Tobias Jenke of Vienna and 11 co-authors from Austria, Germany, and France have performed an interesting experiment with neutrons in the gravitational field (although they have done similar experiments in the past) and their new preprint was just published in the prestigious PRL (Physical Review Letters):
Gravity Resonance Spectroscopy Constrains Dark Energy and Dark Matter Scenarios (arXiv, PRL)Recall that neutrons' wave functions in the Earth's gravitational field have previously been mentioned on this blog as a way to debunk the "gravity as an entropic force": LM, Archil Kobakhidze.
Semi-popular: APS, ArsTechnica, Huff. Post
Click to zoom in: outline and results.
What have they done?