Generalized quantum XOR-gate for quantum teleportation and state   purification in arbitrary dimensional Hilbert spaces
  A generalization of the quantum XOR-gate is presented which operates in arbitrary dimensional Hilbert spaces. Together with one-particle Fourier transforms this gate is capable of performing a variety of tasks which are important for quantum information processing in arbitrary dimensional Hilbert spaces. Among these tasks are the preparation of Bell states, quantum teleportation and quantum state purification. A physical realization of this generalized XOR-gate is proposed which is based on non-linear optical elements. 
Gernot Alber, Aldo Delgado, Nicolas Gisin, Igor Jex