Scientists use world’s coldest quantum detectors to search for dark matter

The experiment is at about a 10000th of a degree above absolute zero in a special refrigerator ; Dr. Autti (right). Credit: Lancaster University.

One of the greatest mysteries in science might be closer to being solved thanks to the coldest quantum detectors ever built.

Scientists estimate that about 80% of the matter in the universe is dark matter, which is invisible and passes through us constantly—possibly trillions of particles per second.

We know dark matter exists because we can see the effects of its gravity, but no one has been able to detect it directly yet.

Researchers from Lancaster University, the University of Oxford, and Royal Holloway, University of London are using advanced quantum technologies to build the most sensitive dark matter detectors to date.

Their project, “A Quantum View of the Invisible Universe,” is being showcased at this year’s Royal Society Summer Science Exhibition from July 2–7, 2024.

Their related research is also published in the Journal of Low Temperature Physics.

The team includes Dr. Michael Thompson, Professor Edward Laird, Dr. Dmitry Zmeev, and Dr. Samuli Autti from Lancaster, Professor Jocelyn Monroe from Oxford, and Professor Andrew Casey from RHUL. Dr. Autti explains, “We are using quantum technologies at ultra-low temperatures to create the most sensitive detectors ever. Our goal is to observe dark matter directly and solve one of science’s greatest puzzles.”

Scientists have indirect evidence of dark matter’s presence in the galaxy, but they do not know the mass of its particles or how these particles might interact with ordinary atoms. There are two main candidates for dark matter particles: new particles with very weak interactions and very light wave-like particles called axions. The team is building experiments to search for both types.

For the first type, new particles with ultra-weak interactions might be detected through collisions with ordinary matter. These particles could weigh between five and 1,000 times more than a hydrogen atom. However, lighter particles might have been missed in previous searches. The QUEST-DMC team is developing a detector made of superfluid helium-3, which is cooled to a quantum state and equipped with superconducting quantum amplifiers. This setup aims to detect dark matter particles with a mass between 0.01 to a few hydrogen atoms.

For axions, which are extremely light but very abundant, scientists cannot detect collisions but can look for an electrical signal produced when axions decay in a magnetic field. The QSHS team is creating a highly sensitive quantum amplifier to search for this signal.

At the exhibition, visitors can explore dark matter through interactive exhibits. They can see a gyroscope that moves in surprising ways to represent unseen forces and glass marbles that become visible in liquid, showing how clever experiments can reveal hidden objects. A light-up dilution refrigerator will demonstrate how ultra-low temperatures are achieved, and a model dark matter particle collision detector will show how the universe might behave if dark matter were like normal matter.

Visitors can also use a model axion detector to search for dark matter by tuning a radio receiver and create their own parametric amplifier with a pendulum.

Cosmologist Carlos Frenk encourages everyone to visit the exhibition, saying, “Science helps us understand our world—past, present, and future. I invite visitors of all ages to come with curiosity and enthusiasm to celebrate incredible scientific achievements that benefit us all.”