  These are the lecture notes for a course that I am teaching at Zhiyuan
College of Shanghai Jiao Tong University (available at
https://www.youtube.com/derekkorg), though the first draft was created for a
previous course I taught at the University of Erlangen-Nuremberg in Germany. It
has been designed for students who have only had basic training on quantum
mechanics, and hence, the course is suited for people at all levels. The notes
are a work in progress, meaning that some proofs and many figures are still
missing. However, I've tried my best to write everything in such a way that a
reader can follow naturally all arguments and derivations even with these
missing bits. Quantum optics treats the interaction between light and matter.
We may think of light as the optical part of the electromagnetic spectrum, and
matter as atoms. However, modern quantum optics covers a wild variety of
systems, including superconducting circuits, confined electrons, excitons in
semiconductors, defects in solid state, or the center-of-mass motion of micro-,
meso-, and macroscopic systems. Moreover, quantum optics is at the heart of the
field of quantum information. The ideas and experiments developed in quantum
optics have also allowed us to take a fresh look at many-body problems and even
high-energy physics. In addition, quantum optics holds the promise of testing
foundational problems in quantum mechanics as well as physics beyond the
standard model in table-sized experiments. Quantum optics is therefore a topic
that no future researcher in quantum physics should miss.
