Quantum breathers in a nonlinear Klein Gordon lattice

International audienceThe quantum modes of a nonlinear Klein Gordon lattice have been computed numerically (L.Proville, Phys. Rev. B 71, 104306 (2005)). The on-site nonlinearity has been found to lead toa phonon pairing and consequently some phonon bound states. In the present paper, the timedependent Wannier transform of these states is shown to exhibit a breather-like behavior, i.e., it is spatially localized and time-periodic. The typical time the lattice may sustain such breather states is studied as a function of the trapped energy and the intersite lattice coupling