The BCS–BEC Crossover and the Unitary Fermi Gas

Randeria, Mohit; Zwerger, W.; Zwierlein, Martin

doi:10.1007/978-3-642-21978-8_1

Cited by 130 publications

(123 citation statements)

References 199 publications

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“…1 is the Bertsch parameter [35], ζ ≈ ν ≈ 1 are two universal constants [36]. [39,40] (magenta band and purple stars), and effective field theory [33].…”

Section: Constraining the Parameters Of The Single-nucleon Momenmentioning

confidence: 99%

Isospin quartic term in the kinetic energy of neutron-rich nucleonic matter

Cai

2015

Phys. Rev. C

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The energy of a free gas of neutrons and protons is well known to be approximately isospin parabolic with a negligibly small quartic term of only 0.45 MeV at the saturation density of nuclear matter ρ0 = 0.16 fm −3 . Using an isospin-dependent single-nucleon momentum distribution including a high (low) momentum tail (depletion) with its shape parameters constrained by recent high-energy electron scattering and medium-energy nuclear photodisintegration experiments as well as the stateof-the-art calculations of the deuteron wave function and the equation of state of pure neutron matter near the unitary limit within several modern microscopic many-body theories, we show for the first time that the kinetic energy of interacting nucleons in neutron-rich nucleonic matter has a significant quartic term of 7.18 ± 2.52 MeV. Such a large quartic term has broad ramifications in determining the equation of state of neutron-rich nucleonic matter using observables of nuclear reactions and neutron stars.

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“…1 is the Bertsch parameter [35], ζ ≈ ν ≈ 1 are two universal constants [36]. [39,40] (magenta band and purple stars), and effective field theory [33].…”

Section: Constraining the Parameters Of The Single-nucleon Momenmentioning

confidence: 99%

Isospin quartic term in the kinetic energy of neutron-rich nucleonic matter

Cai

2015

Phys. Rev. C

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“…nity to explore the KZ mechanism in a setting where the system's microscopic description can be consistently tuned. In the vicinity of a Feshbach resonance, as the scattering length between the spin-up and spin-down fermions is tuned from positive to negative, the nature of superfluidity changes from Bose-Einstein condensation (BEC) of tightly bound molecules to Bardeen-Cooper-Schrieffer (BCS) superfluidity of long-range fermion pairs (13,14). This leads to significant variations in the static and dynamic properties of the superfluid, as apparent in the changes of the critical temperature (15)(16)(17) and the critical velocity (18)(19)(20) in the BEC-BCS crossover.…”

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confidence: 99%

Kibble–Zurek universality in a strongly interacting Fermi superfluid

Park

Shin

2019

Nat. Phys.

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Near a continuous phase transition, systems with different microscopic origins display universal dynamics if their underlying symmetries are compatible. In a thermally quenched system, the Kibble-Zurek mechanism for the creation of topological defects unveils this universality through a characteristic power-law exponent, which captures the dependence of the defect density on the quench rate. Here, we report the observation of the Kibble-Zurek universality in a strongly interacting Fermi superfluid. As the system's microscopic description is tuned from bosonic to fermionic, the quench formation of vortices reveals a constant scaling exponent arising from the U (1) gauge symmetry of the system.For rapid quenches, destructive vortex collisions lead to the saturation of their densities, whose values can be universally scaled by the interaction-dependent area of the vortex cores.

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“…Prominent examples include reaching the strongly interacting regime of bosonic and fermionic gases in optical lattices [2][3][4][5][6] and studies of the BEC-BCS crossover by means of Feshbach resonances [7][8][9]. The success of this approach is based on the high degree of control that has been achieved over experimental parameters.…”

Section: Introductionmentioning

confidence: 99%

“…This includes, e.g., the study of out-of-equilibrium dynamics of bosonic systems [43] or the equation of state measurement for fermions at the BEC-BCS crossover (see Refs. [1,9] and references therein). Such experimental results can, in turn, be used to check or falsify theoretical treatments, where the quantitative validity of the latter is not a priori guaranteed.…”

Section: Introductionmentioning

confidence: 99%

Probing Correlated Quantum Many-Body Systems at the Single-Particle Level

Endres

2014

Springer Theses

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SummaryThe detection of correlation and response functions plays a crucial role in the experimental characterization of quantum many-body systems. In this thesis, we present novel techniques for the measurement of such functions at the single-particle level. Specifically, we show the single-atom-and single-site-resolved detection of an ultracold quantum gas in an optical lattice. The quantum gas is described by the Bose-Hubbard model, which features a zero temperature phase transition from a superfluid to a Mott-insulating state, a paradigm example of a quantum phase transition. We used the aforementioned detection techniques to study correlation and response properties across the superfluid-Mott-insulator transition.The single-atom sensitivity of our method is achieved by fluorescence detection of individual atoms with a high signal-to-noise ratio. A high-resolution objective collects the fluorescence light and yields in situ 'snapshots' of the quantum gas that allow for a single-site-resolved reconstruction of the atomic distribution. This allowed us to measure two-site and non-local correlation-functions across the superfluid-Mott-insulator transition. Non-local correlation functions are based on the information of an extended region of the system and play an important role for the characterization of low-dimensional quantum phases. While non-local correlation functions were so far only theoretical tools, our results show that they are actually experimentally accessible.Furthermore, we used a new thermometry scheme, based on the counting of individual thermal excitations, to measure the response of the system to lattice modulation. Using this method, we studied the excitation spectrum of the system across the two-dimensional superfluid-Mott-insulator transition. In particular, we detected a 'Higgs' amplitude mode in the strongly-interacting superfluid close to the transition point where the system is described by an effectively Lorentz-invariant low-energy theory. Our experimental results helped to resolve a debate about the observability of Higgs modes in two-dimensional systems.

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The BCS–BEC Crossover and the Unitary Fermi Gas

Cited by 130 publications

References 199 publications

Isospin quartic term in the kinetic energy of neutron-rich nucleonic matter

Isospin quartic term in the kinetic energy of neutron-rich nucleonic matter

Kibble–Zurek universality in a strongly interacting Fermi superfluid

Probing Correlated Quantum Many-Body Systems at the Single-Particle Level

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