  When a single beam-splitter receives two beams of bosons described by Fock
states (Bose-Einstein condensates at very low temperatures), interesting
generalizations of the two-photon Hong-Ou-Mandel effect take place for larger
number of particles. The distributions of particles at two detectors behind the
beam splitter can be understood as resulting from the combination of two
effects, the spontaneous phase appearing during quantum measurement, and the
quantum angle. The latter introduces quantum "population oscillations", which
can be seen as a generalized Hong-Ou-Mandel effect, although they do not always
correspond to even-odd oscillations.
