Cool Physics #1: the quantum states of Earth's gravitational field

Off-the-cuff overview of a set of physics experiments that measured the quantum states of Earth's gravitational field using a beam of neutrons.

Some relevant references:

https://www.nature.com/articles/415297a/

https://arxiv.org/abs/hep-ph/0301145

https://arxiv.org/pdf/0808.1362.pdf