Atomic physics

A.Y. 2021/2022
Overall hours
Learning objectives
The course intends to introduce the students to the basic principles of the resonant interaction between atoms and electromagnetic radiation. Starting from the semiclassical description of a two-level atom interacting with a monochromatic and quasi-resonant radiation field, they will be able to understand the laser and the different regimes of stimulated, spontaneous and superradiant emission. They will be introduced to the modern techniques of laser cooling and trapping, to the Bose-Einstein condensation and to several collective effects, as the collective atomic recoil laser and the free electron laser.
Expected learning outcomes
The student at the term of the course will have learned the following topics:
A) description of absorption, spontaneous, stimulated and superradiant emission.
B) principles of the laser operation
C) main quantum effects in the emission and absorption of photons by a two-level atom
D) basic principles of a magneto-optical trap (MOT) and a dipole trap, with some overview on more advanced techniques, e.g. the Sisyphus effect.
E) basic principles of Bose-Einstein condensation in harmonic traps
F) collective effects, as the collective atomic recoil laser and the free electron laser
Course syllabus and organization

Single session

Lesson period
First semester
More specific informations on the delivery modes of training activities for the academic year 2021/2022 will be provided over the coming months, based on the evolution of the public health situation.
Course syllabus
1. Theory of the interaction between radiation and matter:

a. Semi-classical resonant interaction atom-radiation theory: coefficient; Rabi solution; Optical Bloch (OB) equations; Vectorial description. Einstein A and B coefficients. Perturbative solution and evaluation of the B coefficient.
Relaxation terms in the OB equations. Maxwell-Bloch equations. Stationary solution and atomic saturation; non-homogeneous broadening. Photon eco and saturation spectroscopy.

b. From the semi-classical theory to quantum theory of radiation: E.m. field quantization and atom-radiation interaction Hamiltonian. Number states and coherent states of radiation. Quantum Rabi oscillations (Jaynes-Cumming solution). Weisskopf-Wigner theory of spontaneous emission. Light fluorescence spectrum, elastic and inelastic spectrum (triplet Mollow).

c. Optical cavity and lasers: Cavity equation and modes. MB equations with a ring cavity (mean field model). Rate equations. Single-mode lasers and Ginzburg-Landau equation. Multi-mode lasers.

d. Transient cooperative phenomena: atomic superradiance.

2. Mechanical effect of radiation: radiation force on two-level atoms. Scattering force. Optical melassa, optical cooling and Doppler limit. Magneto-optical trap (MOT). Dipole force. Sisyphus cooling. Optical gratings.

3. Bose-Einsten Condensates: Brief history of BE condensation and production of BEC with atoms in harmonic traps. Elements of quantum statistics. BE condensation in 3D harmonic traps and in a box. Atom-atom interaction and Gross-Pitaevskii equation. Thomas-Fermi distribution. Feschbach resonances.

4. Bragg diffraction of ultracold atoms. Optical lattice and Bose-Hubbard Hamiltonian. Mott insulator- superfluid phase transition.

5. Collective Atomic Recoil Laser (CARL): Classical and quantum models.

6. Free Electron Laser (FEL): From synchrotron light to FEL. High-gain and x-ray FELs. Analogies between CARL and FEL.
Prerequisites for admission
No prior knowledges are required
Teaching methods
Lectures in presence or, if required, in remote, synchronized and recordered
Teaching Resources
C. J. Foot, "Atomic Physics", Oxford Univ. Press.
M. O. Scully & M. S. Zubairy, "Quantum Optics", Cambridge Univ. Press.
M. Inguscio and L. Fallani, "Atomic Physics", Oxford Univ. Press.
Notes available on the web platform Ariel.
Assessment methods and Criteria
Oral colloquium about the topics of the course program. Verify that the candidate has reached the main learning objectives of the course and his ability to describe the main phenomena presented in the lectures.
FIS/03 - PHYSICS OF MATTER - University credits: 6
Lessons: 42 hours
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