You can find the online document here.
Publication appeared in Nature Communications
Experimental apparatus. A detailed schematic of experiment to search for a quaternionic contribution to phase shifts. (a) We generate photon pairs in a separable polarization state. One photon is used to herald while the other one is sent to our interferometers. (b) We couple a Sagnac interferometer into a Mach–Zehnder interferometer to search for non-commuting phases. We monitor the interference in the Mach–Zehnder interferometer as its phase ɳ is scanned. The output photons are detected using single-photon detectors D1 and D2. The detectors are connected to coincidence logic to herald single photons. Two phases are applied inside the Sagnac which we can controllably ‘turn on’ and ‘turn off’. The liquid crystal (LC) is controlled by applying voltage to it, and the negative index metamaterial (NIM) is mounted on a motorized translation stage so it can be ‘turned off’ by physically removing it from the interferometer.