  Kochen-Specker (KS) sets are key tools for proving some fundamental results
in quantum theory and also have potential applications in quantum information
processing. However, so far, their intrinsic complexity has prevented
experimentalists from using them for any application. The KS set requiring the
smallest number of contexts has been recently found. Relying on this simple KS
set, here we report an input state-independent experimental technique to
certify whether a set of measurements is actually accessing a preestablished
quantum six-dimensional space encoded in the transverse momentum of single
photons.
