Storing vector-vortex states of light in an intra-atomic frequency-comb quantum memory*

Photons are a prominent candidate for long-distance quantum communication and quantum information processing. Certain quantum information processing tasks require storage and faithful retrieval of single photons, preserving the internal states of the photons. Here we propose a method to store orbital angular momentum and polarization states of light which facilitates the storage of the vector-vortex states in the intra-atomic frequency-comb-based quantum memory. We show that an atomic ensemble with two intra-atomic frequency combs corresponding to △m = ±1 transitions of similar frequency is sufficient for a robust and efficient quantum memory for vector-vortex states of light. As an example, we show that Cs and Rb atoms are good candidates for storing these internal modes of light.