The course combines concepts of Quantum Optics and Coherent X-ray Optics. The study of the interaction of optical light with resonant electronic transitions in atoms has led to the development of many high-impact quantum-based devices, such as lasers, atomic clocks or miniature sensing, and in parallel to new quantum technologies such as quantum cryptography and computing. However, in the near future, harnessing the interaction between atoms and hard x-ray photons with a far larger energy than optical photons may be advantageous. X-ray photons are much easier to detect, can penetrate deeper into materials, can be focused to much smaller spot sizes, and should in principle support faster information processing. Ongoing efforts in the understanding and exploiting quantum dynamics with x-rays are supported by the recent commissioning of novel high-frequency light sources that render x-ray quantum optics possible. The lecture will follow the recent progress made in this direction introducing the related theoretical concepts of quantum optics, atomic physics, and light-matter interaction, together with an overview of present applications such as imaging at the x-ray free electron laser.