which gives a contribution proportional to C 2 . We point out that the contacts C 2 and C 3 could be measured independently by using the virial theorem near and at unitarity, respectively.

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The BCS-BEC Crossover and the Unitary Fermi Gas

Cited by 231 publications

References 145 publications

Quantum phase transitions in the dimerized extended Bose-Hubbard model

Quantum phase transitions in the dimerized extended Bose-Hubbard model

Phases of circle-compactified QCD with adjoint fermions at finite density

Two-Body and Three-Body Contacts for Identical Bosons near Unitarity

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