Prof. De is an experimentalist in the areas of atomic-molecular-optical (AMO) physics with expertise in laser cooling and trapping of atoms & ions, degenerate quantum gasses, quantum optics and time & frequency metrology. His present research interests are (i) quantum metrology on ultra-stable optical reference that has applications in fundamental sciences and high-end technologies e.g. quantum communication; (ii) developing quantum-enhanced technologies; (iii) precision measurements for probing temporal constancy of dimensionless fundamental constants, geodesy, violation of Lorentz symmetry and (iv) studying quantum dynamics using trapped atoms/ ions.