Quantum phenomena in gravitational field

The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold antihydrogen above a material surface and measuring a gravitational interaction of antihydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eِtvِs-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology.