This book is an original first approach to quantum physics, the core of modern physics. It combines the competence of a well-known researcher in quantum information science and the freshness in style of two high school students.

Quantum physics is known to be challenging for two reasons: it describes counter-intuitive phenomena and employs rather advanced mathematics. The description of "traditional" quantum phenomena (the structure of atoms and molecules, the properties of solids, the zoology of sub-atomic particles) does indeed involve the whole formalism. However, some other striking phenomena, somehow the most "typically quantum" ones, can be described using only high school mathematical skills. This approach exploits this fact, thus making it possible for a beginner to tackle mind-boggling experiments like teleportation and the violation of Bell's inequalities, and practice notions like superposition, entanglement and decoherence.

This book is an original first approach to quantum physics, the core of modern physics. It combines the competence of a well-known researcher in quantum information science and the freshness in style of two high school students.

Quantum physics is known to be challenging for two reasons: it describes counter-intuitive phenomena and employs rather advanced mathematics. The description of "traditional" quantum phenomena (the structure of atoms and molecules, the properties of solids, the zoology of sub-atomic particles) does indeed involve the whole formalism. However, some other striking phenomena, somehow the most "typically quantum" ones, can be described using only high school mathematical skills. This approach exploits this fact, thus making it possible for a beginner to tackle mind-boggling experiments like teleportation and the violation of Bell's inequalities, and practice notions like superposition, entanglement and decoherence.

Quantum physics is often perceived as a weird and abstract theory, which physicists must use in order to make correct predictions. But many recent experiments have shown that the weirdness of the theory simply mirrors the weirdness of phenomena: it is Nature itself, and not only our description of it, that behaves in an astonishing way. This book selects those, among these typical quantum phenomena, whose rigorous description requires neither the formalism, nor an important background in physics. The first part of the book deals with the phenomenon of single-particle interference, covering the historical questions of wave-particle duality, objective randomness and the boundary between the quantum and the classical world, but also the recent idea of quantum cryptography. The second part introduces the modern theme of entanglement, by presenting two-particle interference phenomena and discussing Bell's inequalities. A concise review of the main interpretations of quantum physics is provided.

Quantum physics is often perceived as a weird and abstract theory, which physicists must use in order to make correct predictions. But many recent experiments have shown that the weirdness of the theory simply mirrors the weirdness of phenomena: it is Nature itself, and not only our description of it, that behaves in an astonishing way. This book selects those, among these typical quantum phenomena, whose rigorous description requires neither the formalism, nor an important background in physics. The first part of the book deals with the phenomenon of single-particle interference, covering the historical questions of wave-particle duality, objective randomness and the boundary between the quantum and the classical world, but also the recent idea of quantum cryptography. The second part introduces the modern theme of entanglement, by presenting two-particle interference phenomena and discussing Bell's inequalities. A concise review of the main interpretations of quantum physics is provided.

The development of quantum technologies has seen a tremendous upsurge in recent years, and the theory of Bell nonlocality has been key in making these technologies possible. Bell nonlocality is one of the most striking discoveries triggered by quantum theory. It states that in some situations, measurements of physical systems do not reveal pre-existing properties; rather, the property is created by the measurement itself. In 1964, John Bell demonstrated that the predictions of quantum theory are incompatible with the assumption that outcomes are predetermined. This phenomenon has been observed beyond any doubt in the last decades. It is an observation that is here to stay, even if quantum theory were to be replaced in the future. Besides having fundamental implications, nonlocality is so specific that it can be used to develop and certify reliable quantum devices. This book is a logical, rather than historical, presentation of nonlocality and its applications. Part 1 opens with a survey of the meaning of Bell nonlocality and its interpretations, then delves into the mathematical formalisation of this phenomenon, and finally into its manifestations in quantum theory. Part 2 is devoted to the possibility of using the evidence of nonlocality for certification of devices for quantum technologies. Part 3 explores some of the extensions and consequences of nonlocality for the foundations of physics.