Optics & Photonics

A millimeter-wave sensing experiment for investigating ultra-light dark matter

The biblical Goliath could have been defeated in a number of different ways, but David chose to use a small stone and a slingshot to attack.

In a similar vein, scientists have attempted to unravel the mystery of dark matter—which accounts for roughly one fourth of the universe—by recording its gravitational effects on visible matter rather than directly observing it.

Utilizing a technology for millimeter-wave sensing in cryogenic conditions that is characterized by low thermal noise, a group of researchers from Kyoto University have now established an experimental method for examining ultra-light dark matter at 0.1 millielectron volts. The paper has been accepted for publication in Physical Review Letters.

Lead author Shunsuke Adachi states, “We achieved experimental parameters for an unexplored mass range of dark photon dark matter—or DPDM—by using new techniques previously untested in this field.”

“Our research on millimeter-wave technologies may accelerate the development of future telecommunications such as 5G and 6G,”

Lead author Shunsuke Adachi.

It has been hypothesized that the mass of a single dark matter particle is greater than that of a proton. The extremely difficult challenge of detecting ultra-low-mass dark matter, which has eluded scientists for more than three decades, is addressed by Adachi’s team’s search.

Adachi adds, “Our research on millimeter-wave technologies may advance advanced telecommunications such as 5G and 6G.”

To accommodate weak conversion photons, a millimeter-wave receiver is cooled to -270 °C to reduce thermal noise. This cryogenic receiver is used to look for DPDMs with a mass range of about 0.1 meV. Adachi says that even though his team didn’t find any significant signals in this dataset, they could have looked into dark matter by conducting their experiments under constraints that were tighter than those in cosmology.

Metal plate surfaces could theoretically be used to convert dark photons into ordinary photons. These transformation photons compare to the mass of dim photons in view of energy protection. “We are thrilled that our small team was able to obtain important results from our high-sensitivity experiments for detecting DPDMs in an unexplored mass range,” Adachi states. “Conversion photon frequency of 10–300 GHz corresponds to dark photon mass of 0.05–1 meV.”

More information: S. Kotaka et al, Search for Dark Photon Dark Matter in the Mass Range 74–110 μeV with a Cryogenic Millimeter-Wave Receiver, Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.130.071805

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