Hunting dark energy with gravity resonance spectroscopy

Previously, phenomena named 'scalar symmetron fields' have been proposed as a potential candidate for Dark Energy. If they exist, these fields will be far weaker than gravity -- currently the weakest fundamental force known to physics. Therefore, by searching for extremely subtle anomalies in the behaviours of quantum particles trapped in gravitational fields, researchers could prove the existence of these fields experimentally. Within a gravitational field, ultra-cold neutrons can assume several discrete quantum states, which vary depending on the strength of the field. Through GRS, these neutrons are made to transition to higher-energy quantum states by the finely tuned mechanical oscillations of a near-perfect mirror. Any shifts from the expected values for the energy differences between these states could then indicate the influence of Dark Energy.

In their study, Abele's team designed and demonstrated a GRS experiment named 'qBOUNCE,' which they based around a technique named Ramsey spectroscopy. This involved causing neutrons in an ultra-cold beam to transition to higher-energy quantum states -- before scattering away any unwanted states, and picking up the remaining neutrons in a detector. Through precise measurements of the energy differences between particular states, the researchers could place far more stringent bounds on the parameters of scalar symmetron fields. Their technique now paves the way for even more precise searches for Dark Energy in future research.