General relativity and the cuprates

We add a periodic potential to the simplest gravitational model of a superconductor and compute the optical conductivity. In addition to a superfluid component, we find a normal component that has Drude behavior at low frequency followed by a power law fall-off. Both the exponent and coefficient of the power law are temperature independent and agree with earlier results computed above T-c. These results are in striking agreement with measurements on some cuprates. We also find a gap Delta = 4.0 T-c, a rapidly decreasing scattering rate, and missing spectral weight at low frequency, all of which also agree with experiments.