Figure 4: Quantifying the contribution of looped trajectories through the normalized Sorkin parameter, κ.

(a) Shows numerical and experimental results, for a sample with w=200 nm, h=100 μm and p=4.6 μm and an illuminating field consisting of heralded single-photons at a wavelength of 810 nm. The experimental points are obtained by measuring κ at different peaks of the interference patterns shown in Fig. 3. (b) Shows theoretical and experimental evidence at the central maximum for different widths and for various wavelengths for an attenuated laser diode, in this case the contributions from looped paths makes the κ different from zero. (c) Shows a situation in which looped trajectories are not enhanced and consequently κ is almost zero. These results confirm that the strengths of looped trajectories can be controlled by engineering the size of the slits and the wavelength of the illuminating field. These values of κ were measured at the center of the interference pattern. The error bars represent the standard deviation over the ensemble of measurements. The labels x and y indicate the polarization state of the incident light.