Optical activity of noncentrosymmetric metals

We describe the phenomenon of optical activity of noncentrosymmetric metals in their normal and superconducting states. The found conductivity tensor contains the linear in wave vector off diagonal part responsible for the natural optical activity. Its value is expressed through the ratio of light frequency to the band splitting due to the spin-orbit interaction. The Kerr rotation of polarization of light reflected from the metal surface is calculated. In the additional file "Erratum" I've pointed out the sign error in arXiv:1001.2113 ( PRB v.81, 094525 (2010)) that leads to the wrong statement about the Kerr effect in light reflection from the surface of media without space parity.