A Time-Energy Delayed-Choice Interference Experiment for the Undergraduate Laboratory

Laboratory experiments that illustrate the fundamentals of quantum physics are powerful teaching instruments because they re-enact thought experiments, allowing students to think deeper about the quantum-mechanical principles involved. Interference, wave-particle duality and entanglement are among the most important predictions of quantum mechanics. They are abstract and counter-intuitive. More recent concepts that help illustrate these subtleties include quantum erasure and delayed choice. In this article we present an experiment for the undergraduate laboratory that involves all of these issues or concepts. The experiment entails only minor modifications to a well-known setup for doing single-photon interference. In this article we present the experiment, its results and a theoretical description.