# A sincere tribute to E.C.G Sudarshan's phenomenal contribution toward quantum theory of optical coherence

## TL;DR

This paper honors E.C.G. Sudarshan's pioneering work in quantum optics, explaining his mathematical contributions and their significance in understanding the quantum properties of light.

## Contribution

It provides a detailed, rigorous explanation of Sudarshan's original work on the equivalence of semi-classical and quantum descriptions of light.

## Key findings

- Clarifies the mathematical foundation of optical coherence
- Highlights applications in various physics problems
- Reinforces the significance of Sudarshan's contributions

## Abstract

The diagonal representation and optical equivalence theorem are the E. C. G. Sudarshan's mid 20th century adventures in non-classical optics. It basically deals with a quantum mechanical description of photons to explain the quantum properties of light. Inspired by Sudarshan's pioneering work we try to explain the every minute mathematical details of his paper "Equivalence of semi-classical and quantum mechanical descriptions of statistical light beams". In this article we are going to go through some of the basics in developing quantum optics, then land up in E.C.G's original work and try to present it as rigorous as possible. We show some of its important applications in various classes of physics problems.