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Ancient Greek philosophers used to speculate (as early as 500 BC) on whether matter could be divided at infinitum or whether every material has a smallest part that still shares its properties, the atom (or more generally, the molecule). It took until the late 19-th century to answer this question affirmatively and decisively, mostly via chemistry, statistical mechanics and finally Brownian motion. Feynman was once asked the following question by a reporter: if we wanted to send a single message to extra-terrestrial life, showing the achievements of mankind on earth, what would it be ? His reply was “matter is composed of atoms”.

While a century ago, it was conclusively established that all matter is composed of atoms, it remained an open question as to what atoms themselves looked like, and if they themselves were composites of smaller parts, but whose nature is no longer the same as the atom itself. Of course, we now know that atoms are composed of a nucleus and electrons, and that the nucleus in turn is built from protons and neutrons, themselves built out of quarks and gluons.

Constructing a viable model for the electronic structure of atoms is what originally and primarily drove the development of quantum mechanics. The existence and stability of atoms is a purely quantum mechanical effect. Without the Pauli exclusion principle and the shell structure of electrons, we would loose the chemical and physical properties that distinguish different elements in the Mendeleev table, and there would be no chemistry as we know it. Similarly, the molecular and collective properties of conductors and insulators of heat and electricity have quantum origins, as do the semi-conductors used in building transistors and integrated circuits. Atomic and molecular spectral lines, observed from distant stars and nebulae, have allowed astronomers to conclude that the visible matter in the universe at large is the same as that found on earth. The systematic displacements of these lines inform us on the velocities and the distances of these objects. In summary, quantum physics and quantum phenomena are pervasive in modern science and technology.

Content:-

1. Introduction

2. Two-state quantum systems

3. Mathematical Formalism of Quantum Physics

4. The Principles of Quantum Physics

5. Some Basic Examples of Quantum Systems

6. Quantum Mechanics Systems

7. Charged particle in an electro-magnetic field

8. Theory of Angular Momentum

9. Symmetries in Quantum Physics

10. Bound State Perturbation Theory

11. External Magnetic Field Problems