Figure 2: Experimental Implementation.

Our optical implementation to distinguish whether a pair of unitary gates commute or anti-commute with only a single copy of each gate. The photons for our experiment are generated in a separable polarization state using a Sagnac source (a). One photon is used as a herald, and the second is fed into the interferometer (b). The unitary gates in question are each implemented with three waveplates, and act on the polarization of single photons.