The word quantum is a Latin word that means “how much” in modern understanding, the quantum means the smallest possible discrete unit of any physical property, such as energy or matter. The “Quantum” word was first introduced by Max Planck and Niels Bohr, who are the inventors of quantum theory. For this work, they received a Nobel prize in physics. After them, Einstein also described the quantum theory in his theory of photoelectric effect, where the light was considered quanta, and in 1921, he also won a Nobel prize for his great work.