PolaritonZTopological Insulator (original) (raw)

2015, Physical Review Letters

Recent search for optical analogues of topological phenomena mainly focuses on mimicking the key feature of quantum Hall [1] and quantum spin Hall [2] effects (QHE and QSHE): edge currents protected from disorder. QHE relies on time-reversal symmetry breaking, which can be realised in photonic gyromagnetic crystals [3]. In the optical range, the weak magneto-optical activity may be replaced with helical design of coupled waveguides, converting light propagation into a timedependent perturbation [4]. Finally, optical QHE due to artificial gauge fields [5] was predicted in microcavity lattices. Here, we consider honeycomb arrays of microcavity pillars [6] as an alternative optical-frequency 2D topological insulator. We show that the interplay between the photonic spinorbit coupling natively present in this system [7, 8] and the Zeeman splitting of exciton-polaritons in external magnetic fields [9] leads to the opening of a non-trivial gap characterised by C = ±2 set of band Chern numbers and to the formation of topologically protected one-way edge states.