The Quantum Divide Why Schrödinger's Cat is Either Dead or Alive

Using a selection of key experiments performed over the past 30 years or so, we present a discussion of the strikingly counter-intuitive phenomena of the quantum world that defy explanation in terms of everyday "common sense" reasoning, and we provide the corresponding quantum mechanical explanations with a very elementary use of associated formalism. Most, but certainly not all, of the experiments we describe are optical experiments involving a very small number of photons (particles of light). We begin with experiments on the wave-particle duality of electrons, proceed to experiments on the particle nature of light and single photon interference, delayed choice experiments and interaction-free detection, then go on to experiments involving the interference of two photons, quantum entanglement and Bell's Theorem, quantum teleportation, large-scale quantum effects and the divide between the classical and quantum worlds, addressing the question as to whether or not there is such a divide.

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.