Quantum phases of atomic bosonfermion mixtures in optical lattices
Abstract
The zerotemperature phase diagram of a binary mixture of bosonic and fermionic atoms in a onedimensional optical lattice is studied in the framework of the BoseFermiHubbard model. By exact numerical solution of the associated eigenvalue problems, ground state observables and the response to an external phase twist are evaluated. The stiffnesses under phase variations provide measures for the boson superfluid fraction and the fermionic Drude weight. Several distinct quantum phases are identified as functions of the strength of the repulsive bosonboson and the bosonfermion interactions. In addition to the bosonic Mottinsulator phase, two other insulating phases are found, where both the bosonic superfluid fraction and the fermionic Drude weight vanish simultaneously. One of these doubleinsulator phases exhibits a crystalline diagonal longrange order, while the other is characterized by spatial separation of the two species.
 Publication:

Physical Review A
 Pub Date:
 February 2004
 DOI:
 10.1103/PhysRevA.69.021601
 arXiv:
 arXiv:condmat/0310114
 Bibcode:
 2004PhRvA..69b1601R
 Keywords:

 03.75.Lm;
 03.75.Ss;
 03.75.Kk;
 73.43.Nq;
 Tunneling Josephson effect BoseEinstein condensates in periodic potentials solitons vortices and topological excitations;
 Degenerate Fermi gases;
 Dynamic properties of condensates;
 collective and hydrodynamic excitations superfluid flow;
 Quantum phase transitions;
 Condensed Matter  Statistical Mechanics
 EPrint:
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