IIT

To become a physics professor in IIT and any other TIER-1 colleges like IITs, 5NITs, DTU, BITS, and IIITH is not an easy task.
You need to have a PhD from country's most reputed college like like IISc Bangalore, IIT-Delhi, Bombay Kanpur. It's all about decorating your profile by doing some really good research papers. If you manage to prove your worth in your research area, and it impresses your Head of the Department; you can get a job as guest faculty. And you get paid for this. Actually, there's a high possibility of you getting chosen as an Asst. Prof of the same IIT from where you've applied for your Doctorate.
WHAT TO KEEP IN MIND:
1- You should be a pass-out from TIER1 colleges which were mentioned above.
2- Your profile is minutely checked, UG College, PG college and your CGPA should be &get;8
3- you need to impress the faculty and the H.O.D of the colleges where you want to teach even if you can't 'Teach' well, it doesn't matter unless you're highly qualified.

Hi Deepak,
The Indian Institutes of Technology (IITs) are autonomous public institutes of higher education, located in India.[1] They are governed by the Institutes of Technology Act, 1961 which has declared them as institutions of national importance alongside National Institutes of Technology[2] and lays down their powers, duties, and framework for governance etc.[3][4] The Institutes of Technology Act, 1961 lists twenty-three institutes (after the last amendment in 2016).[5] Each IIT is an autonomous institution, linked to the others through a common IIT Council, which oversees their administration. The Minister of Human Resource Development is the ex-officio Chairperson of IIT Council.[6] As of 2017, the total number of seats in all IITs is 11,032.[7]
The first IIT was set up in Kharagpur in 1951, and soon later in Bombay, Madras, Kanpur and Delhi. An IIT was then established in Guwahati in 1994. The University of Roorkee was converted to IIT Roorkee in 2001. Eight new IITs were set up in Gandhinagar, Jodhpur, Hyderabad, Indore, Patna, Bhubaneswar, Ropar, and Mandi in 2008-09. Around the same time the Institute of Technology, Banaras Hindu University was given IIT status. Another six new IITs in Tirupati, Palakkad, Dharwad, Bhilai, Goa and Jammu, approved through a 2016 bill amendment were established in 2015-16, along with the conversion of ISM Dhanbad to IIT.
All the best.

Hi Deepak,
The Indian Institutes of Technology (IITs) are autonomous public institutes of higher education, located in India.[1] They are governed by the Institutes of Technology Act, 1961 which has declared them as institutions of national importance alongside National Institutes of Technology[2] and lays down their powers, duties, and framework for governance etc.[3][4] The Institutes of Technology Act, 1961 lists twenty-three institutes (after the last amendment in 2016).[5] Each IIT is an autonomous institution, linked to the others through a common IIT Council, which oversees their administration. The Minister of Human Resource Development is the ex-officio Chairperson of IIT Council.[6] As of 2017, the total number of seats in all IITs is 11,032.[7]
The first IIT was set up in Kharagpur in 1951, and soon later in Bombay, Madras, Kanpur and Delhi. An IIT was then established in Guwahati in 1994. The University of Roorkee was converted to IIT Roorkee in 2001. Eight new IITs were set up in Gandhinagar, Jodhpur, Hyderabad, Indore, Patna, Bhubaneswar, Ropar, and Mandi in 2008-09. Around the same time the Institute of Technology, Banaras Hindu University was given IIT status. Another six new IITs in Tirupati, Palakkad, Dharwad, Bhilai, Goa and Jammu, approved through a 2016 bill amendment were established in 2015-16, along with the conversion of ISM Dhanbad to IIT.
All the best.