Thermalization of Atom-Molecule Bose Gases in a Double-Well Potential

We study the non-equiliribium dynamics of atom-molecule Bose gases in a double-well potential. In this system, the internal atom-molecule tunneling has significant influence on the dynamics. We investigate the periodicity of dynamics by studying the level statistics of the quantum system. We find that chaotic energy eigenstates arise from the competition between the interwell and the atom-molecule internal tunnelings. Furthermore, we show that the physical quantities relax to the microcanonical averages in the full-quantum dynamics when the system is chaotic. This thermalization is caused by the verification of eigenstate thermalization hypothesis (ETH). We show numerically that the onset of ETH occurs simultaneously with that of chaos. In addition, we show that the energy eigenstates become to be exponentially localized states simultaneously with the onset of chaos.