Ajay Kumar Sood (born 26 June 1951)[1] is an Indian physicist and researcher currently serving as the 4th Principal Scientific Adviser to the Government of India.

He holds 2 United States and 5 Indian patents,[3][4] and is known for his pioneering research findings[5] on graphene and nanotechnology.

[8] The Government of India honoured him in 2013, with the Padma Shri, the fourth highest civilian award, for his contributions to the fields of science and technology.

In 1973, he joined the Indira Gandhi Centre for Atomic Research, Kalpakkam, as a scientist where he worked till 1988.

[5] Sood has also been holding the position of the honorary professor at the Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru since 1993.

[3][5][6] Sood lives in Bengaluru, Karnataka state, India, associating himself with the Indian Institute of Science and the Jawaharlal Nehru Centre for Advanced Scientific Research.

[5][13][15] Sood, along with his team of scientists at the Indian Institute of Science, has done experiments on semiconductor superlattices, fullerenes, solid C60, C70[16] and single walled carbon nanotubes and reported to have unearthed new concepts on optical phonons.

[5][17][18] He was successful in exciting squeezed phonon states in KTa03 crystals, reported to be for the first time, by using femtosecond laser pulses and employing impulsive simulated Raman scattering.

[5][20] Sood has also experimented with soft condensed matter like micelle composed viscoelastic gels which establish a deterministic spatiotemporal chaotic dynamics in the nonlinear flow regime.

[27] Sood has also served on the scientific advisory committee to the Prime Minister of India from 2009 to 2014,[13] and is the Chairman of the National Physical Laboratory, New Delhi.