Physics Department Colloquia
Thirty years later, John Stuart Bell discovered that it is possible to settle the debate experimentally, by testing the famous "Bell's inequalities", and to show directly that the revolutionary concept of entanglement is indeed a reality. A long series of experiments closer and closer to the ideal scheme proposed by Bell has confirmed that entanglement is indeed "a great quantum mystery", to use the words of Feynman.
Based on that concept, a new field of research has emerged, quantum information, where one uses quantum bits, the so-called “qubits”, to encode the information and process it. Entanglement between qubits enables conceptually new methods for processing and transmitting information. Large-scale practical implementation of such concepts might revolutionize 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. To cite only the simplest example of these new concepts, quantum cryptography allows one to guarantee an absolute privacy of communications, based on the most fundamental laws of quantum mechanics.