Detecting dark-matter waves with a network of precision-measurement tools

Abstract

Virialized Ultra-Light Fields (VULFs) are viable cold dark matter candidates and include scalar and pseudo-scalar bosonic fields, such as axions and dilatons. Direct searches for VULFs rely on low-energy precision measurement tools. While the previous proposals have focused on detecting coherent oscillations of the VULF signals at the VULF Compton frequencies at individual devices, here I consider a network of such devices. VULFs are essentially dark matter waves and as such they carry both temporal and spatial phase information. Thereby, the discovery reach can be improved by using networks of precision measurement tools. To formalize this idea, I derive a spatio-temporal two-point correlation function for the ultralight dark matter fields in the framework of the standard halo model. Due to VULFs being Gaussian random fields, the derived two-point correlation function fully determines N -point correlation functions. For a network of ND devices within the coherence length of the field, the sensitivity compared to a single device can be improved by a factor of √ ND. Further, I derive a VULF dark matter signal profile for an individual device. The resulting line shape is strongly asymmetric due to the parabolic dispersion relation for massive non-relativistic bosons. I discuss the aliasing effect that extends the discovery reach to VULF frequencies higher than the experimental sampling rate. I present sensitivity estimates and develop a stochastic field SNR statistic. Finally, I consider an application of the developed formalism to atomic clocks and their networks. arXiv:1605.09717v3 [physics.atom-ph]

Applying the matched-filter technique to the search for dark matter transients with networks of quantum sensors

“…Additionally, certain simplifications can be obtained using discrete Fourier transformation (DFT) (see, e.g., Ref. [21], where DFT for a network covariance matrix was carried out). In DFT, the transformed matrix becomes block-diagonal, each block being of dimension N D , thus simplifying the inversion procedure.…”

“…A related theoretical development for ultralight (non self-interacting) DM fields is presented in Ref. [21]. There a quantum sensor network was considered for detecting DM waves and a SNR statistic was developed in the frequency domain.…”

Searching for Scalar Dark Matter with Compact Mechanical Resonators

“…Scalar DM field properties-DM particles in the Milky Way have a Maxwellian velocity distribution about the virial velocity v vir ≈ 10 −3 c [53]. Given the local DM density (ρ dm ≈ 0.3 GeV/cm 3 [54]), ultralight DM particles behave as a classical field.…”

“…Given the local DM density (ρ dm ≈ 0.3 GeV/cm 3 [54]), ultralight DM particles behave as a classical field. We consider DM as a field with coherence time τ c = vvir 2 c 2 ω dm −1 and coherence length λ c equal to the de Broglie wavelength λ dm [53]. DM mass m dm 10 −6 eV corresponds to λ dm 1 km, implying that the field is spatially uniform over laboratory scales.…”

“…This effect introduces an isotropic stress in a solid body (rather, any form of condensed phase matter). This stress is effectively spatially uniform over length scales much smaller than λ c [53]. Such a periodic stress may excite acoustic vibrations in the body.…”