Bell Inequalities and device-independent quantum information processing




Université libre de Bruxelles (ULB), Belgium

January 25, 2023 12:30 PM

The Nobel Prize in Physics 2022 was awarded jointly to Alain Aspect, John F. Clauser, and Anton Zeilinger "for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science". The violation of Bell inequalities played an important role in the history and foundations of quantum theory, showing that quantum theory was irremediably irreconcilable with classical ways to describe the world. The consequences of this departure from classicality are most manifest in the field of quantum information and computation, where quantum effects are exploited to process and encode information beyond what is possible in the classical world. But now that we are in an age where we fully embrace quantum theory and its weirdest consequences and where experimentalists perform daily quantum experiments much more complex than the early ones by Clauser, Aspect, and Zeilinger, we may ask the question: Are Bell inequalities still relevant today? Do quantum engineers that build quantum information processing devices need to know about them?  I will explain in this talk that yes, the violations of Bell inequalities do not only represent a past milestone in the history of quantum physics, but play a remarkable role in the present and future development of quantum information, enabling certification methods for quantum applications and protocols that do not rely on any characterization of the underlying quantum devices.