ImPhys colloquium | William Guerrin

"Revival of intensity interferometry with modern photonic technologies"

The discovery of the "Hanbury Brown and Twiss effect" in the 1950s has been a key in the birth of modern quantum optics.

But Hanbury Brown and Twiss were astronomers! What they actually did is to develop a new technique, called intensity interferometry, which consists in inferring the diameter of a star by measuring the spatial intensity correlation function with two separated telescopes.  After impressive success in the 1960s-1970s, this technique was abandoned because of its poor sensitivity, in particular compared to direct (“amplitude”) interferometry. However, intensity interferometry presents the important advantage of being much easier to implement. This fact, as well as the progress achieved in photon detectors and associated digital electronics, have sparked a renewed interest in intensity interferometry involving many research groups worldwide.

After a general introduction on the physics and history of intensity interferometry, I will present a short overview of the current effort in the community to revive this technique. I will then present our approach in Nice, which is to implement intensity interferometry on existing optical telescopes using single-photon detectors. I will also briefly discuss our next challenges.