Hartree shift in unitary Fermi gases

Kinnunen, Jami J.

doi:10.1103/physreva.85.012701

Cited by 22 publications

(30 citation statements)

References 55 publications

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“…The plot reveals the strong momentum dependence of the self-energy, particularly close to unitarity k F a = ±∞. The momentum dependence is easily understood32 when considering the two-body on-shell scattering amplitude, which for the contact interaction pseudopotential isFor large relative momenta , the scattering amplitude is suppressed. Hence, high momentum atoms will interact very weakly with atoms in the Fermi sea and the self-energy is suppressed.…”

Section: Resultsmentioning

confidence: 90%

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Momentum-resolved spectroscopy of a Fermi liquid

Doggen

Kinnunen

2015

Sci Rep

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We consider a recent momentum-resolved radio-frequency spectroscopy experiment, in which Fermi liquid properties of a strongly interacting atomic Fermi gas were studied. Here we show that by extending the Brueckner-Goldstone model, we can formulate a theory that goes beyond basic mean-field theories and that can be used for studying spectroscopies of dilute atomic gases in the strongly interacting regime. The model hosts well-defined quasiparticles and works across a wide range of temperatures and interaction strengths. The theory provides excellent qualitative agreement with the experiment. Comparing the predictions of the present theory with the mean-field Bardeen-Cooper-Schrieffer theory yields insights into the role of pair correlations, Tan's contact, and the Hartree mean-field energy shift.

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Section: Resultsmentioning

confidence: 90%

“…In particular, the imaginary part of the self-energy no longer changes sign at the Fermi surface32. To avoid the problem, we neglect the imaginary part obtained from the Brueckner-Goldstone self-energy altogether and instead use a fixed imaginary part.…”

Section: Methodsmentioning

confidence: 99%

Momentum-resolved spectroscopy of a Fermi liquid

Doggen

Kinnunen

2015

Sci Rep

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“…In this paper, we numerically calculate χ n within the framework of an extended T -matrix approximation (ETMA) [21][22][23][24][25] which has been developed to evaluate the spin susceptibility χ s in the BCS-BEC crossover region. An advantage of ETMA is that one may quantitatively describe the self-energy shift, which is also referred as "Hartree shift" in the previous work [26][27][28]. We compare our results with the recent experiment on a 6 Li Fermi gas, to clarify effects of quantum fluctuations in the whole BCS-BEC crossover region at T = 0.…”

Section: Introductionmentioning

confidence: 71%

Zero-Temperature Properties of a Strongly Interacting Superfluid Fermi Gas in the BCS–BEC Crossover Region

et al. 2016

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We investigate thermodynamic properties and effects of quantum fluctuations in the Bardeen-Cooper-Schrieffer (BCS)-Bose-Einstein condensation (BEC) crossover region of a superfluid Fermi gas in the low-temperature limit. Including strong-coupling corrections within the framework of an extended T -matrix approximation, we numerically compute the isothermal compressibility χ n . While quantum fluctuation effects on χ n in the strong-coupling BEC regime are explained by the quantum depletion due to a repulsive interaction between tightly bound molecules, effects of self-energy shift on the Fermi chemical potential are found to enhance χ n in the weak-coupling BCS region. We also show that the calculated χ n agrees well with the recent experiment on a 6 Li Fermi gas done from the weak-coupling region to the unitarity limit. Our result would be useful for the study of many-body quantum corrections in the BCS-BEC crossover region of a strongly interacting Fermi superfluid.

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“…The Hartree energy [the term proportional to densities n ↑(↓) (r)] is known to be ill behaved in the strongly interacting regime [27,28], causing large perturbations in the density profiles by compressing the gas. In BdG theory the problem manifests already well before the actual divergence of the scattering length: the kinetic-energy cost of adding one more atom to the center of the trap would be…”

Section: Methodsmentioning

confidence: 99%

Collective excitations of a trapped Fermi gas at finite temperature

2014

Self Cite

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We study collective excitations of a trapped Fermi gas at finite temperature using the Bogoliubov-de Gennes mean-field theory in conjunction with the generalized random-phase approximation. The collective excitations are analyzed through the density response of a monopole excitation. We show the appearance of several modes at the normal-fluid-superfluid phase-transition temperature: Higgs mode-like pairing amplitude modulations, analogues of the second sound in the trapped gas, and an edge mode that is also the strongest mode in the response.

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Hartree shift in unitary Fermi gases

Cited by 22 publications

References 55 publications

Momentum-resolved spectroscopy of a Fermi liquid

Momentum-resolved spectroscopy of a Fermi liquid

Zero-Temperature Properties of a Strongly Interacting Superfluid Fermi Gas in the BCS–BEC Crossover Region

Collective excitations of a trapped Fermi gas at finite temperature

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