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Title: Mixing-demixing transition and collapse of a vortex state in a quasi-two-dimensional boson-fermion mixture

Abstract

We investigate the mixing-demixing transition and the collapse in a quasi-two-dimensional degenerate boson-fermion mixture (DBFM) with a bosonic vortex. We solve numerically a quantum-hydrodynamic model based on a new density functional which accurately takes into account the dimensional crossover. It is demonstrated that with the increase of interspecies repulsion, a mixed state of DBFM could turn into a demixed state. The system collapses for interspecies attraction above a critical value which depends on the vortex quantum number. For interspecies attraction just below this critical limit there is almost complete mixing of boson and fermion components. Such mixed and demixed states of a DBFM could be experimentally realized by varying an external magnetic field near a boson-fermion Feshbach resonance, which will result in a continuous variation of interspecies interaction.

Authors:
 [1];  [2]
  1. Instituto de Fisica Teorica, UNESP-Sao Paulo State University, 01.405-900 Sao Paulo, Sao Paulo (Brazil)
  2. CNISM and CNR-INFM, Unita di Padova, Dipartimento di Fisica 'Galileo Galilei', Universita di Padova, Via Marzolo 8, 35131 Padova (Italy)
Publication Date:
OSTI Identifier:
20982563
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.75.053603; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; BOSONS; DENSITY FUNCTIONAL METHOD; FERMIONS; HYDRODYNAMIC MODEL; INTERACTIONS; MAGNETIC FIELDS; MATHEMATICAL MODELS; MIXED STATE; NUMERICAL SOLUTION; RESONANCE; TWO-DIMENSIONAL CALCULATIONS; VORTICES

Citation Formats

Adhikari, Sadhan K., and Salasnich, Luca. Mixing-demixing transition and collapse of a vortex state in a quasi-two-dimensional boson-fermion mixture. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.053603.
Adhikari, Sadhan K., & Salasnich, Luca. Mixing-demixing transition and collapse of a vortex state in a quasi-two-dimensional boson-fermion mixture. United States. doi:10.1103/PHYSREVA.75.053603.
Adhikari, Sadhan K., and Salasnich, Luca. Tue . "Mixing-demixing transition and collapse of a vortex state in a quasi-two-dimensional boson-fermion mixture". United States. doi:10.1103/PHYSREVA.75.053603.
@article{osti_20982563,
title = {Mixing-demixing transition and collapse of a vortex state in a quasi-two-dimensional boson-fermion mixture},
author = {Adhikari, Sadhan K. and Salasnich, Luca},
abstractNote = {We investigate the mixing-demixing transition and the collapse in a quasi-two-dimensional degenerate boson-fermion mixture (DBFM) with a bosonic vortex. We solve numerically a quantum-hydrodynamic model based on a new density functional which accurately takes into account the dimensional crossover. It is demonstrated that with the increase of interspecies repulsion, a mixed state of DBFM could turn into a demixed state. The system collapses for interspecies attraction above a critical value which depends on the vortex quantum number. For interspecies attraction just below this critical limit there is almost complete mixing of boson and fermion components. Such mixed and demixed states of a DBFM could be experimentally realized by varying an external magnetic field near a boson-fermion Feshbach resonance, which will result in a continuous variation of interspecies interaction.},
doi = {10.1103/PHYSREVA.75.053603},
journal = {Physical Review. A},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Mixing-demixing transition in one-dimensional mixtures of fermions and bosons is numerically investigated by changing various parameters such as number densities of each component, fermion-boson interactions, boson-boson interactions, and hopping energies. In most cases we found clear evidence of the mixing-demixing transitions and identified the roles of each microscopic parameter in the transitions. Several phase diagrams were obtained.
  • No abstract prepared.
  • We use a time-dependent dynamical mean-field-hydrodynamic model to study mixing-demixing in a degenerate fermion-fermion mixture (DFFM). It is demonstrated that with the increase of interspecies repulsion and/or trapping frequencies, a mixed state of a DFFM could turn into a fully demixed state in both three-dimensional spherically symmetric as well as quasi-one-dimensional configurations. Such a demixed state of a DFFM could be experimentally realized by varying an external magnetic field near a fermion-fermion Feshbach resonance, which will result in an increase of interspecies fermion-fermion repulsion, and/or by increasing the external trap frequencies.
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  • We calculate the spectrum of low-lying collective excitations in a mesoscopic cloud formed by a Bose-Einstein condensate and a spin-polarized Fermi gas as a function of the boson-fermion repulsions. The cloud is under isotropic harmonic confinement and its dynamics is treated in the collisional regime by using the equations of generalized hydrodynamics with inclusion of surface effects. For large numbers of bosons, we find that as the cloud moves towards spatial separation (demixing) with increasing boson-fermion coupling, the frequencies of a set of collective modes show a softening followed by a sharp upturn. This behavior permits a clear identification ofmore » the quantum phase transition. We propose a physical interpretation for the dynamical transition point in a confined mixture, leading to a simple analytical expression for its location.« less