Magnetic-field-induced insulator-conductor transition in quenched lattice gauge theory

We study the electric conductivity of a quenched SU(2) lattice gauge theory in both confinement and deconfinement phases in the presence of constant external electromagnetic field. The conductivity is extracted from the current-current correlation functions using the Kubo formulas and the Maximal Entropy Method. We find that at small but nonzero temperatures in the confinement phase the external magnetic field induces nonzero electric conductivity along the direction of the magnetic field, transforming the system from an insulator into an anisotropic conductor. In the deconfinement phase the conductivity does not exhibit any sizable dependence on the magnetic field. (orig.)