2017/05/31 by Jiho Noh, Sheng Huang, Kevin Chen +1 · 1 citation
Physics and Astronomy · #physics.optics #cond-mat.mes-hall #cond-mat.quant-gas
paper · pdf · doi:10.1103/physrevlett.120.063902
published as Phys. Rev. Lett. 120, 063902 (2018)
arxiv created 2017/05/31 · arxiv updated 2018/02/12
We experimentally demonstrate topological edge states arising from the valley-Hall effect in twodimensional honeycomb photonic lattices with broken inversion symmetry. We break inversion symmetry by detuning the refractive indices of the two honeycomb sublattices, giving rise to a boron nitride-like band structure. The edge states therefore exist along the domain walls between regions of opposite valley Chern numbers. We probe both the armchair and zig-zag domain walls and show that the former become gapped for any detuning, whereas the latter remain ungapped until a cutoff is reached. The valley-Hall effect provides a new mechanism for the realization of time-reversal invariant photonic topological insulators.