  In an exciting experiment by MIT's group (Science 275, 637 (1997)), clear
interference fringes were observed for two initially independent Bose
condensates in dilute gas. Presently, there are two different theories
(measurement-induced interference theory and interaction-induced interference
theory) which can both explain MIT's experimental results. Based on our
interaction-induced interference theory, we consider the evolution of the
density-density correlation after the releasing of a double-well potential
trapping two independent Bose condensates. Based on the interaction-induced
interference theory, we find that the interference fringes in the
density-density correlation exhibit a behavior of emergence and disappearance
with the development of time. We find essential difference for the
density-density correlation based on interaction-induced interference theory
and measurement-induced interference theory, and thus we suggest the
density-density correlation to experimentally reveal further the interference
mechanism for two initially independent Bose condensates.
