skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials

Abstract

We study the spontaneous symmetry breaking (SSB) of a superfluid Bose-Fermi (BF) mixture in a double-well potential (DWP). The mixture is described by the Gross-Pitaevskii equation (GPE) for the bosons, coupled to an equation for the order parameter of the Fermi superfluid, which is derived from the respective density functional in the unitarity limit (a similar model applies to the BCS regime, too). Straightforward SSB in the degenerate Fermi gas loaded into a DWP is impossible, as it requires an attractive self-interaction, and the intrinsic nonlinearity in the Fermi gas is repulsive. Nonetheless, we demonstrate that the symmetry breaking is possible in the mixture with attraction between fermions and bosons, like {sup 40}K and {sup 87}Rb. Numerical results are represented by dependencies of asymmetry parameters for both components on particle numbers of the mixture, N{sub F} and N{sub B}, and by phase diagrams in the (N{sub F},N{sub B}) plane, which displays regions of symmetric and asymmetric ground states. The dynamical picture of the SSB, induced by a gradual transformation of the single-well potential into the DWP, is reported too. An analytical approximation is proposed for the case when the GPE for the boson wave function may be treated by meansmore » of the Thomas-Fermi (TF) approximation. Under a special linear relationship between N{sub F} and N{sub B}, the TF approximation allows us to reduce the model to a single equation for the fermionic function, which includes competing repulsive and attractive nonlinear terms. The latter one directly displays the mechanism of the generation of the effective attraction in the Fermi superfluid, mediated by the bosonic component of the mixture.« less

Authors:
 [1];  [2]; ;  [3]
  1. Instituto de Fisica Teorica, Universidade Estadual Paulista, 01.140-070 Sao Paulo, Sao Paulo (Brazil)
  2. Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)
  3. Consiglio Nazionale delle Ricerche and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Unita di Padova, Dipartimento di Fisica 'Galileo Galilei', Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy)
Publication Date:
OSTI Identifier:
21408887
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 81; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.81.053630; (c) 2010 The American Physical Society; Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APPROXIMATIONS; BOSONS; DENSITY FUNCTIONAL METHOD; EQUATIONS; FERMI GAS; FERMIONS; GROUND STATES; MIXTURES; NONLINEAR PROBLEMS; ORDER PARAMETERS; PHASE DIAGRAMS; POTASSIUM 40; POTENTIALS; RUBIDIUM 87; SUPERFLUIDITY; SYMMETRY; SYMMETRY BREAKING; THOMAS-FERMI MODEL; WAVE FUNCTIONS; ATOMIC MODELS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; CALCULATION METHODS; DIAGRAMS; DIMENSIONLESS NUMBERS; DISPERSIONS; ELECTRON CAPTURE RADIOISOTOPES; ENERGY LEVELS; FUNCTIONS; INFORMATION; INTERMEDIATE MASS NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LIGHT NUCLEI; MATHEMATICAL MODELS; NANOSECONDS LIVING RADIOISOTOPES; NUCLEI; ODD-EVEN NUCLEI; ODD-ODD NUCLEI; POTASSIUM ISOTOPES; RADIOISOTOPES; RUBIDIUM ISOTOPES; VARIATIONAL METHODS; YEARS LIVING RADIOISOTOPES

Citation Formats

Adhikari, S K, Malomed, B A, Salasnich, L, and Toigo, F. Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials. United States: N. p., 2010. Web. doi:10.1103/PHYSREVA.81.053630.
Adhikari, S K, Malomed, B A, Salasnich, L, & Toigo, F. Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials. United States. https://doi.org/10.1103/PHYSREVA.81.053630
Adhikari, S K, Malomed, B A, Salasnich, L, and Toigo, F. 2010. "Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials". United States. https://doi.org/10.1103/PHYSREVA.81.053630.
@article{osti_21408887,
title = {Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials},
author = {Adhikari, S K and Malomed, B A and Salasnich, L and Toigo, F},
abstractNote = {We study the spontaneous symmetry breaking (SSB) of a superfluid Bose-Fermi (BF) mixture in a double-well potential (DWP). The mixture is described by the Gross-Pitaevskii equation (GPE) for the bosons, coupled to an equation for the order parameter of the Fermi superfluid, which is derived from the respective density functional in the unitarity limit (a similar model applies to the BCS regime, too). Straightforward SSB in the degenerate Fermi gas loaded into a DWP is impossible, as it requires an attractive self-interaction, and the intrinsic nonlinearity in the Fermi gas is repulsive. Nonetheless, we demonstrate that the symmetry breaking is possible in the mixture with attraction between fermions and bosons, like {sup 40}K and {sup 87}Rb. Numerical results are represented by dependencies of asymmetry parameters for both components on particle numbers of the mixture, N{sub F} and N{sub B}, and by phase diagrams in the (N{sub F},N{sub B}) plane, which displays regions of symmetric and asymmetric ground states. The dynamical picture of the SSB, induced by a gradual transformation of the single-well potential into the DWP, is reported too. An analytical approximation is proposed for the case when the GPE for the boson wave function may be treated by means of the Thomas-Fermi (TF) approximation. Under a special linear relationship between N{sub F} and N{sub B}, the TF approximation allows us to reduce the model to a single equation for the fermionic function, which includes competing repulsive and attractive nonlinear terms. The latter one directly displays the mechanism of the generation of the effective attraction in the Fermi superfluid, mediated by the bosonic component of the mixture.},
doi = {10.1103/PHYSREVA.81.053630},
url = {https://www.osti.gov/biblio/21408887}, journal = {Physical Review. A},
issn = {1050-2947},
number = 5,
volume = 81,
place = {United States},
year = {Sat May 15 00:00:00 EDT 2010},
month = {Sat May 15 00:00:00 EDT 2010}
}