December 2-4, 2009
published July 05, 2010
Almost 50 years ago, Robert Hanbury Brown installed the Narrabri Stellar Intensity Interferometer. With the help of Richard Q. Twiss, they mathematically explained the working principle of this instrument and their successful measurements of stellar radii by correlating fluctuations of light intensities, instead of fringes produced by interferences of electrical fields. With this experiment, they opened up the use of second-order correlation functions, and somehow participated in the development of what is called today "quantum optics". The "HBT effect" still represents a key element of quantum optics textbooks. In 2005, Prof. Roy Glauber received the Physics Nobel Prize for his work on quantum coherence. However, the HBT effect has long ago disappeared from astrophysics which is so far only making use of the various forms of the first-order correlation function: spectra, images, visibilities.
Our aim is to reopen the question of higher-order coherence and quantum phenomena in astrophysics, and to go beyond with the help of Extremely Large Telescopes and ultimate photon-counting devices. As matter of fact, stellar radii, and more generally stellar imaging, can be achieved using intensity interferometers, but under the fundamental condition that the source is essentially thermal. On the other hand, full second-order correlation function and quantum coherence, observed on thermal or non-thermal cosmic sources represent an unknown field, while many fascinating results and phenomena have already been demonstrated: slow light, entanglement, squeezed states, vorticity...
The workshop "Quantum of Quasars" aims to bring together astrophysicists, quantum optics physicists and engineers working on ultra-fast light detection to explore how quantum optics and astrophysics could be (re)connected to achieve a better understanding of cosmic objects and light itself.