Schematic phase diagram and collective excitations in the collisional regime for trapped boson–fermion mixtures at zero temperature

Minguzzi, Anna; Tosi, M. P.

doi:10.1016/s0375-9601(00)00154-7

Cited by 31 publications

(34 citation statements)

References 32 publications

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“…For high number of bosons, this is well reproduced by Stringari's hydrodynamic formulation [28], which provides an analytic expression for the multipolar excitation energies. Although analytic formulae have been also found for systems of interacting fermions [15,21], they hold in the hydrodynamic regime and for population ranges far from those we address here, so we compare our results with earlier numerical calculations carried within the collisionless regime.…”

Section: B Random-phase Approximationmentioning

confidence: 69%

Zero-sound density oscillations in Fermi-Bose mixtures

Capuzzi

Hernández

2001

Phys. Rev. A

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Within a mean field plus Random-Phase Approximation formalism, we investigate the collective excitations of a three component Fermi-Bose mixture of K atoms, magnetically trapped and subjected to repulsive s-wave interactions. We analyze both the single-particle excitation and the density oscillation spectra created by external multipolar fields, for varying fermion concentrations. The formalism and the numerical output are consistent with the Generalized Kohn Theorem for the whole multispecies system. The calculations give rise to fragmented density excitation spectra of the fermion sample and illustrate the role of the mutual interaction in the observed deviations of the bosonic spectra with respect to Stringari's rule.

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Section: B Random-phase Approximationmentioning

confidence: 69%

Zero-sound density oscillations in Fermi-Bose mixtures

Capuzzi

Hernández

2001

Phys. Rev. A

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“…The latter system is in particular interesting since it serves as one typical example in which the intermingled particles obey different statistics. Up to date the static property [10,11,12,13], the phase diagram and phase separation [14,15,16], stability conditions [17,18] and collective excitations [19,20,21,22,23,24,25,26] of trapped boson-fermion mixtures have been theoretically investigated. In a recent experiment, the collapse of a degenerated Fermi gas caused by the strong attractive interaction with a Bose-Einstein condensate has been observed in an atomic mixture of 40 K− 87 Rb [27], and measurements of collective excitations might be available soon also in such systems.…”

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confidence: 99%

“…The collisionless modes are considered by a sumrule approach [24] or in the random-phase approximation [25,26]. The collisional collective oscillations are discussed by Minguzzi and Tosi [23], however, limited to the surface modes at weak fermion-boson coupling. On the other hand, the homogeneous boson-fermion mixtures have also been analytically studied [19,20,21,22].…”

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confidence: 99%

Collisionless and hydrodynamic excitations of trapped boson-fermion mixtures

Liu

2003

Phys. Rev. A

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Within a scaling ansatz formalism plus Thomas-Fermi approximation, we investigate the collective excitations of a harmonically trapped boson-fermion mixture in the collisionless and hydrodynamic limit at low temperature. Both the monopole and quadrupole modes are considered in the presence of spherical as well as cylindrically symmetric traps. In the spherical traps, the frequency of monopole mode coincides in the collisionless and hydrodynamic regime, suggesting that it might be undamped in all collisional regimes. In contrast, for the quadrupole mode, the frequency differs largely in these two limits. In particular, we find that in the hydrodynamic regime the quadrupole oscillations with equal bosonic and fermionic amplitudes generate an exact eigenstate of the system, regardless of the boson-fermion interaction. This resembles the Kohn mode for the dipole excitation. We discuss in some detail the behavior of monopole and quadrupole modes as a function of boson-1 fermion coupling at different boson-boson interaction strength. Analytic solutions valid at weak and medium fermion-boson coupling are also derived and discussed.

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“…Motivated by the controllability of various experimental parameters such as trap geometries, particle numbers, and interaction strengths in experiments of ultracold atoms, a number of theoretical studies have been done to explain various experimental results done for Bose-Fermi mixtures [6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Peierls instability, periodic Bose-Einstein condensates, and density waves in quasi-one-dimensional boson-fermion mixtures of atomic gases

2004

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We study the quasi-one-dimensional (Q1D) spin-polarized Bose-Fermi mixture of atomic gases at zero temperature. Bosonic excitation spectra are calculated in the random phase approximation on the ground state with uniform Bose-Einstein condensates (BEC's) and the Peierls instabilities are shown to appear in bosonic collective excitation modes with wave number 2k F by the coupling between the Bogoliubov-phonon mode of bosonic atoms and the fermion particle-hole excitations. The ground-state properties are calculated in the variational method, and, corresponding to the Peierls instability, the state with a periodic BEC and fermionic density waves with the period / k F are shown to have a lower energy than the uniform one. We also briefly discuss the Q1D system confined in a harmonic oscillator potential and derive the Peierls instability condition for it. We consider a system of spin-polarized atoms at T =0: N b bosons and N f fermions with masses m b,f each other, confined in an axially symmetric HO potential U b,f = 1 2 m b,f ͕ r 2 ͑x 2 + y 2 ͒ + a 2 z 2 ͖ where r ӷ a . When atoms are confined tightly enough in the r direction that the radial ͑r͒ *

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Schematic phase diagram and collective excitations in the collisional regime for trapped boson–fermion mixtures at zero temperature

Cited by 31 publications

References 32 publications

Zero-sound density oscillations in Fermi-Bose mixtures

Zero-sound density oscillations in Fermi-Bose mixtures

Collisionless and hydrodynamic excitations of trapped boson-fermion mixtures

Peierls instability, periodic Bose-Einstein condensates, and density waves in quasi-one-dimensional boson-fermion mixtures of atomic gases

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