Shining Light on Spin-Orbital Separation

We consider shining light on a quasi-one-dimensional Mott insulator exhibiting spin-orbital separation. The low-energy sector of such a compound can be described by a spin chain with additional orbital degrees of freedom. Starting from an initial state with a highly polarized orbital sector, depending on the direction and polarization of the light, different orbitals can be activated or deactivated to take part in the time evolution. By employing a combination of Floquet theory and numerical methods, we find that orbital polarization can be controlled by a chirped laser. We discuss our results in connection to pump-probe experiments on the one dimensional spin-orbital chain compound Sr2CuO3.