We promise, physicist Alain Aspect will grow back his famous mustache for the Nobel Prize in Stockholm on December 10, as he said during the “Quotidien” program on TMC on October 5. The attribute that has distinguished him since his youth has indeed given way to a graying beard for a few weeks.
For the rest, at 75, he does not change. Accent from the South-West, sparkling eye when he explains with many gestures the behavior of his favorite objects, photons, grains of light… And an incredible memory of the smallest details of the experiences that made him famous and earned him the reward this year alongside American John Clauser and Austrian Anton Zeilinger. All three, at different times – the 1970s, 1980s and 2000s – settled an almost philosophical debate on the interpretation of quantum mechanics, which had been stirring the brightest minds, including Albert Einstein and Niels Bohr, for fifty years.
Is quantum mechanics, developed in the inter-war period to explain the behavior of electrons, atoms or photons (in short everything around us!), intrinsically weird or “normal”, seeming strange only because his description is incomplete, as if a magician’s trick remained to be discovered?
“No one believed it”
“The beast resists! It’s strange but that’s the way it is”, slice Alain Aspect, fifteenth French Nobel in physics, in his office at the Optical Institute (in Palaiseau, in Essonne), with shelves crumbling under the theses of his masters, colleagues or students. The “beast” is quantum mechanics, of which he observed an astonishing property, which proves Bohr right against Einstein. If you make, with a little subtlety, two photons per pair and move them far apart, their properties will remain linked, even at great distances. Touching one will instantly modify the other with a 100% sure result. It’s quantum entanglement.
“When we tackled this question, in the lab nobody believed it and some laughed”remembers Philippe Grangier, doing a thesis in 1981 with Alain Aspect, during the first experiments at the Institute of Optics at the University of Paris-Saclay.
To fight against adversity, Alain Aspect deployed several of his qualities. Resourceful, he invented his own components, which did not exist anywhere else, as a source of photons much better than that of the pioneer John Clauser. He had electronic equipment lent by a CEA laboratory near the Optics Institute, his « maison »whom he constantly thanks for his support.
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