The celebrated Dirac equation governs numerous relativistic effects that are far beyond our intuitive perception of nature. Unfortunately, most of these phenomena occur only under most extreme conditions, which lie far beyond the reach of current experimental capabilities.
We show with our work that lattices of evanescently coupled waveguides [J. Phys. B 43, 163001 (2010)] are a versatile platform for testing relativistic theories in photonic table-top experiments. Following the discovery of a striking similarity between light evolution in appropriately designed photonic lattice to dynamics arising from the Dirac equation, we were able to show in classical experiments various peculiar effects such as Zitterbewegung of free electrons [Phys. Rev. Lett. 105, 143902 (2010)], pair creation and vaccum Rabi flops [Phys. Rev. Lett. 109, 110401 (2012)], massless Dirac particles [Phys. Rev. Lett. 109, 023602 (2012)], relativistic random mass flips [Nature Commun. 4, 1368 (2013)], ultrastrong pseudo-magnetic fields [Nature Photon. 7, 153 (2013)], and the realization of type-II Dirac points [Nature Commun. 11, 2074 (2020)].
Recently, our advanced understanding of integrated waveguide circuits even allowed us the first emulation of an unphysical phemomenon that is conventionally regarded to be un-physical: charge conjugation violation of Majorana fermions [Optica 2, 454 (2015)].