Role of interactions in spin-polarized atomic Fermi gases at unitarity

Recati, Alessio; Lobo, Carlos; Stringari, S.

doi:10.1103/physreva.78.023633

Cited by 39 publications

(84 citation statements)

References 41 publications

(56 reference statements)

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“…By comparing ω sf with ω n everywhere in the trap, we can determine which of the two phases is locally most favorable and calculate the particle densities from the corresponding equation of state [199]. For the superfluid phase, the local particle densities are obtained from µ(r) = (1 + β MC ) F (r).…”

Section: Density Profilesmentioning

confidence: 99%

Imbalanced Fermi gases at unitarity

2013

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We consider imbalanced Fermi gases with strong attractive interactions, for which Cooper-pair formation plays an important role. The two-component mixtures consist either of identical fermionic atoms in two different hyperfine states, or of two different atomic species both occupying only a single hyperfine state. In both cases, the number of atoms for each component is allowed to be different, which leads to a spin imbalance, or spin polarization. Two different atomic species also lead to a mass imbalance. Imbalanced Fermi gases are relevant to condensed-matter physics, nuclear physics and astroparticle physics. They have been studied intensively in recent years, following their experimental realization in ultracold atomic Fermi gases. The experimental control in such a system allows for a systematic study of the equation of state and the phase diagram as a function of temperature, spin polarization and interaction strength. In this review, we discuss the progress in understanding strongly-interacting imbalanced Fermi gases, where a main goal is to describe the results of the highly controlled experiments. We start by discussing Feshbach resonances, after which we treat the imbalanced Fermi gas in mean-field theory to give an introduction to the relevant physics. We encounter several unusual superfluid phases, including phase-separation, gapless Sarma superfluidity, and supersolidity. To obtain a more quantitative description of the experiments, we review also more sophisticated techniques, such as diagrammatic methods and the renormalization-group theory. We end the review by discussing two theoretical approaches to treat the inhomogeneous imbalanced Fermi gas, namely the Landau-Ginzburg theory and the Bogoliubov-de Gennes approach.

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Section: Density Profilesmentioning

confidence: 99%

Imbalanced Fermi gases at unitarity

2013

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“…In the following we consider an ansatz for the energy density functional E tot which consists of a part describing an unpolarized (symmetric) superfluid phase in the center of the trap (|r| ≤ R s ) and a part describing a partially-polarized normal Fermi liquid for |r| > R s , see [17]:…”

Section: Fermi Gases In a Harmonic Trapmentioning

confidence: 99%

“…This scattering length can be considered a free parameter which can be tuned by hand by means of an external magnetic field [1]. Phases of ultracold Fermi gases at zero and finite temperature have been studied experimentally, see e.g., [2,3] as well as theoretically, see e.g., [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], over the past few years. In particular, studies of ultracold gases with renormalization group (RG) methods [14,16] exhibit many technical similarities to studies of QCD at finite temperature and density, see e.g., [21,22].…”

Section: Introductionmentioning

confidence: 99%

Phase Structure of Strongly Interacting Theories and Finite-Size Effects

Braun

2011

Few-Body Syst

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Strongly interacting theories of fermions are of great interest both experimentally and theoretically. While heavy-ion collision experiments provide us with information on hot and dense QCD, experiments with ultracold trapped atoms provide an accessible and controllable system where quantum many-body phenomena can be studied experimentally in great detail. Our theoretical understanding of these theories has improved in recent years. However, finite-size effects in these systems are not yet fully understood. We review some aspects related to finite-size effects and the role that these effects are playing in strongly-interacting fermionic theories.

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“…This effect is a clear manifestation of the phase separation. Note that Monte Carlo simulations suggest that the LDA boundary of the superfluid phase is slightly overestimated [55,56].…”

Section: External Harmonic Confinement and Local-density Approximationmentioning

confidence: 99%

Pair condensation of polarized fermions in the BCS–BEC crossover

Bighin¹,

Mazzarella²,

Dell’Anna³

et al. 2014

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. We investigate a two-component Fermi gas with unequal spin populations along the BCS-BEC crossover. By using the extended BCS equations and the concept of off-diagonal-long-range-order we derive a formula for the condensate number of Cooper pairs as a function of energy gap, average chemical potential, imbalance chemical potential and temperature. Then we study the zero-temperature condensate fraction of Cooper pairs by varying interaction strength and polarization, finding a depletion of the condensate fraction by increasing the population imbalance. We also consider explicitly the presence of an external harmonic confinement and we study, within the local-density approximation, the phase separation between superfluid and normal phase regions of the polarized fermionic cloud. In particular, we calculate both condensate density profiles and total density profiles from the inner superfluid core to the normal region passing for the interface, where a finite jump in the density is a clear manifestation of this phase-separated regime. Finally, we compare our theoretical results with the available experimental data on the condensate fraction of polarized 6 Li atoms [Science 311, 492 (2006)]. These experimental data are in reasonable agreement with our predictions in a suitable range of polarizations, but only in the BCS side of the crossover up to unitarity.PACS numbers: 03.75. Ss, 05.30.Fk, 67.85.Lm Pair condensation of polarized fermions in the BCS-BEC crossover 2

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Role of interactions in spin-polarized atomic Fermi gases at unitarity

Cited by 39 publications

References 41 publications

Imbalanced Fermi gases at unitarity

Imbalanced Fermi gases at unitarity

Phase Structure of Strongly Interacting Theories and Finite-Size Effects

Pair condensation of polarized fermions in the BCS–BEC crossover

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