Particle physics research

New quantum research experiments with an exotic state of matter

Inside NASA’s Cold Atom Lab, scientists form bubbles from ultracold gas, shown in pink in this illustration. Lasers, also pictured, are used to cool the atoms, while an atomic chip, shown in gray, generates magnetic fields to manipulate their shape, in combination with radio waves. Credit: NASA/JPL-Caltech

product inside[{” attribute=””>NASA’s Cold Atom Lab, the ultracold bubbles provide new opportunities to experiment with an exotic state of matter.

Since the days of NASA’s Apollo program, astronauts have documented (and contended with) how liquids like water behave differently in microgravity (see video below) than they do on Earth – coalescing into floating spheres instead of bottom-heavy droplets. Now, researchers have demonstrated this effect with a much more exotic material: gas cooled to nearly absolute zero (minus 459 degrees Fahrenheit, or minus 273 degrees Celsius), the lowest temperature matter can reach.

Water in space behaves… differently. Surface tension and capillary flow can be exploited to move fluids more efficiently. What sounds like fun might actually help us improve systems for moving fluids in microgravity, in things like fuel tanks for space travel. Credit: NASA Johnson Space Center

Using NASA’s Cold Atom Lab, the first-ever quantum physics facility aboard the International Space Station (ISS), researchers took samples of atoms cooled to less than a millionth of a degree above above absolute zero and shaped them into extremely thin, hollow spheres. The cold gas starts out in a small round blob, like an egg yolk, and is sculpted into something more like a thin eggshell. On Earth, similar attempts fail: atoms cluster downward, forming something more like a contact lens than a bubble.

The milestone – described in a new research paper published Wednesday, May 18, 2022 in the journal Nature – is only possible in the microgravity environment of the space station.

Clouds of ultracold atoms are manipulated into hollow spheres inside NASA’s Cold Atom Lab aboard the International Space Station. In this series of images, clouds are seen at different stages of inflation, capturing the appearance of a single cloud of atoms when manipulated into a bubble. Credit: NASA/JPL-Caltech

Ultracold bubbles could eventually be used in new kinds of experiments with an even more exotic material: a fifth state of matter (distinct from gases, liquids, solids, and plasmas) called the Bose-Einstein condensate ( BEC). In a BEC, scientists can observe the quantum properties of atoms on a scale visible to the naked eye. For example, atoms and particles sometimes behave like solid objects and sometimes like waves – a quantum property called “wave-particle duality”.

The job requires no astronaut assistance. The ultra-cold bubbles are made inside Cold Atom Lab’s hermetically sealed vacuum chamber using magnetic fields to gently manipulate the gas into different shapes. And the lab itself — which is about the size of a mini-fridge — is operated remotely from JPL.

The largest bubbles are about 1 millimeter in diameter and 1 micron thick (i.e. one thousandth of a millimeter or 0.00004 inches). They are so fine and diluted that only thousands of atoms compose them. By comparison, one cubic millimeter of air on Earth contains about one billion billion molecules.

“These aren’t like your average soap bubbles,” said David Aveline, lead author of the new work and a Cold Atom Lab science team member at NASA’s Jet Propulsion Laboratory in Southern California. “Nothing we know of in nature gets as cold as the atomic gases produced in Cold Atom Lab. So we start with this very unique gas and study how it behaves when shaped into fundamentally different geometries. And, historically, when a material is manipulated in this way, very interesting physics can emerge, along with new applications.

Why is it important’

Exposing materials to different physical conditions is key to understanding them. It is also often the first step to finding practical applications for these materials.

Conducting these types of experiments on the space station using the Cold Atom Lab allows scientists to suppress the effects of gravity, which is often the dominant force impacting the movement and behavior of fluids. By doing so, scientists can better understand the other factors involved, such as the surface tension or viscosity of a liquid.

Now that the scientists have created the ultracold bubbles, their next step will be to turn the ultracold gas that makes up the bubbles into the BEC state and see how it behaves.

“Some theoretical work suggests that if we work with one of these bubbles that is in the BEC state, we might be able to form vortices – basically, small vortices – in quantum material,” Nathan said. Lundblad, professor of physics at Bates. College of Lewiston, Maine, and principal investigator of the new study. “It’s an example of a physical configuration that could help us better understand the properties of the BEC and better understand the nature of quantum matter.”

The field of quantum science has led to the development of modern technologies such as transistors and lasers. Quantum investigations performed in Earth orbit could lead to improvements in spacecraft navigation systems and sensors to study Earth and other solar system bodies. Ultracold atom facilities have been operating on Earth for decades; however, in space, researchers can study ultracold atoms and BECs in new ways because the effects of gravity are reduced. This allows researchers to regularly reach colder temperatures and observe phenomena for longer than they can on Earth.

“Our main focus with Cold Atom Lab is basic research – we want to use the space station’s unique space environment to explore the quantum nature of matter,” said Jason Williams, Cold Atom Lab project scientist at JPL. “The study of ultracold atoms in new geometries is a perfect example.”

Reference: “Observation of ultracold atomic bubbles in orbital microgravity” by RA Carollo, DC Aveline, B. Rhyno, S. Vishveshwara, C. Lannert, JD Murphree, ER Elliott, JR Williams, RJ Thompson and N. Lundblad, May 18, 2022 , Nature.
DOI: 10.1038/s41586-022-04639-8

Learn more about the mission

Designed and built at JPL, Cold Atom Lab is sponsored by the Biological and Physical Sciences (BPS) Division of NASA’s Science Mission Directorate at agency headquarters in Washington. BPS is at the forefront of scientific discovery and enables exploration using space environments to conduct investigations not possible on Earth. Studying biological and physical phenomena under extreme conditions allows researchers to advance the fundamental scientific knowledge needed to go further and stay longer in space, while benefiting life on Earth.