  We investigate the quantum interference between two Bose-Einstein condensates
formed in small atomic samples composed of a few thousand atoms both by
imposing Bose broken gauge symmetry from the outset and also using an explicit
model of atomic detection. In the former case we show that the macroscopic wave
function collapses and revives in time, and we calculate the characteristic
times for current experiments. Collapses and revivals are also predicted in the
interference between two Bose-Einstein condensates which are initially in Fock
states, a relative phase between the condensates being established via atomic
detections corresponding to uncertainty in the number difference between them.
