  We propose an interferometric scheme for generating the totally antisymmetric
state of $N$ identical bosons with $N$ internal levels (generalized singlet).
This state is a resource for various problems with dramatic quantum advantage.
The procedure uses a sequence of Fourier multi-ports, combined with coincidence
measurements filtering the results. Successful preparation of the generalized
singlet is confirmed when the $N$ particles of the input state stay separate
(anti-bunch) on each multiport. The scheme is robust to local lossless noise
and works even with a totally mixed input state.
