A New Quantum Crystal May Finally Reveal the Nature of Dark Matter

And unravel a cosmic mystery.
Brad Bergan
An abstract image of data and fiber optics.SpiffyJ / iStock

Not all crystals are science fiction.

Scientists created a new quantum crystal sensor that could hold the key to detecting the presence of dark matter, according to a new study published in the journal Science.

With most of the universe composed of dark matter, discovering its nature could unravel one of the oldest mysteries in astronomy.

A new quantum crystal has '10 times the sensitivity' of earlier demonstrated ones

Specifically, physicists from the National Institute of Standards and Technology (NIST) have grouped, or "entangled," the electronic properties and mechanical motion of a very tiny blue crystal, which enables it to measure electric fields with record sensitivity that could substantially deepen our grasp of the universe. The new quantum sensor confines 150 beryllium ions in a magnetic field, enabling them to self-arrange into a flat, 2D crystal only 200 millionths of one meter in diameter. This kind of quantum sensor could potentially reveal signs of dark matter, which is a mysterious substance comprising most of the universe, and might be composed of subatomic particles that affect normal matter via a weak electromagnetic field.

If dark matter is detected, the mechanism of detection would involve wiggling in the crystal, observed in collective changes in its ions via one of their electronic properties, called spin. Researchers can detect vibrational excitation, also called displacement. The so-called "dark matter sensor" can monitor and measure external electric fields possessing the same vibration frequency as the crystal, with a sensitivity more than 10 times that of any atomic sensor demonstrated in the past. During their experiments, researchers used a weak electric field to excite the crystal and test the sensor. "Ion crystals could detect certain types of dark matter — examples are axions and hidden photons — that interact with normal matter through a weak electric field," said John Bollinger of NIST, who was also senior author of the study, in an embargoed release shared with IE.

The nature of dark matter could unravel the mysteries of the universe

"The dark matter forms a background signal with an oscillation frequency that depends on the mass of the dark matter particle," continued Bollinger. "Experiments searching for this type of dark matter have been ongoing for more than a decade with superconducting circuits. The motion of trapped ions provides sensitivity over a different range of frequencies." Bollinger and his colleagues have worked on the new ion crystal for more than a decade, and only recently added the use of a laser light to entangle the collective spins and motions of a large number of ions, which, in addition to something called "time reversal" strategy, enhanced the method of detecting dark matter.

The novel experiment went forward with help from the NIST theorist Ana Maria Rey, who is with JILA, a joint institute of the University of Colorado Boulder, and NIST. Rey's theoretical work was crucial to the team's ability to grasp the limits of a laboratory setup, in addition to providing a new model for understanding which experiment might provide valid results for large numbers of trapped ions. Her work also proved that the quantum advantage comes from entangling the motion and spin, according to Bollinger.

"We know 85% of the matter in the universe is made of dark matter, but to date we do not know what dark matter is made of," said Rey, in the embargoed release. "This experiment could allow us in the future to unveil this mystery." And, once we understand the nature of dark matter, a wide span of scientific disciplines, including astrophysics, astronomy, cosmology, and more could create models and descriptions of the universe that could dwarf current models in terms of both explanatory power and sheer, unmitigated awe.

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