The evolution of atomic matter waves inside an atom fiber

A phenomenological description of time evolution of atomic matter waves inside a spiral shaped atomic-wave guide is presented in this report. We study three related topics: (i) the effective Hamiltonian and the time-development equation governing the matter waves; (ii) wavefunctions describing the matter waves in the noncoplanar atom guide; (iii) showing that such wavefunctions obtained is just the eigenstates of the atomic momentum operator. It is believed that both the idea and the results presented here may have relevance to some fundamental problems of atom optics.