Collisionless and hydrodynamic excitations of trapped boson-fermion mixtures

Liu, Xia-Ji; Hu, Hui

doi:10.1103/physreva.67.023613

Cited by 49 publications

(28 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The calculated collective mode frequencies are shown to be in quantitative agreement with experiments [25,27,42]. The extension of the scaling theory to a coupled system was developed in the cases of degenerate Bose-Fermi mixtures [35,67].…”

Section: Scaling Theory For a Coupled Systemsupporting

confidence: 65%

“…The scaling anzatz for the time-dependent density profiles for the Bose and Fermi superfluids are chosen as follows [35,67], respectively…”

Section: Scaling Theory For a Coupled Systemmentioning

confidence: 99%

“…Collective excitations that characterize a system's response to small perturbations constitute one of the main sources of information for understanding the physics of many-body systems [19,20]. In the last two decades, collective modes have been extensively investigated to understand the properties of atomic gases in various systems [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], including bosons [39,40], fermions [41,42], and multi-components, such as spin-orbitcoupled bosons [43] and fermions [44], Bose-Bose mixtures [45] and degenerate Bose-Fermi mixtures [46,47].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Collective oscillation modes of a superfluid Bose–Fermi mixture

Wen

Wang

2019

New J. Phys.

View full text Add to dashboard Cite

In this work, we present a theoretical study for the collective oscillation modes, i.e. quadrupole, radial and axial mode, of a mixture of Bose and Fermi superfluids in the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a molecular Bose-Einstein condensate (BEC) in harmonic trapping potentials with cylindrical symmetry of experimental interest. To this end, we start from the coupled superfluid hydrodynamic equations for the dynamics of Bose-Fermi superfluid mixtures and use the scaling theory that has been developed for a coupled system. The collective oscillation modes of Bose-Fermi superfluid mixtures are found to crucially depend on the overlap integrals of the spatial derivations of density profiles of the Bose and Fermi superfluids at equilibrium. We not only present the explicit expressions for the overlap density integrals, as well as the frequencies of the collective modes provided that the effective Bose-Fermi coupling is weak, but also test the valid regimes of the analytical approximations by numerical calculations in realistic experimental conditions. In the presence of a repulsive Bose-Fermi interaction, we find that the frequencies of the three collective modes of the Bose and Fermi superfluids are all upshifted, and the change speeds of the frequency shifts in the BCS-BEC crossover can characterize the different groundstate phases of the Bose-Fermi superfluid mixtures for different trap geometries. superfluid mixtures of 7 Li-6 Li [1, 2], 41 K-6 Li [6], and 174 Yb-6 Li [5], and the Bose-Fermi interaction gives rise to a rich behavior. In the presence of a repulsive Bose-Fermi interaction, the frequencies of the dipole oscillations of the Bose and Fermi superfluids are both downshifted in the weakly confined direction [1,5,6], and the frequency shifts increase monotonically from the BCS side to the BEC side [48,49]. In contrast, the frequency in the tight confinement for the Bose superfluid is upshifted, whereas the frequency for the Fermi superfluid is still downshifted [6]. The frequency shifts show non-monotonic and resonantlike behaviors in both directions around the BCS side [6], which may be originated from the effects of fermionic pairs breaking [50].It is naturally to ask how Bose-Fermi interaction affects the collective modes of Bose and Fermi superfluids in the BCS-BEC crossover, which is of great interest recently. However, a theoretical study for the collective oscillation modes of Bose-Fermi superfluid mixtures in a realistic experimental situation is highly nontrivial. In this work, to study quadrupole, radial and axial modes in cylindrically symmetric traps, we start from the coupled superfluid hydrodynamic equations describing the dynamics of the Bose-Fermi superfluid mixtures. The scaling method for coupled systems is then applied, and the eigenvalue equations for the coupled collective modes are obtained, which are crucially sensitive to the overlap integrals of the spatial derivations of the Bose and Fermi densities at groundstate. To present the explicit expressio...

show abstract

Section: Scaling Theory For a Coupled Systemsupporting

confidence: 65%

“…The scaling anzatz for the time-dependent density profiles for the Bose and Fermi superfluids are chosen as follows [35,67], respectively…”

Section: Scaling Theory For a Coupled Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Collective oscillation modes of a superfluid Bose–Fermi mixture

Wen

Wang

2019

New J. Phys.

View full text Add to dashboard Cite

show abstract

“…For the case of attractive interactions some analyses using semianalytical methods [26,27] have suggested that the lowest-lying monopolar mode should show a softening in the approach to collapse. A similar frequency softening is found for a pure condensate with increasingly large boson attractions [28,29].…”

Section: Introductionmentioning

confidence: 99%

Collisional oscillations of trapped boson-fermion mixtures in the approach to the collapse instability

2004

View full text Add to dashboard Cite

We study the collective modes of a confined gaseous cloud of bosons and fermions with mutual attractive interactions at zero temperature. The cloud consists of a Bose-Einstein condensate and a spin-polarized Fermi gas inside a spherical harmonic trap and the coupling between the two species is varied by increasing either the magnitude of the interspecies s-wave scattering length or the number of bosons. The mode frequencies are obtained in the collisional regime by solving the equations of generalized hydrodynamics and are compared with the spectra calculated in the collisionless regime within a random-phase approximation. We find that, as the mixture is driven towards the collapse instability, the frequencies of the modes of fermionic origin show a blue shift which can become very significant for large numbers of bosons. Instead the modes of bosonic origin show a softening, which becomes most pronounced in the very proximity of collapse. Explicit illustrations of these trends are given for the monopolar spectra, but similar trends are found for the dipolar and quadrupolar spectra except for the surface ͑n =0͒ modes which are essentially unaffected by the interactions.

show abstract

“…A thorough stability consideration was made for the homogeneous case [28] but has not been generalized to trapped systems yet. Finally, the influence of finite temperature [29,30] and beyond mean-field effects [31][32][33][34] have also been investigated.…”

Section: The Richness Of Bose-fermi Mixturesmentioning

confidence: 99%

Comprehensive classification for Bose–Fermi mixtures

et al. 2017

View full text Add to dashboard Cite

We present analytical studies of a trapped boson-fermion mixture at zero temperature with spinpolarized fermions. Using the Thomas-Fermi approximation for bosons and the local-density approximation for fermions, we find a large variety of different density shapes. In the case of continuous density, we obtain analytic conditions for each configuration for attractive as well as repulsive boson-fermion interaction. Furthermore, we analytically show that all the scenarios we describe are minima of the grand-canonical energy functional. Finally, we provide a full classification of all possible ground states in the interpenetrative regime. Our results also apply to binary mixtures of bosons.

show abstract

Collisionless and hydrodynamic excitations of trapped boson-fermion mixtures

Cited by 49 publications

References 48 publications

Collective oscillation modes of a superfluid Bose–Fermi mixture

Collective oscillation modes of a superfluid Bose–Fermi mixture

Collisional oscillations of trapped boson-fermion mixtures in the approach to the collapse instability

Comprehensive classification for Bose–Fermi mixtures

Contact Info

Product

Resources

About