  The novel experimental realization of three-state optical quantum systems is
presented. We use the polarization state of biphotons,propagating in single
frequency- and spatial mode, to generate an arbitrary qutrits. In particular
the specific sequence of states that are used in the extended version of BB84
quantum key distribution protocol was generated and tested. We experimentally
verify the orthogonality of the 12 basic states and demonstrate the ability of
switching between them. The tomography procedure is applied to reconstruct the
density matrices of generated states.
