An experimentally feasible scheme for generating a 12-qubit hyperentangled
state via four photons, entangled in polarization, frequency and spatial mode,
is proposed. We study the nature of quantum non-locality of this hyperentangled
state by evaluating its violation degree to a Bell-type inequality, and find
that the result agrees well with quantum mechanics prediction while extremely
contradicts to the local realism constraint.Comment: 14 pages, 6 Postscript figure