Searching for Dark Matter with an Optical Cavity and an Unequal-Delay Interferometer

Abstract

We propose a new type of experiment that compares the frequency of a clock (an ultrastable optical cavity in this case) at time t to its own frequency some time t-T earlier, by "storing" the output signal (photons) in a fiber delay line. In ultralight oscillating dark matter (DM) models, such an experiment is sensitive to coupling of DM to the standard model fields, through oscillations of the cavity and fiber lengths and of the fiber refractive index. Additionally, the sensitivity is significantly enhanced around the mechanical resonances of the cavity. We present experimental results of such an experiment and report no evidence of DM for masses in the [4.1 × 10 −11 , 8.3 × 10 −10 ] eV region. In addition, we improve constraints on the involved coupling constants by one order of magnitude in a standard galactic DM model, at the mass corresponding to the resonant frequency of our cavity. Furthermore, in the model of relaxion DM, we improve on existing constraints over the whole DM mass range by about one order of magnitude, and up to 6 orders of magnitude at resonance.

Search for oscillations of fundamental constants using molecular spectroscopy

“…We find that in this sector of coupling space the bounds related to our direct UDM experiments are only two to three orders weaker than the bounds from the EP tests. Existing constraints: shaded regions in orange [34], yellow [35], pink [29], green [53], Magenta [37], and purple [67]. Fifth-force/EP tests: turquoise [59,60,[64][65][66].…”

“…In contrast to EP-violating acceleration searches, direct scalar-UDM experiments probe observables in either quantum or macroscopic systems arising due to the dependence of atomic transition energies, the length of solid objects, or the refractive indices of materials on the FCs. For a review, see, for example, [17], for proposals, see [18][19][20][21][22][23][24][25][26][27], and for experiments providing bounds on FC oscillations see [28][29][30][31][32][33][34][35][36][37]. The sensitivities of different kinds of experiments are intrinsically different.…”

“…Such enhancement would not, however, apply to fifth-force experiments, as in these, the test masses exchange virtual DM particles, a process independent of the background DM density. In recent experiments searching for FC oscillations, the investigated parameter space was extended to frequencies higher than 1 Hz, to cover the audio and radiofrequency (RF) range [29,30,34,35].…”

“…Figure 4. Exclusion plot of the coupling to (a) α and (b) me.Existing constraints: shaded regions in orange[34], yellow[35], pink[29], green[53], Magenta[37], and purple[67]. Fifth-force/EP tests: turquoise[59,60,[64][65][66].…”

Gravitational Focusing of Wave Dark Matter

“…For instance, ADMX[49][50][51], HAYSTAC[52,53], ABRA-CADABRA[54,55], DM-Radio[56], CAPP[57], MADMAX[58] and so on 2. For instance, atomic clocks[59][60][61][62][63][64], atomic and molecular spectroscopy searches[65,66], and interferometry[67][68][69].…”