15,100 research outputs found
Mott states under the influence of fermion-boson conversion: invasion of superfluidity
I study the influence of fermion-boson conversion near Feshbach resonances on
Mott states of Cooper pairs and demonstrate possible invasion of superfluidity.
The quantum dynamics of Fermi-Bose gases is studied using both an effective
coupled quantum rotor Hamiltonian and a coupled XXZ
XXZ spin Hamiltonian. I also point out two distinct branches of
collective modes in superfluid states, one of which involves anti-symmetric
phase oscillations in fermionic and bosonic channels and is {\em always} gapped
because of fermion-boson conversion.Comment: 5 pages; typos correcte
A Note on Pseudo-Hermitian Systems with Point Interactions and Quantum Separability
We study the quantum entanglement and separability of Hermitian and
pseudo-Hermitian systems of identical bosonic or fermionic particles with point
interactions. The separability conditions are investigated in detail.Comment: 6 page
Resonance Scattering in Optical Lattices and Molecules: Interband versus Intraband Effects
We study the low-energy two-body scattering in optical lattices with all
higher-band effects included in an effective potential, using a renormalization
group approach. As the potential depth reaches a certain value, a resonance of
low energy scattering occurs even when the negative s-wave scattering length
is much shorter than the lattice constant. These resonances can be
mainly driven either by interband or intraband effects or by both, depending on
the magnitude of . Furthermore the low-energy scattering matrix in optical
lattices has a much stronger energy-dependence than that in free space. We also
investigate the momentum distribution for molecules when released from optical
lattices.Comment: 4 figures, version accepted for publication in PR
Estimates of Effective Hubbard Model Parameters for C20 isomers
We report on an effective Hubbard Hamiltonian approach for the study of
electronic correlations in C isomers, cage, bowl and ring, with quantum
Monte Carlo and exact diagonalization methods. The tight-binding hopping
parameter, , in the effective Hamiltonian is determined by a fit to density
functional theory calculations, and the on-site Coulomb interaction, , is
determined by calculating the isomers' affinity energies, which are compared to
experimental values. For the C fullerene cage we estimate eV and . The resulting
effective Hamiltonian is then used to study the shift of spectral peaks in the
density of states of neutral and one-electron-doped C isomers. Energy
gaps are also extracted for possible future comparison with experiments.Comment: 6 pages, 5 figure
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