I propose to leverage the unique properties of optical fiber Fabry-Perot (FFP) microcavities pioneered by my group to advance the field of quantum engineering. We will take quantum-enhanced measurement from its current proof-of-principle state to a true metrological level by applying cavity-based spin squeezing to a compact atomic clock, aiming to improve the clock stability beyond one part in 10^-13 in one second. In a new experiment, we will generate multiparticle entangled states with high metrological gain by applying cavity-based entanglement schemes to alkaline earth-like atoms, the atomic species used in today’s most precise atomic clocks. In a second phase, a miniature quantum gas microscope will be added to this experiment, creating a rich new situation at the interface of quantum information, metrology, and cutting-edge quantum gas research. Finally, we will further improve the FFP microcavity technology itself to enable novel atom-light interfaces with a currently unavailable combination of strong coupling, efficient fiber coupling, and open access. This will open new horizons for light-matter interfaces not only in our experiments, but also in our partner groups working with trapped ions, diamond color centers, semiconductor quantum dots, carbon nanotubes and in quantum optomechanics.