Brief description of my current research

 

At the Stevens Institute of Technology, I am currently working on two different projects. First one is related to the experiment of entangled Airy beam photons for Quantum Key Distribution (QKD) through the complicated atmosphere: fog, heat scintillation, etc. There, we expect to see substantial advantages over normal Gaussian beams. Our previous results suggest the feasibility of using structured photons with exotic spatial and temporal modes for practical advantages in long-distance quantum communication, quantum imaging, quantum key distribution, light-sensitive biological applications, and so on. Beside the Airy modes, there exist a multitude of spatiotemproal modulations that can be similarly applied to quantum photonic signals to attain distinct advantages for various applications. The present experiment applies phase modulation directly to the generated photons, which induces loss and significantly reduces the photon production rate. This problem can be solved by using the lossless photon shaping technique. The second project is related to the experiment of spatial-mode selective Quantum Frequency Conversion (QFC) based on quasi-phase-matching (QPM) in a non-linear periodically-polled lithium niobate (PPLN) crystal. We are using spatial light modulators (SLM) to select the desired spatial mode. The sum-frequency generation (SFG) of the desired mode can be produced by PPLN crystal. Our preliminary results shows high internal conversion efficiency, as well as low crosstalk. This will have a potential for both classical and quantum demultiplexing applications.

 

 

A brief description of my Ph.D. research and its findings

 

I have investigated some specific paradigms in the area of coherent nonlinear atom-light interactions. The study of atom-light interaction and understanding of the underlying physics have made it possible to control and manipulate the optical properties of atomic media using coherent laser light. In this context, I have carried out extensive experimental and theoretical explorations of the role of atomic coherence for the realization of phenomena, such as Electromagnetically Induced Transparency (EIT) and slow light, with possible application in magnetometer and magneto-optic switch and the role of population oscillation in the realization of ultra-narrow resonance that cannot be attributed to EIT, which is known as Coherent Population Oscillation (CPO). I have also studied this new phenomenon for different polarizations of coupling and probe beams in a multi-level atomic system. We have shown that this long-lived CPO can be used as a light-storing device. We believe that this new phenomenon, insensitive to the inhomogeneous magnetic field, might also be useful for the photon pair generation and parametric amplification. I have also theoretically studied a scalable quantum network used to transfer quantum states as well as to create entanglement among nodes. By manipulating the intensities and phases of the control field, we can generate computationally useful quantum protocols. This model could be realized experimentally in optical nano-fiber or microcavities.

 

 

A brief description of my first post-doctoral research

 

My on-going research interest is in the field of ”Microwave and Radiowave frequency technologies, Quantum Optics and Quantum Information Science” and covers various fundamental and applied scientific questions. In particular, I want to understand, control and utilize practical atomic systems for quantum communication networks. In my career as a postdoc at the University of Oklahoma, I am working on two main projects: (1) sensing weak microwave (MW) electric field with Rydberg atoms in a vapor cell using Electromagnetically Induced Transparency (EIT) and (2) Cold Rydberg-blockaded atomic ensemble coupled to a high-finesse optical cavity. This method promises to have a wide range of applications, particularly in characterizing metamaterials and small MW circuits. We have shown for the first time that Rydberg atom EIT can be used to sense and image MW electric field with unprecedented precision. The current sensitivity limit is  3μVcm−1Hz−1/2. Our method utilizes EIT with Rydberg atoms in room temperature vapor cells to read out the effect that the MW electric field has on the Rydberg atoms. The method has the potential for high sensitivity ( pVcm−1Hz−1/2) and can be self-calibrated.To demonstrate the near-field subwavelength imaging, we investigated the MW electric field above a coplanar waveguide. We have been working on experimental and theoretical progress on a Rydberg-blockaded atomic ensemble coupled to a high-finesse optical cavity. We have analyzed the role that the Rydberg blockade mechanism can play in synthesizing non-classical states of light. We have shown that a cold atomic cloud can be transported into a high-finesse optical cavity by using a focus-tunable lens and that a Rydberg-blockaded collective state can be created inside the cavity. Recently, we have been trying to realize collective quantum states in this system and study the interesting dynamics of the correlated photon emission. Also, in collaboration with Dr. Saikat Ghosh (IITK) and Prof. Deepak Kumar (JNU), I theoretically studied the quantum routing of photons in an atom-cavity-fiber network.