PUBLIC LECTURE: From Einstein's photon to Wheeler's delayed choice experiment: illuminating the inner mystery of quantum mechanics

A free public lecture by Alain Aspect, Laboratoire Charles Fabry de l’Institut d’Optique, Palaiseau, France.

Is light a wave or a particle? After many centuries of debate, involving giants such as Newton, Huygens, Young, Fresnel, Maxwell and Einstein, the final answer of quantum mechanics is: “light is both a wave and a particle” at the same time.

Wave-particle duality is at the root of the quantum revolution initiated at the beginning of the 20th century, but explaining the meaning of that weird concept is a difficult challenge. Most textbooks on quantum physics start with a description of an “experiment” to demonstrate it. However, in contrast to common belief, this textbook experiment could not even be conducted until 1985, since it required the development of a source of single photons. An even more fascinating, counter-intuitive and thought-provoking version of that first “thought experiment” – the “delayed-choice experiment” has recently been turned into a real experiment. After addressing the history and the nature of the mystery Professor Aspect will focus on this new experiment, which emphasizes one of the greatest “quantum mysteries” in the words of Richard Feynman.

** Please note that the correct date for this event is Thursday 5 August, not 4 August as was originally advertised**