ABSTRACT
CONTENTS 2.1 Single Photons and Beam Splitters ............................................................ 12 2.2 Brown-Twiss Interferometer ...................................................................... 15 2.3 Mach-Zehnder Interferometer .................................................................. 17 2.4 Detection of Photon Pulses ......................................................................... 19 2.5 So What Is a Photon? ................................................................................... 21 Acknowledgment .................................................................................................. 21 References .............................................................................................................. 21
The concept of the photon is introduced by discussion of the process of electromagnetic field quantization within a closed cavity or in an open optical system. The nature of a single-photon state is clarified by consideration of its behavior at an optical beam splitter. The importance of linear superposition or entangled states in the distinctions between quantum-mechanical photon states and classical excitations of the electromagnetic field is emphasized. These concepts and the ideas of wave-particle duality are illustrated by discussions of the effects of single-photon inputs to Brown-Twiss and Mach-Zehnder interferometers. Both the theoretical predictions and the confirming experimental observations are covered. The defining property of the single photon in terms of its ability to trigger one, and only one, photodetection event is discussed.
