See Google News for reports about his life, work, and death.
He was a Hindu physicist (interested in the science-religion interface) who has been nominated for the Nobel prize in physics 9 times. Among topics he has contributed to, we find the impressive list:
Optical coherence, Sudarshan-Glauber representation, V-A theory (with Marshak), Tachyons, Quantum Zeno effect, Open quantum system, Spin-statistics theorem, non-invariance groups, positive maps of density matrices, quantum computation among othersCzech readers could see that he was almost like Jára da Cimrman who discovered the V-A theory but was scooped or robbed by others etc.
There have been various controversies – for example, he has somewhat convincingly claimed that the 2005 physics Nobel prize which went to Glauber, Hall, and Hänsch (I remember the Harvard celebrations with Roy Glauber rather well) should have gone primarily to him. Similar claims have basically been made about his rights to get the 1979 Nobel prize which went to Glashow, Salam, and Weinberg.
I haven't studied his papers and the history in detail so I won't defend any appraisal of these claims. But I guess that he was a really good physicist who couldn't have been far from deserving these prizes.
As a Hindu, he should get reincarnated so things should be either settled through his Karma or in his next life. RIP – Reincarnate In Peace. Apologies to Kashyap (a Hindu TRF guest blogger) if I confused Hinduism with something else...