Phonon-like excitations in the two-state Bose-Hubbard model
Phonon-like excitations in the two-state Bose-Hubbard model
The spectrum of phonon-like collective excitations in the system of Bose-atoms in optical lattice (more generally, in the system of quantum particles described by the Bose-Hubbard model) is investigated. Such excitations appear due to displacements of particles with respect to their local equilibrium positions. The two-level model taking into account …