, British India) is an India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

n-born American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 theoretical physicist, notable for his contribution to quantum field theory

Quantum field theory

Quantum field theory provides a theoretical framework for constructing quantum mechanical models of systems classically parametrized by an infinite number of dynamical degrees of freedom, that is, fields and many-body systems. It is the natural and quantitative language of particle physics and...

.

Education and career

Gupta received his Ph.D. from the University of Cambridge

University of Cambridge

The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...

, and worked at the Institute for Advanced Study in Dublin during 1948–49. From 1951 to 1953 he served as ICI Fellow at the University of Manchester

University of Manchester

The University of Manchester is a public research university located in Manchester, United Kingdom. It is a "red brick" university and a member of the Russell Group of research-intensive British universities and the N8 Group...

. In 1953 Gupta joined as a visiting professor at Purdue University

Purdue University

Purdue University, located in West Lafayette, Indiana, U.S., is the flagship university of the six-campus Purdue University system. Purdue was founded on May 6, 1869, as a land-grant university when the Indiana General Assembly, taking advantage of the Morrill Act, accepted a donation of land and...

 and remained there until 1956. From 1956, he served as a professor at Wayne State University

Wayne State University

Wayne State University is a public research university located in Detroit, Michigan, United States, in the city's Midtown Cultural Center Historic District. Founded in 1868, WSU consists of 13 schools and colleges offering more than 400 major subject areas to over 32,000 graduate and...

 in Detroit.

Work

Gupta introduced in 1950, simultaneously and independently of Konrad Bleuler

Konrad Bleuler

Konrad Bleuler was a Swiss physicist who worked in the field of theoretical particle physics and quantum field theory. He is known for his work on the quantisation of the photon, the Gupta–Bleuler formalism.-Education and career:Bleuler was born in Herzogenbuchsee, Switzerland on 23 September 1912...

, the Gupta–Bleuler quantization

Quantization (physics)

In physics, quantization is the process of explaining a classical understanding of physical phenomena in terms of a newer understanding known as "quantum mechanics". It is a procedure for constructing a quantum field theory starting from a classical field theory. This is a generalization of the...

 of the quantum electrodynamics

Quantum electrodynamics

Quantum electrodynamics is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved...

 (QED) that takes the covariant Lorenz gauge condition

Lorenz gauge condition

In electromagnetism, the Lorenz gauge or Lorenz gauge condition is a partial gauge fixing of the electromagnetic vector potential. The condition is that \partial_\mu A^\mu=0...

 on an indefinite metric in Hilbert space

Hilbert space

The mathematical concept of a Hilbert space, named after David Hilbert, generalizes the notion of Euclidean space. It extends the methods of vector algebra and calculus from the two-dimensional Euclidean plane and three-dimensional space to spaces with any finite or infinite number of dimensions...

 of states realized. From it came some of the first attempts, to derive the equations of general relativity

General relativity

General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

 from quantum field theory

Quantum field theory

Quantum field theory provides a theoretical framework for constructing quantum mechanical models of systems classically parametrized by an infinite number of dynamical degrees of freedom, that is, fields and many-body systems. It is the natural and quantitative language of particle physics and...

 for a massless spin two particle (graviton

Graviton

In physics, the graviton is a hypothetical elementary particle that mediates the force of gravitation in the framework of quantum field theory. If it exists, the graviton must be massless and must have a spin of 2...

). Similar work has also led Robert Kraichnan

Robert Kraichnan

Robert Harry Kraichnan , a resident of Santa Fe, New Mexico, was an American theoretical physicist best known for his work on the theory of fluid turbulence.- Life :...

 in the 1940s (not published until 1955) and later in the 1960s, by Richard Feynman

Richard Feynman

Richard Phillips Feynman was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics...

 and Steven Weinberg

Steven Weinberg

Steven Weinberg is an American theoretical physicist and Nobel laureate in Physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and electromagnetic interaction between elementary particles....

. Later he worked in various areas of quantum field theory and elementary particle physics

Particle physics

Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...

, including quantum chromodynamics

Quantum chromodynamics

In theoretical physics, quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons . It is the study of the SU Yang–Mills theory of color-charged fermions...

 and Quarkonium

Quarkonium

In particle physics, quarkonium designates a flavorless meson whose constituents are a quark and its own antiquark. Examples of quarkonia are the J/ψ meson and the meson...

.