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NASA demonstrates a new quantum tool called an atom interferometer, which can accurately measure gravity.

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NASA’s Cold Atom Lab, a pioneering facility on the International Space Station, has advanced the potential of quantum science in space. The science team has used one of the lab’s tools to measure subtle vibrations of the space station — marking the first use of ultra-cold atoms to detect environmental changes in space.

Published in Nature Communications on Aug. 13, the study also showcases the longest demonstration of atoms’ wave-like behavior in freefall in space.

The team utilized a quantum tool called an atom interferometer, which can accurately measure gravity, magnetic fields, and other forces. On Earth, this tool helps scientists study gravity and improve technologies for aircraft and ship navigation. (Other major technologies like cell phones, transistors, and GPS are based on quantum science but do not use atom interferometry.)

Physicists have been keen to use atom interferometry in space due to the microgravity environment, which allows for longer measurement times and enhanced sensitivity. However, the equipment has been considered too delicate for long-term operation without manual support. The Cold Atom Lab, operated remotely from Earth, has now proven it can function effectively.

“Reaching this milestone was incredibly challenging, and our success was not always a given,” said Jason Williams, the Cold Atom Lab project scientist at NASA’s Jet Propulsion Laboratory in Southern California. “It took dedication and a sense of adventure by the team to make this happen.”

Power of Precision

Space-based sensors that measure gravity with high precision have numerous potential applications. For example, they could uncover the composition of planets and moons in our solar system due to the varying densities of different materials, which create subtle variations in gravity.

The U.S.-German collaboration GRACE-FO (Gravity Recovery and Climate Experiment Follow-on) is already performing this type of measurement, detecting slight changes in gravity to track the movement of water and ice on Earth. An atom interferometer could enhance this precision and stability, providing more detailed insights into surface mass changes.

Accurate gravity measurements could also shed light on the nature of dark matter and dark energy, two significant cosmological mysteries. Dark matter is an invisible substance that is five times more common in the universe than the “regular” matter composing planets, stars, and everything else we can see. Dark energy refers to the unknown force driving the universe’s accelerating expansion.

“Atom interferometry could also be used to test Einstein’s theory of general relativity in new ways,” said University of Virginia professor Cass Sackett, a Cold Atom Lab principal investigator and co-author of the new study. “This is the basic theory explaining the large-scale structure of our universe, and we know that there are aspects of the theory that we don’t understand correctly. This technology may help us fill in those gaps and give us a more complete picture of the reality we inhabit.”

A Portable Lab

NASA’s Cold Atom Lab examines the quantum nature of atoms, the fundamental components of our universe, aboard the International Space Station. This animated explainer delves into what quantum science is and why NASA conducts these studies in space. Credit: NASA/JPL-Caltech

Roughly the size of a mini-fridge, the Cold Atom Lab launched to the space station in 2018 with the aim of advancing quantum science in the microgravity environment of low Earth orbit. The lab cools atoms to nearly absolute zero, or minus 459 degrees Fahrenheit (minus 273 degrees Celsius). At this temperature, certain atoms can form a Bose-Einstein condensate, a state of matter where all atoms share the same quantum identity. This makes some of the atoms’ usually microscopic quantum properties observable on a macroscopic scale, making them easier to study.

Quantum properties can include behaving as both solid particles and waves. Scientists are still exploring how these fundamental components of matter transition between such different physical behaviors, using quantum technology like that in the Cold Atom Lab to find answers.

In microgravity, Bose-Einstein condensates can achieve colder temperatures and last longer, providing scientists with more opportunities for study. The facility includes tools like the atom interferometer, which enables precise measurements by leveraging the quantum nature of atoms.

Thanks to its wave-like behavior, a single atom can travel along two separate paths simultaneously. If gravity or other forces affect these waves, scientists can measure the impact by observing how the waves recombine and interact.

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