Physical dipoles and second-order perturbation theory for dipolar fermions in two dimensions

Lange, Philipp; Krieg, J.; Kopietz, Peter

doi:10.1103/physreva.93.033609

Cited by 10 publications

(9 citation statements)

References 45 publications

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“…In the current experimentally relevant range of dipolar interactions the theory beyond Hartree-Fock, where the total energy is determined up to second-order in the DDI, yields only small differences, which cannot yet be resolved experimentally. Thus, the Hartree-Fock mean-field approximation yields already quantitatively accurate results for present-day experiments [48][49][50].…”

Section: Introductionmentioning

confidence: 71%

Time-of-flight expansion of trapped dipolar Fermi gases: From the collisionless to the hydrodynamic regime

2017

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A recent time-of-flight (TOF) expansion experiment with polarized fermionic erbium atoms measured a Fermi surface deformation from a sphere to an ellipsoid due to dipole-dipole interaction, thus confirming previous theoretical predictions. Here we perform a systematic study of the ground-state properties and TOF dynamics for trapped dipolar Fermi gases from the collisionless to the hydrodynamic regime at zero temperature. To this end we solve analytically the underlying BoltzmannVlasov equation within the relaxation-time approximation in the vicinity of equilibrium by using a suitable rescaling of the equilibrium distribution. The resulting ordinary differential equations for the respective scaling parameters are then solved numerically for experimentally realistic parameters and relaxation times that correspond to the collisionless, collisional, and hydrodynamic regime. The equations for the collisional regime are first solved in the approximation of a fixed relaxation time, and then this approach is extended to include a self-consistent determination of the relaxation time. The presented analytical and numerical results are relevant for a detailed quantitative understanding of ongoing experiments and the design of future experiments with ultracold fermionic dipolar atoms and molecules. In particular, the obtained results are relevant for systems with strong dipole-dipole interaction, which turn out to affect significantly the aspect ratios during the TOF expansion.

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Section: Introductionmentioning

confidence: 71%

Time-of-flight expansion of trapped dipolar Fermi gases: From the collisionless to the hydrodynamic regime

2017

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“…The Fourier transform of 1/r 3 in two dimensions is not well-defined, unless a regularization scheme is used -see for instance Ref. [64]. In the derivation of Eq.…”

Section: A Equation Of State: Analytical Approximationsmentioning

confidence: 99%

Two-dimensional mixture of dipolar fermions: Equation of state and magnetic phases

et al. 2019

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We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive 1/r 3 potential. This model can be realized with ultracold atoms or molecules, when their dipole moments are aligned in the confinement direction orthogonal to the plane. We characterize the unpolarized mixture by means of the Diffusion Monte Carlo technique. Computing the equation of state, we identify the regime of validity for a mean-field theory based on a low-density expansion and compare our results with the hard-disk model of repulsive fermions. At high density, we address the possibility of itinerant ferromagnetism, namely whether the ground state can be fully polarized in the fluid phase. Within the fixed-node approximation, we show that the accuracy of Jastrow-Slater trial wave functions, even with the typical two-body backflow correction, is not sufficient to resolve the relevant energy differences. By making use of the iterativebackflow improved trial wave functions, we observe no signature of a fully-polarized ground state up to the freezing density. arXiv:1812.08064v2 [cond-mat.quant-gas]

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“…where C dd is the dipole-dipole coupling constant, r is the in-plane distance between two dipoles. After Fourier transformation one finds [33,58]…”

Section: Density-density Response Function and The Effective Interactmentioning

confidence: 99%

Density-wave instability and collective modes in a bilayer system of antiparallel dipoles

2018

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We consider a bilayer of dipolar particles in which the polarization of dipoles is perpendicular to the planes, in the antiparallel configuration. Using accurate static structure factor ( ) S q data from hypernetted-chain (HNC) and Fermi HNC calculations, respectively for an isolated layer of dipolar bosons and dipolar fermions, we construct effective screened intralayer interactions. Adopting the random-phase approximation for interlayer interactions, we investigate the instability of these homogeneous bilayer systems towards the formation of density waves by studying the poles of the density-density response function. We have also studied the collective modes of these systems and find that the dispersion of their antisymmetric collective mode signals the emergence of the density wave instability as well.

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Physical dipoles and second-order perturbation theory for dipolar fermions in two dimensions

Cited by 10 publications

References 45 publications

Time-of-flight expansion of trapped dipolar Fermi gases: From the collisionless to the hydrodynamic regime

Time-of-flight expansion of trapped dipolar Fermi gases: From the collisionless to the hydrodynamic regime

Two-dimensional mixture of dipolar fermions: Equation of state and magnetic phases

Density-wave instability and collective modes in a bilayer system of antiparallel dipoles

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