Dear Athira, the following is the list of post graduation courses at IIST. https://www.iist.ac.in/academics/curricula

Most of the eligibility criteria is that the candidate should have completed B.E/B.Tech or a M.Sc/MS for specialisation in relavent courses. Unfortunately a graduation in Physics is no where mentioned as the eligibility criteria. Here is the link for your confirmation: https://www.iist.ac.in/admissions/postgraduate/regular