Decoherence from internal dynamics in macroscopic matter-wave interferometry

Usually, decoherence is generated from the coupling with an outer environment. However, a macroscopic object generically possesses its own environment in itself, namely the complicated dynamics of internal degrees of freedom. We address a question: when and how the internal dynamics decohere interference of the center of mass motion of a macroscopic object. We will show that weak localization of a macroscopic object in disordered potentials can be destroyed by such decoherence.