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Some selected highlights of research work at IIT Patna

Two Dimensional Magneto Optical Trap (2D MOT) for Quantum memory applications 

In this work, we propose a novel technique for slow light experiments using electromagnetically induced transparency using a two-dimensional magneto optical trap (2D-MOT). A compact 2D-MOT design efficient for quantum memory applications with adjustable optical depth (OD) is proposed. We estimated the OD for our 2D-MOT setup and found that light group velocities as low as 1.4 m/s can be attained. Our design for 2D-MOT allows precise control and optimization of the OD such that high storage efficiencies could also be achieved. With our design, it is possible to obtain a delay bandwidth product of 163, which is very high in comparison to previously obtained values.


Ultracold Rydberg atoms for efficient storage of terahertz frequency signals using electromagnetically induced transparency 

Quantum communication with terahertz (THz) frequency signals has many advantages like reduced attenuation and scintillation effects in certain atmospheric conditions along with very high level of data security. In this work, we propose a scheme to realize Quantum Memory (QM) for efficient storage of terahertz (THz) frequency signals using Electromagnetically Induced Transparency (EIT) in an ultracold atomic medium of 87Rb Rydberg atoms prepared in a Two Dimensional Magneto Optical Trap (2D-MOT). The uniqueness of our scheme lies in the choice of the energy levels involved in the EIT process, all three of which have been chosen to be the Rydberg levels (enabling signal beam to be in THz) in a lambda type arrangement. This first of its kind proposal reveals that atomic media are a potential candidate for devising QMs which can store THz frequency signals. We have estimated that the Optical Depth (OD) in our scheme can reach a very high value of 690, very high maximum obtainable storage efficiency (η) of ∼99%, the group velocity () can be as low as 5.07 × 103 m/s, and the Delay Bandwidth Product (DBP) can be as high as 9.5. All of these estimates emphasize the feasibility of our scheme as a QM device for efficient storage of THz pulses.

Broadband Quantum Memory Using Electromagnetically Induced Transparency in Atomic Medium 

In this work, we describe a theoretical design for the realization of a high capacity (bandwidth) atomic Quantum memory based on Wavelength Division Multiplexing and Electromagnetically Induced Transparency in adjacently placed 87Rb vapoucells. Magnetic fields produced by Helmholtz coils are used to tailor the atomic energy levels in the vapour cells and hence storage of various probe signals of different wavelengths becomes possible. We give a detailed description of the proposed experimental set up. We have estimated a very high bandwidth of 500MHz for our design with a Delay Bandwidth Product of approximately 35. Our prototype design is for storing 5 dierent wavelength probe pulses which could be extended to larger values in principle.

Experimental Set up for Electromagnetically Induced Transperancy (EIT), Structured EIT, Rydberg atoms

Pump Probe set up for EIT in ladder configuration for Rb atomic gas

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