Focus on modern frontiers of matter wave optics and interferometry

Intro:

Louis de Broglie’s concept of matter waves is indisputably one of the cornerstones that paved the way for the development of modern quantum physics; the first interference experiments with electrons, neutrons and other light-weight particles confirmed the existence of matter waves very soon after the initial proposal by de Broglie in 1923. It took, however, several decades before the idea could also be routinely applied to more complex particles, such as alkali atoms or molecules. The scientific and technological advances of the last decade have yielded spectacular achievements in the area of matter wave optics. Today, it is a multifaceted, interdisciplinary field that enables scientists to coherently manipulate objects from electrons and neutrons over quantum degenerate atomic ensembles up to large molecules and complex clusters. The level of experimental control and the detailed theoretical understanding of matter wave physics have led to a renaissance of experiments testing the very foundations of quantum mechanics and general relativity, as well as to applications in metrology. A variety of interferometric quantum sensors surpasses or will surpass the limits of their classical counterparts, for instance in the measurement of frequency and time or forces such as accelerations due to rotation and gravity with applications in basic science, navigation and the search for natural resources. The collection of original articles published in this focus issue is intended as a snapshot of the current research pursued by a number of leading teams working on the development of new matter wave physics, devices and techniques. A number of contributions also stress the close relation between the historic roots of quantum mechanics and aspects of modern quantum information science which are relevant for matter wave physics. In what follows, we briefly summarize the content of the contributions.