The effects of gravity and quantum mechanics can be probed simultaneously using spectroscopy, reports a paper online this week in Nature Physics. This method might lead to sensitive tests of gravity laws.
Spectroscopic techniques are typically applied to study the interaction between matter and electromagnetic fields. In contrast, Hartmut Abele and colleagues use such techniques to probe the quantum effects of gravity. They bounce neutrons off a mechanically vibrating mirror, and use this to probe transitions between quantum states of neutrons in the Earth\'s gravitational field. Similar experiments have been done before, but this is the first to use spectroscopy to sensitively measure the properties of these bouncing neutrons.