At temperatures close to absolute zero, classical mechanics ceases to be valid and the motion of particles is solely governed by the laws of quantum mechanics, which even allow matter to exhibit a wave-particle duality. To access the ultracold realm tremendous progress has been made in the last three decades and nowadays the field of cold and ultracold atoms is one of the most flourishing in physics. Striking results such as the Bose-Einstein condensation and the superfluid-Mott insulator transition have been achieved, promoting exciting applications particularly in the fields of quantum simulation, quantum computation and sensing. Due to their extraordinary properties, cold atoms systems are also at the core of the emerging quantum technologies, which are attracting huge national and international interest.
This module reviews the key concepts and techniques in modern cold and ultracold atoms physics, and also presents research highlights, with a particular focus on the topics in which the School is active. We will see how laser light can be used to cool and trap atoms and how, with the help of magnetic or dipole traps, it is possible to achieve the lowest temperatures in the Universe, just a few billionths of a degree above absolute zero. We will study the extraordinary properties of quantum gases including Bose-Einstein condensates and Fermi degenerate gases. Finally, we will see how ultracold atoms are being used to develop next-generation technologies.
The topics covered include: basic elements of light-matter interaction; laser cooling and trapping of neutral atoms; magneto-optical trapping; evaporative cooling; quantum degeneracy: the Bose-Einstein condensate and the Fermi gas; superfluidity of Bose-Einstein condensates; optical lattices; quantum technology: atom clocks, atom interferometry, cavity quantum electrodynamics.
Learning Outcomes
By the end of the module students should be able to:
Describe the hyperfine structure of the Hydrogen atom and of the Alkali atoms
Describe effectively the light-matter interaction using the Bloch sphere formalism and be familiar with the concepts of Rabi oscillations and Ramsey sequence
Describe the thermodynamic and the kinetic theory of a gas, and use these to determine the thermodynamic properties of gases in the vicinity of the absolute zero
Describe how laser light is used to cool atomic ensembles, and explain the concepts of Doppler limit and recoil limit
Implement magnetic and dipole traps for neutral atoms and be familiar with the “dressed state” formalism.
Explain how to combine laser cooling and magnetic trapping
Understand the evaporative cooling of trapped atomic gases and the atomic collisions in the ultracold regime
Make, probe and understand quantum degenerate gases: Bose-Einstein condensates and degenerate Fermi gases.
Have detailed knowledge the non-linear Schroedinger equation that effectively describes the superfluid Bose-Einstein condensate and its excitations, from solitons to vortices
Create optical lattices for quantum gases and be familiar with the Bose-Hubbard model
Explain the basic concepts of atom optics and apply them to atom interferometers
Describe the working principles of modern atom clocks and of atoms in optical cavities