So far, the development of micro-fabrication techniques in semiconductor materials has led to the engineering of high quality lattices of polariton microcavities. The main advantage of this system is that both the wave functions and the spectrum associated to the lattice hamiltonian can be directly measured in photoluminesce experiments In this work, taking advantage of the fine control in the engineering of polariton lattices, we experimentally investigate the topological transition that takes place when graphene is uniformly strained. We consider honeycomb lattices of polariton microcavities in which the hopping parameters change on the vertical direction only. This hopping control emulates the unidirectional strain in a real graphene and, consequently, modifies the band structure of the lattice leading to a topological transition. By scanning the frequencies of the luminescence light emitted by the honeycomb polariton lattices, we observe the different dispersion and diffusion features that this topological transition exhibits; such as the semi-Dirac dispersion and the vanishing of the so-called bearded edge state. The engineering of more elaborate strain patterns, or the application of strain to orbital bands appear as a very promising way to explore novel kinds of Dirac cones and band crossings.
 M. Milicevic et al. Phys. Rev. Lett. 118, 107403 (2017)
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 M. Milicevic et al. arXiv: 1807.08650.
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