Concepts for long-baseline high-mass matter-wave interferometry This special issue is honoring the 60th birthday of Wolfgang Schleich. Our contribution relates closely to his seminal research and teaching on quantum physics in phase space

Designing experiments which delocalize ever more complex and more massive particles requires a quantitative assessment of new interferometer configurations. Here, we introduce a figure of merit which quantifies the difference between a genuine quantum interference pattern and a classical shadow and use it to compare a number of near-field interferometer schemes. This allows us to identify the most promising setups for future tests of the quantum superposition principle, and to discuss the perspectives of interferometry with complex molecules and clusters.