Superconducting Magnets as New Gravitational Wave Detectors

New research published in Physical Review Letters suggests that superconducting magnets used in dark matter detection experiments could function as highly precise gravitational wave detectors, thereby establishing an entirely new frequency band for observing these cosmic ripples.

This concept expands on the initial Weber bar architecture from the 1960s, in which Joseph Weber proposed detecting gravitational waves using massive metal cylinders that would respond through mechanical resonance.

Although Weber's technique succeeded at certain resonant frequencies, it experienced reduced sensitivity outside these restricted frequency bands.

This study extends this concept, demonstrating that DC magnets can function as magnetic Weber bars, potentially detecting gravitational waves in the previously challenging kilohertz to megahertz frequency range.

Phys.org spoke to co-author Dr. Sebastian Ellis from the University of Geneva about the research, which he conducted with Valerie Domcke from CERN and Nicholas L. Rodd from Lawrence Berkeley National Laboratory.

The new magnetic approach addresses this fundamental limitation by leveraging the enormous magnetic energy stored in superconducting magnets, which far exceeds the electric energy available in traditional Weber bar readout systems.

The detection mechanism relies on a clever two-step interaction between gravitational waves and magnetic fields.

A gravitational wave passing through a superconducting magnet induces microscopic vibrations across the entire structure, analogous to the barely perceptible motion of LIGO's mirrors.

These deformations create an oscillating magnetic field component that researchers can detect using extraordinarily sensitive quantum sensors called SQUIDs (Superconducting Quantum Interferometric Devices).

The approach offers several key advantages over traditional methods.

The research specifically highlights powerful magnets being constructed for axion dark matter experiments, including DMRadio and ADMX-EFR (Axion Dark Matter eXperiment—Extended Frequency Range).

The researchers estimated that the sensitivity of these MRI magnets would be somewhat lower than LIGO's peak performance. However, it would operate across a much broader frequency range, from a few kilohertz to about 10 megahertz.

This frequency range represents largely uncharted territory for gravitational wave astronomy.

Converting this concept into working detectors will require overcoming significant technical hurdles, particularly in isolating the instruments from environmental vibrations that could mimic gravitational wave signals.

The team is now expanding their collaboration and studying specific gravitational wave signals that could be detected with operational magnetic Weber bars. They're also exploring advanced quantum sensing techniques beyond SQUIDs that could further enhance sensitivity.

According to the source: Phys.org.