A Nuclear Interferometer for Ultra-Light Dark Matter Detection

Abstract

We propose the nuclear interferometer - a single-photon interferometry experiment based upon the thorium-229 nuclear clock transition - as a novel detector for ultra-light dark matter. Thanks to the enhanced sensitivity of this transition to the variation of fundamental constants, we find that possible realisations of such an experiment deploying either single ions or clouds of atoms have the potential to complement advanced very-long-baseline terrestrial clock atom interferometers in the search for ultra-light dark matter with scalar couplings to photons in the future. Nuclear interferometry may also offer an unparalleled window to new physics coupling to the QCD sector via quarks or gluons, with a discovery reach that could enhance existing and proposed experiments over a range of frequencies in the direction of well-motivated parameter space.

Figures (9)

• Figure 1: A schematic spacetime diagram of a vertical single-photon atom gradiometer with $n = 4$ large-momentum-transfer atom optics. The experiment comprises a pair of single-photon atom interferometers based on single-photon transitions between a ground (blue) and excited (red) state. The wavy lines denote laser pulses fired from opposite ends of the baseline which are used to divide, direct and recombine the atomic states to yield an interference pattern. Atom-laser interactions are shown as black circles.
• Figure 2: Shot-noise limited projected sensitivity of the single-ion nuclear interferometer configurations detailed in Tab. \ref{['paramsion']} to ULDM with a linear scalar coupling to photons. The curves show the minimum coupling $d_e$ that could be detected at a SNR = 1 following an experimental campaign of duration $T_{\textnormal{int}}=10^8$s. The dotted portion of the curve indicates where the sensitivity may be adversely impacted by magnetic field noise according to the discussion in Sec. \ref{['sec:real']}. Also shown are existing bounds and forecast sensitivities of other experiments as detailed in the main text. The parameter space motivated from a naturalness perspective as described in the text is shown in red.
• Figure 3: Same as Fig. \ref{['fig:deb']} but for ULDM with a linear scalar coupling to gluons.
• Figure 4: Same as Fig. \ref{['fig:deb']} but for ULDM with a linear scalar coupling to quarks.
• Figure 5: Shot-noise limited projected sensitivity of the nuclear interferometer configurations deploying neutral atoms detailed in Tab. \ref{['params_atom']} to ULDM with a linear scalar coupling to photons. The curves show the minimum coupling $d_e$ that could be detected at a SNR = 1 following an experimental campaign of duration $T_{\textnormal{int}}=10^8$ s and assuming that photo-ionisation has been successfully suppressed. The dotted portion of the curve indicates where the sensitivity may be adversely impacted by GGN according to the discussion in Sec. \ref{['sec:real']}. Also shown are existing bounds and forecast sensitivities of other experiments as detailed in the main text. The parameter space motivated from a naturalness perspective as described in the text is shown in red.