  We propose a scheme to experimentally observe matter-wave interference in the
time domain, specifically in the arrival-time or the time-of-flight (TOF)
distribution for atomic BEC Schrodinger-cat state represented by superposition
of macroscopically separated wave packets in space. This is in contrast to
interference in space at a fixed time observed in reported BEC experiments. We
predict and quantify the quantum interference in the TOF distribution
calculated from the modulus of the quantum probability current density (rather
than the TOF distributions obtained from a purely classical or semi-classical
treatment in many reported experiments). The interference and hence the
coherence in the quantum TOF signal disappears in the large-mass limit. Our
scheme has the potential to probe the validity of various other theoretical
approaches (Phys. Rep. 338, 353 (2000)) of calculating the quantum arrival time
distribution.
