  Controlling the pump beam transverse profile in multimode Hong-Ou-Mandel
interference, we generate a ''localized" two-photon singlet state, in which
both photons propagate in the same beam. This type of multi-photon singlet beam
may useful in quantum communication to avoid decoherence. We show that although
the photons are part of the same beam, they are never in the same plane wave
mode, which is characterized by spatial antibunching behavior in the plane
normal to the propagation direction.
