Dark matter makes up around 27% of the universe, yet no one has ever seen it. Scientists know dark matter exists because it has gravitational effects on spinning galaxies, but the world’s most sensitive sensors have yet to detect it. Now a team of researchers has developed a quantum crystal that can detect the smallest electromagnetic forces.
The discovery could one-day help scientists in unravelling the nature of dark matter and resolving one of the universe’s greatest mysteries.
A team of scientists from the University of Colorado Boulder and the National Institute of Standards and Technology in the US have developed a quantum crystal by using magnetic fields to trap 150 charged particles or ions of beryllium.
The magnetic fields assisted in overcoming the particles’ intrinsic repulsion, allowing the ions to form a structure twice the thickness of a human hair.
The final arrangement resembled the shape of a crystal and, more crucially, vibrated when subjected to an external force.
Ana Maria Rey, a physicist at the JILA research institute in Colorado, told Live Science: “When you excite atoms, they don’t move individually. They move as a whole.”
The movements of the quantum crystal, according to the researchers, might be utilized to detect the strength of an electromagnetic field.
Many hypotheses about the nature of black matter have been proposed, including theories involving undetectable black holes and gravity seeping from another dimension.
However, one of the most common theories is that dark matter is a yet-to-be-discovered particle, and experiments at CERN’s Large Hadron Collider (LHC) are attempting to verify this.
However, before applying the quantum crystal to look for dark matter, the researchers had to overcome a major quantum mechanics quirk.
Scientists cannot exactly estimate the position and momentum of particles due to the so-called Heisenberg uncertainty principle.
The more precisely a particle’s position is measured, the less certain its momentum is, and vice versa.
The JILA scientists solved this challenge by employing quantum entanglement, a strange phenomenon in which the states of two or more items are linked even though they are at opposite ends of the universe.
Professor Rey said: “By using entanglement, we can sense things that aren’t possible otherwise.”
The scientist and her colleagues linked the beryllium particles’ movements with their spin.
Then, when the quantum crystal vibrated as a result of having an electromagnetic field passed through it, it would move a certain amount.
However, due to the uncertainty principle, attempting to measure the displacement or the number of beryllium particles moved would generate a large amount of quantum noise.
The scientists were able to spread out the noise by entangling the spins of the particles, allowing for readings that are ten times more exact than existing quantum sensors.
And Professor Rey and her team think they can make an even more sensitive detector.
But what does all of this mean for dark matter? According to one theory, dark matter may be explained through the discovery of axions – hypothetical elementary particles proposed in the late Seventies.
These theoretical particles could have the mass of a millionth or billionth of an electron, which could explain why they have eluded us for so long.
According to some predictions, axions may at times convert into photons.
If this is the case, the particles would no longer be “dark” but give off a faint electromagnetic field.
Should any axions fly through the quantum crystal detector, there is a chance scientists could detect their presence.
The results of the study were published this month in the journal Science.
Image Credit: GEtty