### From Bell's inequality to quantum computers: the long journey of Alice and Bob

It will be 55 years in a few months, since the fundamental paper by John Bell ("On the Einstein Podolsky Rosen Paradox", Physics. 1: 195?200) was published. It is fair to say that the consequences of that extraordinary work went way beyond imagination, revolutionizing our understanding of nature, and providing the necessary momentum for moving towards a world where "quantum" is the common adjective for communication and computation, for logics and biology, for teleportation and the internet. In this seminar we will first meet the players of the quantum world (qubits, quantum gates, and measuring apparatuses), and see how they appear from the backstage of quantum mechanics. We will then introduce the true lead of the scene, namely "entanglement", and show why and how it really makes the difference between quantum and classical. The second part of the seminar will see us following the journey that took the most famous qubit-pair, Alice and Bob, from the quantum parallelism of the Deutsch algorithm and the incredible speed-up of the quantum Fourier transform, to the experiment that realized quantum teleportation through the 143km between Las Palmas and Tenerife and the quantum computers which are today up and running in several laboratories. We will finally end our excursion with a view into the future of quantum biology and quantum learning machine.

**Friday, 22 March 2019, ore 14:30 — Aula Magna "Tullio Regge" **