Quantum Phenomena and the Double-Slit Experiment
The aim of this chapter is to introduce, in concrete physical terms, quantum phenomena, by which I, again, mean those physical phenomena in considering which Planck’s constant h cannot be neglected. I shall do so by way of the double-slit experiment, a paradigmatic or, it is sometimes argued, even the paradigmatic quantum experiment, in which the famously strange features of quantum phenomena manifest themselves. This experiment and the way it reflects such key features of quantum phenomena as the uncertainty relations and the probabilistic nature of our quantum predictions are considered in Sections 2.1 and 2.2. Sections 2.3 and 2.4 discuss two other experiments that are closely related to the double-slit experiment: the delayed-choice experiment, due to John A. Wheeler, and the quantum eraser experiment, due to Marlan Scully and his coworkers. Section 2.5 uses the quantum eraser experiment to establish the fundamental difference between classical and quantum physics by considering the repetition of the identically prepared experiments in each domain.