Boson bunching is not maximized by indistinguishable particles

Boson bunching is among the most remarkable features of quantum physics. A celebrated example in optics Hong–Ou–Mandel effect, where two photons arises from a destructive interference between trajectories they both either cross beamsplitter or are reflected. This effect takes its roots indistinguishability identical photons. Hence, it generally admitted—and experimentally verified—that vanishes as soon can be distinguished, for example, when occupy distinct time bins have different polarizations. Here we disprove this alleged straightforward link and by exploiting recent finding theory matrix permanents. We exhibit family optical circuits such that into modes substantially boosted making them partially distinguishable via an appropriate polarization pattern. boosting already visible seven-photon interferometric process, observation phenomenon within reach current photonic technology. unexpected behaviour questions our understanding multiparticle grey zone indistinguishable bosons classical particles. common belief about boson bunching—fully utmost bunching—is theoretically disproved with seven seven-mode process. Enhanced could thus observed