Quantum Technologies for the Einstein Telescope

Quantum technology is central to the operation of modern gravitational-wave detectors and will play crucial role in the success of next-generation observatories, such as the Einstein Telescope. There, quantum squeezed light will be utilized to suppress quantum noise across the entire detection band, a task that demands advancements in several areas of quantum technology. This review provides an introduction to the quantum technologies employed in gravitational-wave detection and explores in detail their properties, challenges, and the potential they hold for the Einstein Telescope.