Fast energy transfer mediated by multi-quanta bound states in a nonlinear quantum lattice

TL;DR

This paper investigates how energy transfer in a nonlinear quantum lattice is mediated by multi-quanta bound states, revealing conditions for rapid energy propagation and the formation of specific bound states that behave as independent quanta.

Contribution

It introduces a detailed analysis of multi-quanta bound states in a nonlinear quantum lattice, highlighting a critical nonlocal nonlinearity that enables fast, nonlinearity-insensitive energy transfer.

Findings

Energy localization on a site persists over time before delocalizing.

Increasing nonlocal nonlinearity speeds up energy propagation.

A critical nonlocal nonlinearity enables rapid, quantum-like energy transfer.

Abstract

By using a Generalized Hubbard model for bosons, the energy transfer in a nonlinear quantum lattice is studied, with special emphasis on the interplay between local and nonlocal nonlinearity. For a strong local nonlinearity, it is shown that the creation of v quanta on one site excites a soliton band formed by bound states involving v quanta trapped on the same site. The energy is first localized on the excited site over a significant timescale and then slowly delocalizes along the lattice. As when increasing the nonlocal nonlinearity, a faster dynamics occurs and the energy propagates more rapidly along the lattice. Nevertheless, the larger is the number of quanta, the slower is the dynamics. However, it is shown that when the nonlocal nonlinearity reaches a critical value, the lattice suddenly supports a very fast energy propagation whose dynamics is almost independent on the number of quanta. The energy is transfered by specific bound states formed by the superimposition of states involving v-p quanta trapped on one site and p quanta trapped on the nearest neighbour sites, with p=0,..,v-1. These bound states behave as independent quanta and they exhibit a dynamics which is insensitive to the nonlinearity and controlled by the single quantum hopping constant.