Light-Induced Mirror Symmetry Breaking and Charge Transport

We propose that light can break mirror symmetries and combining symmetries with a uniform time translation, and their breaking is characterized by an off-diagonal charge conductivity. Taking periodically driven graphene as an example, we show that mirror symmetries about the $xz$ and $yz$ planes and the combining symmetries, the symmetries of combinations of the mirror operations about these planes and a uniform time translation, can be broken by linearly or circularly polarized light. We also show that this symmetry breaking induces the time-averaged off-diagonal symmetric or antisymmetric charge conductivity in a nonequilibrium steady state with linearly or circularly, respectively, polarized light. Our results are experimentally testable in pump-probe measurements. This work will pave the way for controlling mirror symmetries via light and utilizing the light-induced mirror symmetry breaking.