Light storage in a tripod medium as a basis for logical operations

A photon being a carrier of a polarization qubit is stored inside an atomic medium in the tripod configuration in the form of atomic excitations. Such stored information can be processed in the atomic memory and carried away by the released photon. An implementation is proposed of single qubit gates, e.g., phase, NOT, NOT and Hadamard, as well as for a two-qubit CNOT gate, operating on polarized photons and based on light storage.