Scientists use two new quantum methods to capture suspected dark matter

The search for dark matter is about to get a lot colder. Scientists are developing supercold quantum technology to hunt down the most elusive and mysterious things in the universe, which currently constitutes one of the greatest mysteries in science.

Despite the fact that dark matter exceeds the amount of ordinary matter in our universe by about six times, scientists don’t know what it is. This is, at least in part, because no experiment developed by humanity has been able to detect it.

To solve this enigma, scientists from several UK universities came together as a team to build two of the most sensitive dark matter detectors already imagined. Each experiment will look for a different hypothetical particle that could comprise dark matter. Although they have some of the same qualities, the particles also have some radically different characteristics, thus requiring different detection techniques.

The equipment used in both experiments is so sensitive that components need to be cooled to a thousandth of a degree above absolute zero, the theoretical and unattainable temperature at which all atomic movement would cease. This cooling must occur to avoid interference, or “noise”, from the world that corrupts the measurements.

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“We are using quantum technologies at ultra-low temperatures to build the most sensitive detectors to date,” said team member Samuli Autti from Lancaster University. said in a statement. “The goal is to observe this mysterious subject directly in the laboratory and solve one of the greatest enigmas in science.”

How dark matter left scientists out in the cold

Dark matter represents a major problem for scientists because, despite representing around 80% to 85% of the universe, remains effectively invisible to us. This is because dark matter does not interact with light or “everyday” matter – and if it does, these interactions are rare or very weak. Or maybe both. We simply don’t know.

However, because of these characteristics, scientists know that dark matter cannot be composed of electrons, protons It is neutrons — all part of the baryon family of particles that make up everyday matter in things like stars, planets, moons, our bodies, ice cream, and the neighbor’s cat. All the “normal” things we can see.

The only reason we think dark matter actually exists is that this mysterious substance has mass. Thus, it interacts with gravity. Dark matter can influence the dynamics of ordinary matter and light through this interaction, allowing us to infer its presence.

Astronomer Vera Rubin discovered the presence of dark matter, previously theorized by scientist Fritz Zwicky, because he saw some galaxies spinning so fast that if their only gravitational influence came from visible baryonic matter, they would fly apart. What scientists really want, however, is not an inference but rather a positive detection of dark matter particles.

One of the hypothetical particles currently postulated as the prime suspect for dark matter is light itself.”axion.” Scientists also theorize that dark matter may be composed of new, more massive particles (as yet unknown) with interactions so weak that we have not yet observed them.

Both axions and these unknown particles would exhibit ultraweak interactions with matter, which could theoretically be detected with sufficiently sensitive equipment. But two prime suspects means two investigations and two experiments. This is necessary because current dark matter research generally focuses on particle masses between 5 times and 1,000 times the mass of a hydrogen atom. This means that if dark matter particles are lighter, they could be being lost.

The Quantum Enhanced Superfluid Technologies for Dark Matter and Cosmology (QUEST-DMC) experiment was developed to detect ordinary matter colliding with dark matter particles in the form of unknown new weakly interacting particles that have masses between 1% and sometimes that of a hydrogen atom. QUEST-DMC uses superfluid helium-3, a light and stable isotope of helium with a nucleus of two protons and one neutron, cooled into a macroscopic quantum state to achieve record sensitivity in detecting ultraweak interactions.

However, QUEST-DMC would not be able to detect extremely light axions, which theoretically have masses billions of times lighter than a hydrogen atom. This also means that such axions would not be detectable by their interaction with particles of ordinary matter.

However, what they lack in mass, axions are claimed to make up for in numbers, with these hypothetical particles suggested to be extremely abundant. That means it’s best to look for these dark matter suspects using a different signature: the tiny electrical signal resulting from the decay of axions in a magnetic field.

If such a signal exists, detecting it would require stretching the detectors to the maximum level of sensitivity allowed by the rules of quantum physics. The team hopes its quantum sensors for the hidden sector (QSHS) would be able to do just that.

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If you are in the UK, the public can view the QSHS and QUEST-DMC experiments at Lancaster University Summer Science Exhibition. Visitors will also be able to see how scientists infer the presence of dark matter in galaxies using a gyroscope in a box that moves strangely due to invisible angular momentum.

Additionally, the exhibit features an illuminated dilution refrigerator to demonstrate the ultra-low temperatures required by quantum technology, while its dark matter particle collision detector model shows how our universe would behave if dark matter interacted with matter and light, just as everyday matter does.

The team’s papers detailing the QSHS and QUEST-DMC experiments were published in the journal The European Physical Journal C and on the paper repository website arXiv.