Like the first book in this series, this book falls into the neglected space between the typical popular science book, which is often fluffy and rather unsatisfactory, and the serious text book, which is usually too involved for a layman.<br><br>Apart from the usual discussion of spin, Schroedinger’s equation etc., this book puts a lot of emphasis on entanglement and the related measurement problem. The use of density matrices to analyze parts of a (possibly entangled) system is explained. The book also includes a short introduction to the path-integral method, unfortunately without discussing how the classical path emerges from the superposition. Finally, the quantum harmonic oscillator and the use of raising/lowering operators is explained.<br><br>Overall: a pleasure to read, very well done!