Refined ultralight scalar dark matter searches with compact atom gradiometers

Abstract

Atom interferometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultra-light scalar dark matter (ULDM). Previous studies have focused on the sensitivity to ULDM of km-length atom gradiometers, where atom interferometers are located at the ends of very-long baselines. In this work, we generalise the treatment of the time-dependent signal induced by a linearly-coupled scalar ULDM candidate for vertical atom gradiometers of any length and find correction factors that especially impact the ULDM signal in short-baseline gradiometer configurations. Using these results, we refine the sensitivity estimates for AION-10, a compact 10 m gradiometer that will be operated in Oxford, and discuss optimal experimental parameters that enhance the sensitivity to linearly-coupled scalar ULDM. After comparing the sensitivity reach of devices operating in broadband and resonant modes, we show that welldesigned compact atom gradiometers are able to explore regions of dark matter parameter space that are not yet constrained.

Light propagation and atom interferometry in gravity and dilaton fields

“…However, the dilaton indeed contributes to the phase of an atom interferometer [16][17][18][19][20][21][22][23][24] because the complete Hamiltonian for a particle of mass 𝑚 and momentum p is…”

“…The Hamiltonian also includes time-dependent modifications caused by the dilaton field that are independent of gravity, which can be connected to dark matter [15][16][17][18]22]. Here, we anticipated that an atom interferometer consists of at least two branches by introducing the superscript 𝜎 = 𝑢, 𝑙 for the upper and lower branch.…”

“…They can be motivated by String Theory [13] and influence the propagation of light and matter, leading to deviations from established laws of physics. While effects on matter have been thoroughly discussed [4,[14][15][16][17][18][19][20][21][22][23][24], we focus on the electromagnetic field interacting with the dilaton and study the detection of dilaton fields by light-pulse atom interferometers [25,26].…”

“…Since the internal atomic structure depends on the value of these constants, atomic clocks [44][45][46][47][48][49] can be used to search for EPP violations [4,14] and dark matter [15,50,51]. Similarly, in light-pulse atom interferometers [25,26,52] matter propagates within dilaton fields and consequently such devices are susceptible [53] to both EPP violations [19-21, 23, 54] and dark matter [16][17][18]22]. However, with light pulses being an essential tool to manipulate the atoms, their modified behavior in gravity [55][56][57][58][59][60][61] and dilaton fields has to be taken into account for a consistent description of such experiments.…”

“…To showcase the combined influence of light propagation and dilaton on atom interferometers, we * fabio.di-pumpo@uni-ulm.de; fabio.di-pumpo@gmx.de study different schemes including gradiometers, EEP tests, and dark-matter detectors. For the latter, we consider the spatial dependence of the dilaton field and discuss its consequences, which was not taken into account in previous treatments [16][17][18]22].…”