by The pursuit of dark matter is about to get a lot cooler. Scientists are developing super-cool quantum technology to search for the most elusive and mysterious things in the universe, which is one of the biggest mysteries in science right now.
Despite the fact that there is six times more dark matter than normal matter in our Universe, scientists do not know what it is. That’s at least in part because no experiment devised by mankind has ever been able to detect it.
To tackle this challenge, scientists from several universities across the UK teamed up to build two of the most sensitive dark matter detectors ever imagined. Each experiment will look for a different hypothetical particle that could contain dark matter. Although they share some of the same qualities, the particles have radically different characteristics, requiring different detection techniques.
The equipment used in both experiments is so sensitive that the components must be cooled to a thousandth of a degree above absolute zero, the theoretical and unattainable temperature at which all atomic motion would cease. This cooling must occur to prevent interference, or “noise,” from ground pollution 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 of Lancaster University in a statement. “The goal is to observe this mysterious material directly in the laboratory and solve one of the biggest enigmas in science.”
How dark matter scientists left out in the cold
Dark matter is a big question for scientists because, despite making up about 80% to 85% of the universe, it is effectively invisible to us. This is because dark matter does not interact with light or “everyday” matter – and, if it does, those interactions are rare or very weak. Or maybe both. We just don’t know.
However, because of these characteristics, scientists know that dark matter cannot consist of electrons, protons and neutrons – all part of the baryon family of particles that make up everyday matter in objects like stars , planets, moons, our bodies, ice cream. and a cat next door. All the “normal” things we can see.
The only reason we think dark matter exists at all, in fact, is because this mysterious substance has mass. Therefore, it interacts with gravity. Dark matter can influence the dynamics of normal matter and light through that interaction, making it possible to infer its presence.
Astronomer Vera Rubin discovered the existence of dark matter, previously theorized by scientist Fritz Zwicky, because she saw certain galaxies spinning so fast that their only gravitational influence came from visible, baryonic matter , that they would fly apart. What scientists really want, however, is not an inference but a positive detection of dark matter particles.
One of the hypothetical particles that is currently the prime suspect for dark matter is the very light “axion”. Scientists also theorize that dark matter may consist of new, more massive particles (as yet unknown) whose interactions are so weak that we haven’t noticed them yet.
Both axes and the 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 searches for dark matter focus on particles with masses between 5 and 1,000 times the mass of a hydrogen atom. That means, if dark matter particles are lighter, they may be getting lost.
The Quantum Superfluid Technologies for Dark Matter and Cosmology (QUEST-DMC) experiment is designed to detect normal matter colliding with dark matter particles in the form of new, weakly interacting unknown particles with masses between 1% and several times more more than 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 to a macroscopic quantum state to achieve superfluid sensitivity for observing ultraweak interactions.
QUEST-DMC would not be able to see extremely light axes, however, whose masses are theorized to be billions of times lighter than a hydrogen atom. This also means that such axes would not be detectable through their interaction with particles of ordinary matter.
However, although they have no mass, axes have been determined to make up a number, and these hypothetical particles are proposed to be very abundant. That means it’s better to search for dark matter suspects using a different signature: the tiny electrical signal that results from decaying axes in a magnetic field.
If such a signal exists, detectors would need to be stretched to the maximum level of sensitivity allowed by the rules of quantum physics to detect it. The team hopes that their Quantum Sensors for the Hidden Sector A quantum amplifier (QSHS) would be able to do that.
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If you are in the UK, the public can see both the QSHS and QUEST-DMC experiments at Lancaster University’s 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 unprecedented angular momentum.
In addition, the exhibit features a light-dilution refrigerator to demonstrate the ultra-low temperatures required by quantum technology, and its dark matter particle collision detector shows how our Universe would behave if dark matter interacted with matter and light just like normal matter does.
The team’s papers detailing the QSHS and QUEST-DMC experiments have been published in The European Physical Journal C and on the paper repository site arXiv.
