We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of the Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate, that Newtons inverse square law of Gravity is understood at micron distances on an energy scale of~$10^{-14}$~eV. At this level of precision we are able to provide constraints on any possible gravity-like interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant~$beta > 5.8times10^8$ at~95% confidence level~(C.L.), and an attractive (repulsive) dark matter axion-like spin-mass coupling is excluded for the coupling strength $g_sg_p > 3.7times10^{-16}$~($5.3times10^{-16}$)~at a Yukawa length of~$lambda = 20$~{textmu}m~(95% (C.L.).
Download