## Atomic Physics (Part III Major Option)

Michaelmas Term

Zoran Hadzibabic

The ability to control and cool atoms by laser light has given a completely new twist to the traditional field of atomic physics in recent years. The Nobel prizes in physics of 1997, 2001, and 2005 document the fascinating recent advances in this field. Macroscopic quantum phenomena such as Bose-Einstein condensation and superfluidity have become experimentally accessible and the fundamental laws of quantum mechanics have been studied with unsurpassed precision. This lecture will serve as an introduction to this exciting field and give insight into the current state of research. It is intended to convey a basic understanding for the current research in the wider range of atoms, lasers, and quantum gases. Emphasis will be put on the connection between theory and experimental observation.

**Contents:**

**Introduction and revision of basic concepts:**Bohr’s theory, Einstein A&B coefficients, Stern-Gerlach experiment.**Atomic structure:**Hydrogen atom, fine structure, Lamb shift, hyperfine structure, electric dipole transitions, selection rules, Zeeman effect, magnetic dipole transitions, alkali atoms.**Fundamentals of atom-laser interaction:**Driven two-level system, Ramsey spectroscopy and atomic clocks, density matrix, optical Bloch equations, dissipation, cross-sections & line shapes, Doppler-free laser spectroscopy, ac Stark effect, two-photon and Raman transitions.**Laser cooling & trapping:**Scattering force, slowing of atomic beams, optical molasses, Doppler cooling limit, magneto-optical trap, optical dipole trap, Sisyphus cooling below the Doppler limit.**Evaporative cooling and Bose-Einstein condensation of atomic gases:**Requirements, magnetic trapping, evaporative cooling, critical temperature, condensate fraction, experimental observation of Bose-Einstein condensation.**Properties of atomic Bose-Einstein condensates:**Atomic interactions, macroscopic wavefunction, matter-wave interference of Bose-Einstein condensates, Gross-Pitaevskii equation, Thomas-Fermi approximation, Bogoliubov excitation spectrum, superfluidity.

**Suggested Reading:**

- C. Foot, Atomic Physics, Oxford University Press, 2004.

- C. J. Pethick and H. Smith, Bose-Einstein condensation in dilute gases, Cambridge University Press, 2002.

For further information, please contact Zoran Hadzibabic