A semi-popular account of quantum physics based primarily on optical experiments performed over the past three decades. The book discusses how and where one can draw the border between the quantum and classical worlds, or indeed whether a border needs to be drawn at all.

1. Physics Fundamentalism ; 2. The Duality of Particles and Waves: The Split Personality of Electrons ; 3. The Duality of Particles and Waves: Photons ; 4. More Fun With Photons: Photon Splitting and its Uses ; 5. Entanglement and Non-Locality: Spooky Actions at a Distance ; 6. Quantum Information, Quantum Cryptography, and Quantum Teleportation ; 7. Schrodinger's Cat and Leggett's SQUID: Quantum Effects on a Large Scale? ; 8. Quantum Philosophy ; Appendix A: A Quantum Mechanics Timeline ; Appendix B: Quantum Mechanics Experiments for Undergraduates

`... the agreeable style and exceptional clarity of the writing makes this book a great pleasure to read ... the value of the book is above all in its comprehensible accounts of some very important and subtle experimental work, accompanied by excellent diagrammatic illustrations of the relevant apparatus. I have not encountered a better exposition of these, and can heartily recommend the book on this basis. ' Peter J. Bussey, Contemporary Physics `An instructive and entertaining read - an excellent example of what 'popular science for scientists' should be. [...] It gives a balanced and up-to-date account of fascinating quantum phenomena well beyond the double-slit experiment and Schrödinger's cat paradox. It also advocates a more relaxed approach. Quantum mechanics is weird, but not that weird. ' Nature Physics `The burgeoning fields of quantum computing, information processing and simulation develop rapidly as a consequence of theoretical insight and technological developments. The latter have enabled us to take single atoms or ions and count single photons, and many of the thought experiments discussed in earlier treatments of quantum physics have now been conducted in laboratories. This lucid account by Gerry and Bruno presents a mature discussion of the link between the microscopic quantum and the macroscopic classical worlds and will be useful for professional physicists, students and the educated layman. ' Ifan Hughes, Durham University `Gerry and Bruno succeed in introducing the quantum world in a readable but not oversimplified way. Their engaging and original account will particularly satisfy those who find popular texts on quantum mechanics lacking in technical detail. The Quantum Divide will leave readers understanding Feynman's quote with its original intent - not as an admission of defeat but as an invitation to the fascinating world of quantum physics. ' Dan Browne, Science `Highly recommended. ' M. Dickinson, CHOICE `To understand quantum information is to understand the mathematics describing it; without the mathematics you can have only the haziest picture of what the field is all about. In The Quantum Divide, Christopher Gerry, a theoretical physicist, and Kimberley Bruno, a school teacher and vice principal, have done an impressive job in cutting the necessary mathematics down to the absolute minimum, below what I previously thought was possible... An unusual feature of The Quantum Divide is that the authors do not content themselves with theory but always describe relatively simple experiments that demonstrate the expected behaviour. ' Jonathan Jones, Physics World

Develops an easy understanding of quantum mechanics based on modern experiments performed over the past 30 years Discusses why the Schrödinger state of a cat being simultaneously alive and dead can never be seen in the everyday world Shows how quantum mechanics provides a consistent explanation of phenomena while an everyday, classical, picture of the world does not Describes landmark experiments on single photons and electrons made possible by recent technological advances Discusses quantum entanglement, quantum information processing, and quantum teleportation Discusses the connection between quantum entanglement and quantum non-locality through the Hardy-Jordan version of Bell's Theorem Discusses the observation of quantum behavior in large-scale quantum systems where one might otherwise expect only classical-like behavior Discusses the issue of the quantum/classical divide, following the modern viewpoint that there is no quantum divide at all

Christopher Gerry is Professor of Physics at Lehman College, The City University of New York, where his areas of research include theoretical quantum optics, quantum information theory, quantum metrology and sensing, and group theoretical methods in quantum optics and quantum theory in general. Kimberley Bruno is Vice Principal of Williamsburg High School for Architecture and Design, Brooklyn, New York.

Develops an easy understanding of quantum mechanics based on modern experiments performed over the past 30 years Discusses why the Schrödinger state of a cat being simultaneously alive and dead can never be seen in the everyday world Shows how quantum mechanics provides a consistent explanation of phenomena while an everyday, classical, picture of the world does not Describes landmark experiments on single photons and electrons made possible by recent technological advances Discusses quantum entanglement, quantum information processing, and quantum teleportation Discusses the connection between quantum entanglement and quantum non-locality through the Hardy-Jordan version of Bell's Theorem Discusses the observation of quantum behavior in large-scale quantum systems where one might otherwise expect only classical-like behavior Discusses the issue of the quantum/classical divide, following the modern viewpoint that there is no quantum divide at all