Gravity Resonance Spectroscopy Constrains Dark Energy and Dark Matter Scenarios

Abstract

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 Newton's 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 β > 5.8 × 10 8 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axion-like spin-mass coupling is excluded for the coupling strength gsgp > 3.7 × 10 −16 (5.3 × 10 −16 ) at a Yukawa length of λ = 20 µm (95% (C.L.).PACS numbers: 12.15. Ji,13.30.Ce,14.20.Dh,23.40.Bw Experiments that rely on frequency measurements can be performed with incredibly high precision. One example is Rabi spectroscopy, a resonance spectroscopy technique to measure the energy eigenstates of quantum systems. It was originally developed by I. Rabi to measure the magnetic moment of molecules [1]. Today, resonance spectroscopy techniques are applied in various fields of science and medicine including nuclear magnetic resonance, masers, and atomic clocks. These methods have opened up the field of low-energy particle physics with studies of particle properties and their fundamental interactions and symmetries. In an attempt to investigate gravity at short distances, we applied the concept of resonance spectroscopy to quantum states of very slow neutrons in the Earth's gravity potential [2]. Here, we present the first precision measurements of gravitational quantum states with this method that we refer to as gravity resonance spectroscopy (GRS). The strength of GRS is that it does not rely on electromagnetic interactions. The use of neutrons as test particles bypasses the electromagnetic background induced by van der Waals and Casimir forces and other polarizability effects.Within this work, we link these new measurements to dark matter and dark energy searches. Observational cosmology has determined the dark matter and dark energy density parameters to an accuracy of two significant figures [3]. While dark energy explains the accelerated expansion of the universe, dark matter is needed in order to describe the rotation curves of galaxies and the largescale structure of the universe. The true nature of dark energy and the content of dark matter remain a mystery, however. The two most obvious candidates for dark energy are either Einstein's cosmological constant [4] or quintessence theories [5,6], where the dynamic vacuum energy changes over time. The resonant frequencies of our quantum states are intimately related to these models. If some as yet undiscovered dark matter or dark energy particles interact with neutrons, this should result in a measurable energy shift of the observed quantum states. One prom...

Beyond the cosmological standard model

“…As mentioned above, gravitational-strength fifth forces are most strongly constrained by torsion pendulum experiments in the laboratory. In more strongly coupled models, where screening is more powerful, it is possible to use cold neutron systems as a probe: the presence of the chameleon field both alters the energy levels of neutrons bouncing in the Earth's gravitational field [861][862][863] and can alter the phase of neutrons in interferometry [864]. Intermediate between these two regimes, Casimir force experiments cant be used to probe chameleons of moderate coupling [865].…”

T 3-Interferometer for atoms

“…In particular, they experience a potential consisting of the linear ramp and an infinitely steep wall. It is amazing that a measurement of the transitions between the resulting discrete energy levels can put upper bounds [27] on dark energy and dark matter scenarios.…”

Comparison of ultracold neutron sources for fundamental physics measurements

“…in [1,23] or [24,25]), and tests of the weak equivalence principle for the neutron [26][27][28][29] or the theory of neutron diffraction [29,30]. Measurements of gravitationally bound quantum states of neutrons have been used for example for a high sensitivity search of deviations from Newton's gravity law on the sub-millimeter scale [31][32][33].…”