‎'‎A masterful and beautifully written exposition of the theoretical ideas and tools of quantum optics that every serious student or researcher‎,‎ theorist or experimentalist‎,‎ should have under their belt‎.‎ Leonhardt tells a connected story‎,‎ while making each discussion as ‎'‎simple as possible‎,‎ but not simpler‎'‎‎.‎‎'‎ Michael G‎.‎ Raymer‎,‎ University of Oregon ‎'‎I used Ulf Leonhardt‎'‎s ‎'‎Measuring the Quantum State of Light‎'‎ ‎(‎MQSL‎)‎ in my quantum optics course when the book first appeared in 1997‎,‎ and wished it were longer‎.‎ Leonhardt writes in a lucid prose that moves quickly from basics to deep applications in clever‎,‎ efficient derivations that are accessible to advanced undergraduates‎.‎ Essential Quantum Optics expands the earlier work and breaks new pedagogical ground with a ‎'‎Horizons‎'‎ chapter on the intersection of optics and general relativity‎.‎ Topics like Unruh and Hawking radiation are beautifully explained and related to concepts more familiar to the optics and atomic physics community‎.‎ Leonhardt and collea‎.‎‎.‎‎.‎