Chaotic delocalization of two interacting particles in the classical Harper model
Résumé
We study the problem of two interacting particles in the
classical Harper model in the regime when
one-particle motion is absolutely bounded
inside one cell of periodic potential.
The interaction between particles breaks integrability
of classical motion leading to emergence of Hamiltonian
dynamical chaos. At moderate interactions
and certain energies above the mobility edge
this chaos leads to a chaotic propulsion of two particles
with their diffusive spreading over the whole space
both in one and two dimensions.
At the same time the distance between particles remains
bounded by one or two periodic cells
demonstrating appearance of
new composite quasi-particles called chaons.
The effect of chaotic delocalization
of chaons is shown to be rather
general being present for Coulomb and short range interactions.
It is argued that such delocalized chaons can be
observed in experiments with cold atoms and ions
in optical lattices.