The remotely operated facility aboard the International Space Station has created another tool that researchers can use to probe the fundamental nature of the world around us.
For the first time in space, scientists have produced a quantum gas containing two types of atoms. Made with NASA Cold Atom Laboratory aboard the International Space Station, the achievement marks another step toward bringing quantum technologies currently available only on Earth to space.
Quantum tools are already used in everything from mobile phones to GPS and medical devices. In the future, they could be used to improve the study of planets, including our own, and help solve the mysteries of the universe while deepening our understanding of the fundamental laws of nature.
He new jobconducted remotely by scientists on Earth, is described in the Nov. 16 issue of the journal Nature.
With this new capability, the Cold Atom Lab can now study not only the quantum properties of individual atoms, but also quantum chemistry, which focuses on how different types of atoms interact and combine with each other in a quantum state. Researchers will be able to conduct a broader range of experiments with Cold Atom Lab and learn more about the nuances of conducting them in microgravity. That knowledge will be essential to harnessing the one-of-a-kind facility to develop new space-based quantum technologies.
The physical world around us depends on atoms and molecules staying together according to a set of established rules. But different rules can dominate or weaken depending on the environment the atoms and molecules are in, such as microgravity. Scientists using the Cold Atom Lab are exploring scenarios in which the quantum nature of atoms dominates their behaviors. For example, instead of acting like solid billiard balls, atoms and molecules behave more like waves.
In one such scenario, atoms in two- or three-atom molecules may stay together but move further apart, almost as if the molecules are becoming spongy. To study these states, scientists first need to slow down the atoms. They do this by cooling them to fractions of a degree above the The lowest temperature that matter can reach.much colder than anything found in the natural universe: absolute zero, or minus 459 degrees Fahrenheit (minus 273 degrees Celsius).
Physicists have created these spongy molecules in experiments with cold atoms on Earth, but they are extremely fragile and quickly break down or collapse back to a normal molecular state. For this reason, molecules enlarged with three atoms have never been directly imaged. In the space station’s microgravity, fragile molecules can exist longer and potentially get larger, so physicists are excited to start experimenting with the Cold Atom Lab’s new capability.
These types of molecules are not likely to be found in nature, but it is possible that they could be used to make sensitive detectors that can reveal subtle changes in the strength of a magnetic field, for example, or any of the other perturbations that cause they break. separate or collapse.
“What we’re doing with cold atom science in general is looking and learning about new tools that nature gives us,” said Jason Williams of NASA’s Jet Propulsion Laboratory in Southern California, project scientist for the Cold Atom Laboratory and co-author. about the new study. “It’s like we discovered a hammer and were starting to investigate all the ways we could use it.”
A modern mystery
One possible way to use a quantum gas with two types of atoms would be to test something called the equivalence principle, which holds that gravity affects all objects in the same way regardless of their mass. It’s a principle that many physics teachers will demonstrate by placing a pen and a hammer in a sealed vacuum chamber and showing that, in the absence of air friction, the two fall at the same rate. In 1971, Apollo 15 astronaut David Scott performed this experiment on the surface of the Moon without the need for a vacuum chamber.
Using an instrument called an atomic interferometer, scientists have already conducted experiments on Earth to see if the equivalence principle holds at atomic scales. Using a quantum gas with two types of atoms and an interferometer in the space station’s microgravity, they were able to test the principle with greater precision than is possible on Earth. By doing so, they could discover whether there is a point at which gravity does not treat all matter equally, indicating that Albert Einstein’s general theory of relativity contains a small error that could have big implications.
The equivalence principle is part of the general theory of relativity, the backbone of modern gravitational physics, which describes how large objects, such as planets and galaxies, behave. But a major mystery in modern physics is why the laws of gravity do not seem to coincide with the laws of quantum physics, which describe the behavior of small objects, such as atoms. The laws of both fields have been proven correct time and time again at their respective sizes, but physicists have not been able to unite them into a single description of the universe as a whole.
Looking for features of gravity that Einstein’s theory does not explain is one way to search for a means of unification.
Scientists already have ideas to go beyond testing fundamental physics in microgravity within the Cold Atom Lab. They have also proposed space experiments that could use a two-atom interferometer and quantum gases to measure gravity with high precision in order to learn about the nature of dark energy, the mysterious driver behind the accelerated expansion of the universe. What they learn could lead to the development of precision sensors for a wide range of applications.
The quality of those sensors will depend on how well scientists understand the behavior of these atoms in microgravity, including how those atoms interact with each other. Introducing tools to control atoms, such as magnetic fields, can cause them to repel each other like oil and water or stick together like honey. Understanding those interactions is a key goal of the Cold Atom Lab.
More about the mission
JPL, a division of Caltech in Pasadena, designed and built Cold Atom Lab, sponsored by Biological and Physical Sciences (BPS) of NASA’s Science Mission Directorate at the agency’s headquarters in Washington. BPS pioneers scientific discoveries and enables exploration using space environments to conduct research not possible on Earth. The study of biological and physical phenomena under extreme conditions allows researchers to advance the fundamental scientific knowledge necessary to go further and stay longer in space, while benefiting life on Earth.
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Jet Propulsion Laboratory, Pasadena, California.