Science & Technology

Using the Universe’s Coldest Material in a New Search for Dark Matter

Bose-Einstein condensate comagnetometer, fashioned by two distinct atomic inner states of 87Rb that are contained in the similar spatial wavefunction. Credit score: ICFO/ P. Gomez & M. Mitchell

Scientists have been capable of observe the universe and decide that about 80% of the its mass seems to be “darkish matter,” which exerts a gravitational pull however doesn’t work together with mild, and thus can’t be seen with telescopes. Our present understanding of cosmology and nuclear physics means that darkish matter could possibly be product of axions, hypothetical particles with uncommon symmetry properties.

In a new article revealed in Bodily Assessment Letters and highlighted as an Editor’s suggestion, ICFO researchers Pau Gomez, Ferran Martin, Chiara Mazzinghi, Daniel Benedicto Orenes, and Silvana Palacios, led by ICREA Prof. at ICFO Morgan W. Mitchell, report on the way to search for axions utilizing the distinctive properties of Bose-Einstein condensates (BECs).

The axion, if it exists, would suggest “unique spin-dependent forces.” Magnetism, the best-known spin-dependent pressure, causes electrons to level their spins alongside the magnetic subject, like a compass needle that factors north. Magnetism is carried by digital photons, whereas “unique” spin-dependent forces could be carried by digital axions (or axion-like particles). These forces would act on each electrons and nuclei, and could be produced not simply by magnets, but in addition by bizarre matter. To know if axions do exist, a great way is to look and see if nuclei choose to level towards different matter.

A number of experiments are already looking for these forces, utilizing “comagnetometers,” that are paired magnetic sensors in the similar place. By evaluating the two sensors’ indicators, the impact of the bizarre magnetic subject will be canceled out, leaving simply the impact of the new pressure. To this point, comagnetometers have solely been capable of look for spin-dependent forces that attain about a meter or extra. To look for short-range spin-dependent forces, a smaller comagnetometer is required.

Bose Einstein Condensates (BECs) are gases cooled almost to absolute zero. As a result of BECs are superfluid, their constituent atoms are free to rotate for a number of seconds with none friction, making them exceptionally delicate to each magnetic fields and new unique forces. A BEC can also be very small, about 10 micrometers in dimension. To make a BEC comagnetometer, nonetheless, requires fixing a difficult drawback: the way to put two BEC magnetometers in the similar small quantity.

Of their examine, Gomez and his colleagues report that they had been capable of clear up this drawback by utilizing two totally different inner states of the similar 87Rb BEC, each appearing as a separate however co-located magnetometer. The outcomes of the experiment affirm the predicted excessive immunity to noise from the bizarre magnetic subject and the capability to look for unique forces with a lot shorter ranges than in earlier experiments. In addition to wanting for axions, the approach can also enhance precision measurements of ultracold collision physics and research of quantum correlations in BECs.

Reference: “Bose-Einstein Condensate Comagnetometer” by Pau Gomez, Ferran Martin, Chiara Mazzinghi, Daniel Benedicto Orenes, Silvana Palacios and Morgan W. Mitchell, 29 April 2020, Bodily Assessment Letters.
DOI: 10.1103/PhysRevLett.124.170401

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