Satyendra Nath Bose was an Indian theoretical physicist and mathematician born in Kolkata. His most renowned work, Bose-Einstein statistics, a system of statistical quantum mechanics describing one of the ways in which identical particles may occupy a set of discrete energy levels. Subatomic particles that follow B-E statistics are known as bosons (named in his honour).
His work on the quantum theory of light led to the Bose-Einstein condensate; a state of matter in which separate atoms that are cooled close to absolute zero condense into a single quantum mechanical entity that can be described by a wave function on a near-macroscopic scale. This discovery is further detailed in “Theory of Bose-Einstein condensation in trapped gases” by Franco Dalfovo (1999).