  In heavy-ion collisions, quark-gluon plasma is likely to be produced with
sizable initial pressure anisotropy, which may leave an imprint on
electromagnetic observables. In order to model a strongly coupled anisotropic
plasma, we use the AdS/CFT correspondence to calculate the current-current
correlator of a weakly gauged U(1) subgroup of R symmetry in an N=4
super-Yang-Mills plasma with a (temporarily) fixed anisotropy. The dual
geometry, obtained previously by Janik and Witaszczyk, contains a naked
singularity which however permits purely infalling boundary conditions and
therefore the usual definition of a retarded correlator. We obtain numerical
results for the cases of wave vector parallel and orthogonal to the direction
of anisotropy, and we compare with previous isotropic results. In the
(unphysical) limit of vanishing frequency (infinite time) we obtain a vanishing
DC conductivity for any amount of anisotropy, but the anisotropic AC
conductivities smoothly approach the isotropic case in the limit of high
frequencies. We also discuss hard photon production from an anisotropic plasma
and compare with existing hard-loop resummed calculations.
