Hi dear,

           You can pursue Mtech in QROR from ISI Kolkata. The eligibility criteria is that you must have cleared Bachelors of Technology or Bachelors of Engineering from reputed university. You also possess a good knowledge of Mathematics. 

To get admission in ISI, Kolkata one needs to clear GATE exam with good marks or their entrance exam with the good marks (if you haven't appeared for GATE). Then you will be called for interview. Final selection will be based on marks of entrance exam and interview marks.

All the best