JC Eilbeck and F Palmero (pdf copy 290 kb.)
A quantum breather on a translationally invariant one-dimensional anharmonic lattice is an extended Bloch state with two or more particles in a strongly correlated state. In this Letter we study a periodic lattice containing bosons described by the quantum discrete nonlinear Schrödinger equation (QDNLS), a quantum version of the discrete nonlinear Schrödinger equation, also known as the boson Hubbard model. We discuss several effects that break the lattice symmetry and lead to spatial localization of the breather.
Phys. Lett. A, 331(3-4):201-208, 2004, doi:10.1016/j.physleta.2004.08.060