Theoretical design of quantum memory unit for under water quantum communication using electromagnetically induced transparency protocol in ultracold 87Rb atoms

In this paper, we present a theoretical proposal to realize Quantum Memory (QM) for storage of blue light pulses (420 nm) using Electromagnetically Induced Transparency (EIT). Three-level lambda-type EIT configuration system is solved in a fully quantum mechanical approach. Storing blue light has the potential application in the field of underwater quantum communication as it experiences less attenuation inside the sea water. Our model works by exciting the relevant transitions of Rb-87 atoms using a three-level lambda-type configuration in a Two-Dimensional Magneto-Optical Trap (2D MOT) with an optical cavity inside it. We have estimated Optical Depth inside the cavity (ODc) of 1.43 x 10(5), group velocity (v(g)) = 2.6 x 10(3) ms(-1), Delay Bandwidth Product (DBP) of 23 and maximum storage efficiency as 99% in our system.