Sommaire:

Exceptionnally the colloquium is opened to all students of the Physics Department. Detecting gravitational waves required 4 decades of experimental effort to reach a sensitivity at the h~10-21 level, corresponding to mirror displacements below 10-18 m. I will review this "noise hunting" effort and give some details about the recent observation of 2 black hole mergers. Apart from classical noise (seismic noise, thermal noise...), it was realized as soon as in the late 70s that quantum fluctuations of the light field were responsible for the Standard Quantum Limit, a sensitivity limit that second-generation gravitational-wave interferometers will reach once they operate at their design sensitivity. A number of ideas have been considered to beat the SQL: squeezed states of the light field, tailoring the optical response function or taking advantage of the mirror mechanical response to radiation pressure. I will present the first experimental demonstrations of such ideas, either on suspended interferometers or table-top experiments. I will also discuss how recent progress in micro/nanomechanics has allowed the emergence of the new field of quantum optomechanics, which addresses the quantum aspects of both the light field and the mechanical resonator. This new field is very promising both for the study of the foundations og quantum mechanics (quantum states and decoherence of macroscopic objects...) and for quantum information. I will present a few typical recent experiments.

Pour plus d'informations, merci de contacter Rousseau E.