AdS plane waves and entanglement entropy
  AdS plane waves describe simple backgrounds which are dual to anisotropically excited systems with energy fluxes. Upon dimensional reduction, they reduce to hyperscaling violating spacetimes: in particular, the $AdS_5$ plane wave is known to exhibit logarithmic behavior of the entanglement entropy. In this paper, we carry out an extensive study of the holographic entanglement entropy for strip-shaped subsystems in AdS plane wave backgrounds. We find that the results depend crucially on whether the strip is parallel or orthogonal to the energy current. In the latter case, we show that there is a phenomenon analogous to a phase transition. 
K. Narayan, Tadashi Takayanagi, Sandip P. Trivedi
hep-th