My research has been motivated by fundamental questions in cosmology such as physics in the early universe, and origins of the dark matter and cosmic acceleration. To deepen our understanding, a strong interaction between theory and observation is required. My interests revolve around the area of intersection between theoretical and observational studies. My current interests include cosmology using the cosmic microwave background (CMB), large-scale structure (LSS), reionization, and gravitational-wave (GW) direct detection. I have worked on non-Gaussian statistics to extract a map of lensing mass of the LSS from CMB data, to constrain reionization model and to improve the sensitivity of CMB data to the inflationary GWs. I have been involved in several ongoing and future CMB experiments as a theorist and data analyst such as Atacama Cosmology telescope, BICEP, Simons Observatory and LiteBIRD.