Scientists Use Magnetic Levitation to Search for Ultralight Dark Matter

Rice University scientists have developed a sensor that uses magnetic levitation to detect quantum-level oscillations caused by theoretical ultralight dark matter moving through the Earth.

While dark matter is believed to make up most of the matter in the universe, some theories suggest that ultralight dark matter, which behaves like a continuous wave, exerts rhythmic forces that can be detected if the equipment is sensitive enough.

The research team behind the magnetic levitation sensor’s design and construction says their initial tests did not detect ultralight dark matter. However, the experiments, which were supported by the National Science Foundation, provided critical new constraints that will aid ongoing dark matter search efforts.

“Our approach brings dark matter detection into a new realm,” explained Rice University physicist Christopher Tunnell, a postdoctoral researcher and an author on the study detailing the team’s findings.

According to a statement announcing the research, Tunnell and Dorian Amaral, the study’s first author and lead analyst, teamed up with Dennis Uitenbroek and Tjerk Oosterkamp, physicists from Leiden University, to build an ultralight dark matter sensor capable of detecting movements smaller than the width of a hydrogen atom.

First, the team placed a microscopic neodymium magnet inside a superconducting enclosure cooled to near absolute zero. According to Tunnell, by using magnetic levitation to suspend the magnet in this frictionless environment, “we’re giving it the freedom to move if something nudges it.”

After the device was completed, the team began monitoring their magnetically suspended particle for the rhythmic forces caused by ultralight dark matter. If the theories were correct, they hoped to detect interaction forces that differ based on baryon and lepton numbers. Called ‘conserved quantum numbers’ in particle physics, these figures remain constant in particle interactions within a theoretical model known as B−L. This means even the smallest change should be detectable.

According to the team’s statement, their magnetic levitation sensor did not detect the predicted signal of ultralight dark matter interactions. However, Tunnell says their experiments eliminated interactions at the narrow frequency band of around 26.7 Hz targeted by their study, further narrowing the search parameters for future studies.

“Every time we don’t find dark matter, we refine the map,” Tunnell said. “It is like searching for a lost key in your house — when you do not find it in one place, you know to look elsewhere.”

In follow-up experiments, the team says they hope to try something they’ve affectionately titled after the dance the group performed when they met at a climate protest and realized taking such a measurement was even possible: the “Polonaise.” Built using heavier magnets, more stable magnetic levitation, and boasting broader frequency coverage, the team says the Polonaise will probe areas of the theoretical dark matter landscape that current detectors have not explored, “seeking to identify ultra-weak forces in the most undisturbed environments possible.”

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