Lecture summary: In 1935, with co-authors Podolsky and Rosen, Einstein discovered an amazing quantum situation, where particles in a pair are so strongly correlated that Schrödinger called them “entangled”. By analysing that situation, Einstein concluded that the quantum formalism was incomplete. Niels Bohr immediately opposed that conclusion, and the debate lasted until the death of these two giants of physics, in the 1950’s.

In 1964, John Bell produced his famous inequalities, which allowed experimentalists to settle the debate, and to show that the revolutionary concept of entanglement is indeed a reality.

Based on that concept, a new field of research has emerged, quantum information, where one uses quantum bits, the so-called “qubits”. In contrast to classical bits which are either in state 0 or state 1, qubits can be simultaneously in state 0 and state 1, as a Schrödinger cat could be simultaneously dead and alive.

Entanglement between qubits enables conceptually new methods for processing and transmitting information. Large scale practical implementation of such concepts might revolutionise our society, as did the laser, the transistor and integrated circuits, some of the most striking fruits of the first quantum revolution, which began with the 20th century.

Speaker biography: Professor Alain Aspect is a distinguished CNRS scientist and professor at the  Institut d’Optique in Palaiseau, France. Born in 1947, he studied at the Ecole Normale Supérieure de Cachan and Université d’Orsay. His ‘Experimental Tests of Bell’s Inequalities with Correlated Photons’, with Jean Dalibard and Philippe Grangier, were the subject of his doctorate (1983). He then developed, with Philippe Grangier, the first source of single photons, used in experiments on wave-particle duality.

From 1985 to 1992 he worked with Claude Cohen-Tannoudji at the Laboratoire Kastler Brossel de l’ENS and Collège de France, on cooling atoms with lasers, in particular cooling below the ‘one photon recoil’.

Since 1991, he has been Head of the Group of Atom Optics which he established at the Institut d’Optique, Palaiseau. Recent scientific projects have included work on Bose-Einstein condensates and atom lasers, quantum atom optics, and quantum simulators with ultra cold atoms. Alain Aspect holds the position of CNRS Distinguished Scientist and Professor at Institut d’Optique and Ecole Polytechnique, Palaiseau.

He is member of academies in France, USA and Austria. In the recent years, he has been awarded the CNRS Gold Medal (2005), the EPS Quantum Optics Senior Prize (2009) and the Wolf Prize in Physics (2010).

This event is free of charge and is followed by a drinks reception.

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