Momentum-resolved spectroscopy of a Fermi liquid

Doggen, Elmer V. H.; Kinnunen, Jami J.

doi:10.1038/srep09539

Cited by 11 publications

(27 citation statements)

References 61 publications

(121 reference statements)

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“…Therefore, to be consistent, one should a priori compare with the value of the Bertsch parameter in normal systems. In [18], using Brueckner Hartree-Fock approach, a value 0.507 was found, which is compatible with the experimental result of Ref. [94] giving 0.45.…”

Section: Diagrammatic Resummation Technique For the Energysupporting

confidence: 88%

“…Although the main goal of the present work is to obtain DFT suitable beyond the perturbative regime, we would like to mention also that the approximated form (18) leads to a Bertsch parameter ξ GPS = 0.32, that is closer to the one obtain at unitarity for superfluid systems [24,39] compared to the one obtained with direct integration. It should be noted however that a relatively small difference in the value of ξ 0 leads to large deviations in the energy due to the fact that it is multiplied by the Free-Gas energy.…”

Section: Phase-space Average Approximation For the Re-summed Energymentioning

confidence: 70%

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Approximate self-energy for Fermi systems with large s-wave scattering length: a step towards density functional theory

Boulet¹,

Lacroix²

2019

J. Phys. G: Nucl. Part. Phys.

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In the present work, we start from a minimal Hamiltonian for Fermi systems where the s-wave scattering is the only low energy constant at play. Many-Body Perturbative approach that is usually valid at rather low density is first discussed. We then use the resummation technique with the ladder approximation to obtain compact expressions for both the energy and/or the on-shell self-energy in infinite spin-degenerated systems. Diagrammatic resummation technique has the advantage in general to be predictive in a region of density larger compared to many-body perturbation theory. It also leads to non-diverging limit as |a s | → +∞. Still, the obtained expressions are rather complex functional of the Fermi momentum k F . We introduce the full phase-space average or the partial phase-space methods respectively applied to the energy or to the self-energy to simplify their dependences in terms of (a s k F ) while keeping the correct limit at low density and the non-diverging property at large |a s k F |. Quasi-particle properties of Fermi system in various regime of density and scattering length are then illustrated. Our conclusion is that such simplified expressions where the direct link is made with the low energy constant without finetuning can provide a clear guidance to obtain density functional theory beyond the perturbative regime. However, quasi-particle properties close or near unitary cannot be reproduced unless this limit is explicitly used as a constraint. We finally discuss how such approximate treatment of quasi-particle can guide the development of density functional theory for strongly interacting Fermi systems. arXiv:1902.05477v1 [nucl-th]

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Section: Diagrammatic Resummation Technique For the Energysupporting

confidence: 88%

Section: Phase-space Average Approximation For the Re-summed Energymentioning

confidence: 70%

Approximate self-energy for Fermi systems with large s-wave scattering length: a step towards density functional theory

Boulet¹,

Lacroix²

2019

J. Phys. G: Nucl. Part. Phys.

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“…Superfluidity has been reported in such systems [13][14][15][16], also in the case where the fermions are confined to an optical lattice [17]. Moreover, based on rf spectroscopy, PG signatures have been reported for two- [18] and three-dimensional systems without optical lattices [19][20][21].…”

Section: Introductionmentioning

confidence: 96%

Local origin of the pseudogap in the attractive Hubbard model

Peters

Bauer

2015

Phys. Rev. B

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We provide a new perspective on the pseudogap physics for attractive fermions as described by the three-dimensional Hubbard model. The pseudogap in the single-particle spectral function, which occurs for temperatures above the critical temperature $T_c$ of the superfluid transition, is often interpreted in terms of preformed, uncondensed pairs. Here we show that the occurrence of pseudogap physics can be consistently understood in terms of local excitations which lead to a splitting of the quasiparticle peak for sufficiently large interaction. This effect becomes prominent at intermediate and high temperatures when the quantum mechanical hopping is incoherent. We clarify the existence of a conjectured temperature below which pseudogap physics is expected to occur. Our results are based on approximating the physics of the three-dimensional Hubbard model by dynamical mean field theory calculations and a momentum independent self-energy. Our predictions can be tested with ultracold atoms in optical lattices with currently available temperatures and spectroscopic techniques.Comment: 15 pages including appendix; suggestions for further references welcom

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“…where have implemented momentum conservation by requiring that p = q +r −k. In order to evaluate the above integrals numerically in the large k limit, it is convenient to parametrize [36] q = (p + k)/2 + s, r = (p + k)/2 − s. The result of the numerical evaluation of δn k (T r , t) is shown in Figure 5 as a function of k/k F for t = 20E −1 F . For this time, δn k (T r , t) has reached a stationary value.…”

Section: Change Of Momentum Distribution After a Ramp Quenchmentioning

confidence: 99%

“…where C eq is the equilibrium contact calculated to leading order in perturbation theory (see Ref. [36] and below). The above relation is similar to the relation obeyed in the pre-thermalized regime by the discontinuity of the momentum distribution at the Fermi momentum, Eq.…”

Section: Change Of Momentum Distribution After a Ramp Quenchmentioning

confidence: 99%

Total energy dynamics and asymptotics of the momentum distribution following an interaction quench in a two-component Fermi gas

Huang

Cazalilla

2019

Phys. Rev. A

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The absence of a characteristic momentum scale in the pseudo-potential description of atomic interactions in ultracold (two-component Fermi) gases is known to lead to divergences in perturbation theory. Here we show that they also plague the calculation of the dynamics of the total energy following a quantum quench. A procedure to remove the divergences is devised, which provides finite answers for the time-evolution of the total energy after a quench in which the interaction strength is ramped up according to an arbitrary protocol. An important result of this analysis is the time evolution of the asymptotic tail of the momentum distribution (related to Tan's contact) to leading order in the scattering length. Explicit expressions for the dynamics of the total energy and the contact for a linear interaction ramp are obtained, as a function of the interaction ramp time in the crossover from the sudden quench to the adiabatic limit are reported. In sudden quench limit, the contact, following a rapid oscillation, reaches a stationary value which is different from the equilibrium one. In the adiabatic limit, the contact grows quadratically in time and later saturates to its equilibrium value for the final value of the scattering length.

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Momentum-resolved spectroscopy of a Fermi liquid

Cited by 11 publications

References 61 publications

Approximate self-energy for Fermi systems with large s-wave scattering length: a step towards density functional theory

Approximate self-energy for Fermi systems with large s-wave scattering length: a step towards density functional theory

Local origin of the pseudogap in the attractive Hubbard model

Total energy dynamics and asymptotics of the momentum distribution following an interaction quench in a two-component Fermi gas

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