Electromagnetically Induced Flux Lattices for 2D Photon Gases

The intense interest in topological states of matter has triggered an outpouring of effort to develop artificial gauge fields for ultracold atomic gases, where access to extraordinary control provides a promising route to the creation of synthetic materials on-demand. However, engineering \textit{scalable} magnetic fields for neutral particles has proven difficult, resulting in either low flux densities or small system sizes. A new, scalable approach to creation of high flux densities for neutral atoms employs a so-called ``optical flux lattice,'' which is a spinor lattice of berry-phase vortices [1]. Here we discuss an extension of this idea to photonic systems: using a coherently driven atomic ensemble, we modify the optical response of a near-degenerate cavity to mimick an effective optical flux lattice for photonic polarization states. This enables us to engineer photonic Bloch-bands with non-zero Chern number, giving rise to chiral edge-modes in the presence of an additional potential. The single particle bulk- and edge-dispersion relations may be directly probed in cavity transmission. Combined with interactions, the proposed hybrid system presents an ideal tool to study strongly correlated photon states. \\[4pt] [1] N. R. Cooper, Phys. Rev. Lett. 106, 175301 (2011).