Searching for dark matter with world’s coldest quantum detectors

One of science’s greatest mysteries may be one step closer to being solved. About 80% of the matter in the universe is dark, meaning it cannot be seen. In fact, dark matter is constantly passing us by—perhaps at a rate of trillions of particles per second.

We know it exists because we can see the effects of its gravity, but experiments to date have failed to detect it.

Using highly advanced quantum technologies, scientists from Lancaster University, University of Oxford and Royal Holloway, University of London are developing the most sensitive dark matter detectors to date.

Their public exhibition entitled „A Quantum View of the Invisible Universe” is on display at this year’s Royal Society’s flagship exhibition. Summer Science Fair 2024 from 2nd to 7th July. There is also related research Published In Journal of Low Temperature Physics.

Researchers Dr. Michael Thompson, Professor Edward Laird, Dr. Dimitri Smev and Dr. from Lancaster. Samuli Atty, Professor Jocelyn Monroe from Oxford and Professor Andrew Casey from RHUL.

EPSRC Fellow Dr. Atty says, „We are using quantum technologies at very low temperatures to develop the most sensitive detectors to date. The goal is to observe this mysterious matter directly in the laboratory and solve one of science’s greatest mysteries.”

There is indirect observational evidence of a regular dark matter density in the galaxy, but the masses of the bulk particles and their possible interactions with ordinary atoms are unknown.

Particle physics theory suggests two possible dark matter candidates: new particles with interactions so weak that we don’t yet observe them, and more light-wave-like particles called axons. The team creates two experiments, one to search for each.

Of the two candidates, new particles with strong-weak interactions could be detected by colliding with ordinary matter. However, whether these collisions can be detected in an experiment depends on the mass of dark matter being sought. Most searches so far can detect dark matter particles weighing between five and 1,000 times that of a hydrogen atom, but much lighter dark matter candidates may have been missed.

The Quantum Enhanced Superfluid Technologies for Dark Matter and Cosmology (QUEST-DMC) group aims to achieve world-leading sensitivity to collisions with dark matter candidates with masses ranging from 0.01 to a few hydrogen atoms. To achieve this, the detector is made of superfluid helium-3, cooled to a macroscopic quantum state and instrumented with superconducting quantum amplifiers. Combining these two quantum technologies creates the sensitivity to measure the very weak signatures of dark matter collisions.

By contrast, if dark matter were created from dust, they would be much lighter — billions of times lighter than a hydrogen atom — but correspondingly more massive. Scientists can’t detect collisions with axons, but instead they can look for another signature — an electrical signal caused by axons disintegrating in a magnetic field.

This effect can only be measured using an elegantly sensitive amplifier that operates at the highest precision allowed by quantum mechanics. The Quantum Sensors for the Hidden Sector (QSHS) group is developing a new type of quantum amplifier that is more suitable for searching for an axial signal.

This year’s exhibition stand will help visitors of all ages track down the unseen with imaginative exhibits.

A gyroscope-in-a-box that moves in surprising ways due to invisible angular momentum will demonstrate how we infer the subject matter from observing galaxies. The liquid also contains transparent glass marbles that show how invisible masses can be observed using clever experimentation.

A light-up dilution refrigerator will demonstrate how the team reaches extremely low temperatures, and a model dark matter particle collider detector will show how our universe would behave if dark matter acted as normal matter.

Visitors can search for dark matter with a model action detector by scanning the frequency of a radio receiver, and they can build their own parametric amplifier with a pendulum.

Cosmologist Carlos Frank, Fellow of the Royal Society and Chair of the Public Engagement Committee, said: „Science is vital to our understanding of the world we live in, past, present and future. I invite visitors of all ages to come with an open mind, be curious and excited, and celebrate the incredible scientific achievements that benefit us all.”