Scientists have proposed a novel method for detecting gravitational waves —the faint ripples in spacetime predicted by Albert Einstein —by repurposing the powerful magnets used in dark matter experiments. According to new research in Physical Review Letters, these magnets can act as highly sensitive “magnetic Weber bars,” opening an entirely new frequency range for observing the cosmos. The concept modernizes the original Weber bar, a device from the 1960s that used large metal cylinders designed to physically ring like a bell when struck by a gravitational wave, but which was primarily limited to specific resonant frequencies. This new approach promises to detect signals across a much broader spectrum, potentially unveiling previously unseen cosmic events.

The detection method relies on the fundamental interaction between gravity and electromagnetism. A gravitational wave passing through a strong, steady magnetic field, known as a direct current (DC) field, causes the entire magnet structure to oscillate minutely. This includes the superconducting wires that carry the electrical current, generating the field. As these wires vibrate, they produce a tiny new signal in the form of an oscillating magnetic field, also known as an alternating current (AC) component. This faint signal, which carries the signature of the passing gravitational wave, can then be measured by extremely sensitive detectors called Superconducting Quantum Interference Devices, or SQUIDs, which are designed to detect minuscule changes in magnetic fields.

This innovative technique offers a significant advantage by leveraging the infrastructure of cutting-edge particle physics experiments. Projects such as the Dark Matter Radio and ADMX-EFR, which hunt for a hypothetical dark matter particle called the axion, already use the massive superconducting magnets ideal for this purpose. The researchers calculate that the magnet for the ADMX-EFR experiment could achieve a broadband gravitational wave strain sensitivity of approximately 10⁻²⁰/√Hz. This would enable it to operate in the largely unexplored high-frequency window, spanning from a few kilohertz to approximately 10 megahertz —a range where it could outperform current detectors, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO).

While the concept is promising, significant engineering challenges remain, chief among them isolating the detector from environmental vibrations on Earth that could mimic a gravitational wave signal. This is a familiar problem in the field, as observatories like LIGO have developed sophisticated systems to overcome similar interference. By piggybacking on the search for dark matter, scientists hope to augment the scientific return of these experiments, effectively searching for two of the universe’s greatest mysteries with a single instrument. If successful, these magnetic detectors could provide an unprecedented view into high-frequency gravitational events, such as those from primordial black holes or other exotic cosmic phenomena.

References

• Domcke, V., Ellis, S. A. R., & Rodd, N. L. (2025). Magnets are weber bar gravitational wave detectors. Physical Review Letters, 134(23), 231401. https://doi.org/10.1103/966v-r5fm

• Gururaj, T. & Phys.org. (2025, June 28). Powerful magnets could unlock detection of high-frequency gravitational waves. Phys.Org; Phys.org. https://phys.org/news/2025-06-powerful-magnets-high-frequency-gravitational.html