Angular-Dependent Klein Tunneling in Photonic Graphene

Zhaoyang Zhang, Yuan Feng, Feng Li, Sergei Koniakhin, Changbiao Li, Fu Liu, Yanpeng Zhang, Min Xiao, Guillaume Malpuech, and Dmitry Solnyshkov Angular-Dependent Klein Tunneling in Photonic Graphene Phys. Rev. Lett. 129, 233901 https://doi.org/10.1103/PhysRevLett.129.233901

The Klein paradox consists in the perfect tunneling of relativistic particles through high potential barriers. It is responsible for the exceptional conductive properties of graphene. While in theory the perfect tunneling holds only for normal incidence, so far the angular dependence of the Klein tunneling and its strong variation with the barrier height were not measured experimentally. In this Letter, we capitalize on the versatility of atomic vapor cells with paraxial beam propagation and index patterning by electromagnetically induced transparency. We report the first experimental observation of perfect Klein transmission in a 2D photonic system (photonic graphene) at normal incidence and measure the angular dependence. Counterintuitively, but in agreement with the Dirac equation, we observe that the decay of the Klein transmission versus angle is suppressed by increasing the barrier height, a key result for the conductivity of graphene and its analogs.

Electrically tunable Berry curvature and strong light-matter coupling in liquid crystal microcavities with 2D perovskite

In this work, we present electrically tunable microcavity exciton-polariton resonances in a Rashba-Dresselhaus spin-orbit coupling field. For this, we have implemented an architecture of a photonic structure with a two-dimensional perovskite layer incorporated into a microcavity filled with nematic liquid crystal. Our work interfaces spinoptronic devices with electronics by combining electrical control over both the strong light-matter coupling conditions and artificial gauge fields. Science Advances 8, 40 (2022) (5 Oct 2022)

The optical Stern-Gerlach Deflection and Young’s experiment in the reciprocal space

Scientists for the first time demonstrated Young’s experiment for photons in the reciprocal space. Spin patterns corresponding to the persistent spin helix and the Stern-Gerlach experiment are realized in an optically anisotropic liquid crystal microcavity. By applying electric voltage across the microcavity, the liquid crystal molecules inside could be rotated in such a way that the light passing through the cavity was forced to change its internal state into right- and left-handed circular polarized components. EurekAlert!

Physical Review Letters, 127, 190401