All-optical spin switch

  • Control of the valence electron spin polarization through modification of singlet triplet mixing coefficients of pairs of rovibronic levels mixed by the spin-orbit interaction: prospects for an all-optical spin switch.
    • Molecular transitions are governed by the parity of the various states. In addition, only states of the same spin multiplicity combine with each other. Therefore, a transition from one singlet state to another is allowed, while a singlet to triplet transition is forbidden. This selection rule breaks down as the spin-orbit interaction becomes larger, as is the case for heavier atoms and molecules, but is quite strict for lighter molecules. We propose a novel quantum control scheme based on Autler-Townes splitting to create controllable linear combinations of singlet and triplet states, i.e dressed singlet-triplet window states. A five level molecular system interacting with three lasers is used to maximize upper level triplet state production by starting with a singlet ground state.