Physics Colloquium

Abstract: The 2022 Nobel Prize in Physics 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 inequality derived by Bell in 1964 and later by Clauser, Horne, Shimony, and Holt provided a setup potentially testable experimentally on the issue whether quantum mechanics or classical local realistic theory is the correct theory, which was raised in a paper by Einstein, Poldoskly and Rosen in 1935, "Can Quantum Mechanical Description of Physical Reality Be Considered Complete?" The experiments by Clauser, later by Aspect and more extensively by Zeilinger demonstrated the violation of the inequalities and supported that quantum mechanical entanglement is a physical phenomenon that cannot be explained by classical theory. These pioneering experiments on quantum entanglement stimulated the emergence of a new and interdisiciplinary field, which, by now, is known as quantum information science. The theorteical, experimental and technological development has come a long way and, unimaginable decades ago, there now exist controllable quantum systems over one hundred quantum bits available and this opens up possibilities of using quantum computers to solve difficult problems and advance science and technology. In this talk, I will first describe the story behind the Bell inequalities and then give a bird's-eye view of selected developments in quantum information. If time permits, I will describe some of my own research results, including the use of noisy intermediate-scale of quantum computers.