Hanburry Brown and Twiss, Hong Ou and Mandel effects and other landmarks in Quantum Optics: from photons to atoms

In this lecture, I first present my views on the second vs the first quantum revolution, then describe the Hanbury Brown and Twiss effect with photons, and indicate why it was so important in the development of modern quantum optics. The presentation of our experiments on the HBT effect with atoms will allow me to emphasize the analogies but also the increased richness of the effect when going from photons to atoms. I will similarly describe the HOM effect for photons and its significance, and then present the analogous experiment with atoms. In conclusion, I will put these two effects in the long list of landmarks in the development of quantum optics, and indicate what has been done and what remains to be done with atoms in lieu of photons.