Coherent generation and manipulation of stationary light pulses encoded in degrees of freedom of polarization and orbital angular momentum

Abstract

We propose a double-$\mathsf{M}$ system of cold atoms for realizing the reversible storage and manipulation of signal fields encoded in degrees of freedom (DOFs) of polarization and orbital angular momentum (OAM). By employing two pairs of counterpropagating controlling fields, we show that the system exhibits dark state polaritons relating to the polarization and propagation direction of the light fields. Through the active operation of the controlling fields in time, stationary light pulses with polarizations and OAM information can be generated due to the tight coupling and balanced competition between the retrieved signal fields, and can be manipulated coherently and all-optically. Another advantage of our proposed scheme is that the two polarization components of the signal field can be decoupled and thus be independently retrieved from the atomic ensemble, and then the scheme can be employed to realize polarization-dependent beam splitting. Such a multiple DOF-dependent scheme could pave the way toward quantum nonlinear optics without a cavity, and could greatly enhance the tunability and capacity for both classical and quantum information processing.