Hunting for topological dark matter with atomic clocks

Abstract: The cosmological applications of atomic clocks so far have been limited to searches of the uniform-in-time drift of fundamental constants. In this paper, we point out that a transient in time change of fundamental constants can be induced by dark matter objects that have large spatial extent, and are built from light non-Standard Model fields. The stability of this type of dark matter can be dictated by the topological reasons. We point out that correlated networks of atomic clocks, some of them already in existence, can be used as a powerful tool to search for the topological defect dark matter, thus providing another important fundamental physics application to the ever-improving accuracy of atomic clocks. During the encounter with a topological defect, as it sweeps through the network, initially synchronized clocks will become desynchronized. Time discrepancies between spatially-separated clocks are expected to exhibit a distinct signature, encoding defect's space structure and its interaction strength with the Standard Model fields.

• The paper introduces a novel method where atomic clocks measure transient time variations caused by topological dark matter defects.
• The authors correlate desynchronization in spatially distributed clocks with the passage of dark matter, achieving sensitivity to energy scales up to 10 TeV.
• The experimental framework proposes terrestrial and satellite network deployments to refine constraints on new physics beyond the Standard Model.

Insights into the Use of Atomic Clocks for Detecting Topological Dark Matter

The paper by Derevianko and Pospelov introduces an innovative approach utilizing atomic clocks for the detection of topological dark matter (TDM). The authors focus on the potential of atomic clocks organized in a network to identify transient time variations of fundamental physical constants induced by TDM, primarily manifesting through topological defects such as monopoles, strings, and domain walls.

Core Concept and Methodology

The study's central thesis rests on the premise that atomic clocks, renowned for their unprecedented precision, can serve as sensitive detectors for the temporal disruptions caused by dark matter interactions. These disruptions are hypothesized to occur when large-scaled dark matter entities, such as topological defects, pass through the clocks' network. The encounter is expected to induce a detectable desynchronization between clocks, attributed to a transient but measurable change in physical constants.

The authors elaborate on the theoretical framework by introducing light fields beyond the Standard Model, forming topological defects. These defects are transient, macroscopic configurations of light fields that can potentially modulate fundamental constants like the fine structure constant ($\alpha$) via interactions at the quantum level, described by various "portals." The interaction detailed involves quadratic scalar portals leading to variations in masses and couplings through quadratic terms, avoiding more stringent constraints from existing gravitational experiments.

Experimental Setup and Expected Outcomes

The detection relies on correlating time discrepancies between spatially dispersed atomic clocks. As a topological defect transverses the network, its footprint would be registered as a phased time anomaly, distinguishable from standard noise and perturbations. The paper describes an experimental arrangement using both microwave and optical clocks, with potential deployments including terrestrial and satellite-based networks such as the Global Positioning System (GPS). The framework predicts that changes in clock synchronization due to the transient effects of TDM could provide an observable signature, depending heavily on the defect's size, density, and interaction strength.

Results Interpretation and Implications

One of the paper's key results is a derived expression for the signal-to-noise ratio for detecting TDM signatures. This expression establishes the dependence on parameters like the topological defect's size, interaction strength, and the characteristic scales of fundamental constants. The study speculatively indicates that parameters such as the Compton wavelength of the field and the energy scales, denoted as $\Lambda_X$, are critical for determining the probability and nature of detectable encounters.

The research suggests that leveraging the precision of atomic clocks could extend constraints on dark matter interactions beyond those currently achievable through direct laboratory and astrophysical methods. Specifically, the proposed approach offers sensitivity to new physics at energy scales up to 10 TeV, surpassing existing constraints for dark matter searches.

Future Directions

Population of the detection network with multiple clock types is recommended to disentangle the mixed signatures across various fundamental constants. Moreover, the proposed strategy could be scaled by increasing the number of clock network nodes and utilizing alternative clock technologies. Theoretical advancements can also be anticipated in calculating detailed network optimization strategies to enhance detection sensitivity and differentiating dark matter characteristics.

Conclusion

This paper provides a compelling case for expanding the role of precision measurement technologies in fundamental physics research. By potentially opening a direct method of probing non-standard cosmological fields, the application of atomic clocks in dark matter searches represents a promising frontier. Future experiments, stemming from the paper's findings, may offer novel insights into the dark sector and a better understanding of the universe's non-luminous constituents.