Physicists to do super-cool research in space
WSU physicist Peter Engels’s new research is literally out of this world.
Engels studies the behavior of atoms laser-cooled to temperatures just a few billionths of a degree above absolute zero, the point where clouds of atoms behave like one wave instead of discrete particles. But the unavoidable presence of gravity on our planet makes it difficult to clearly observe this super-cooled substance—called a Bose-Einstein condensate (BEC)—and the laws of quantum physics that govern its wave-like behavior.
To overcome these Earthly limitations, Engels and graduate student researcher Maren Mossman are moving their work to outer space.
Next August, they will join a team of scientists using a remotely operated laser-cooling device, called the Cold Atom Laboratory (CAL), which NASA will send to the International Space Station (ISS) aboard a SpaceX rocket.
Unlocking new potential
Engels and Mossman will use CAL and the space station’s microgravity environment to create and study BECs for up to 10 seconds at a time, unlocking the potential to observe new quantum phenomena never before seen on Earth.
Their research will be the start of a new chapter in the study of quantum physics that could eventually help in the development of ultra-powerful quantum computers and a wide variety of advanced sensors for measuring such things as gravity, rotations, and magnetic fields.
“While CAL is first and foremost a fundamental science experiment, there are many different directions in which the knowledge we will gain could be applied,” Engels said.
“Cold atom research on the ISS will give us a fundamental understanding for a part of physics that is so complicated that, even with the most powerful computers on Earth, we cannot find answers. Our work will, in turn, provide new insights into systems that may be important in the design of future materials and electronics like ultra-precise gravitational sensors to detect caves underground or hidden oil fields. The options are really quite limitless and exciting.”
Strange world of quantum physics
Normally, atoms can be imagined like billiards balls bouncing around a pool table. However, when they are super-cooled to form a BEC or when only two or three of them are isolated together, atoms and subatomic particles, like electrons, stop behaving like individual balls and start behaving like an ocean wave. This synchronized and wave-like behavior is the basis of what is known as quantum physics.
As computer chips and electronics get into regimes where the circuitry is so small it can’t be viewed with a conventional microscope, the effects of quantum physics have to be taken into account. The problem scientists will run into when trying to engineer such devices is they currently have only limited or indirect tools to study the behavior of matter at such a small scale.
“Even with our most powerful optical imaging technology, we cannot observe how two or three atoms interact,” Mossman said. “So instead, what we will be doing with CAL is studying a much larger group of super-cooled atoms that behave in the same way and can be observed on the ISS with an optical microscope. We can then transfer what we learn about this quantum mechanical weirdness to determining how a small number of atoms interact.”
Countdown to launch
For the last three years, Engels and Mossman have been working closely with colleagues at NASA’s Jet Propulsion Laboratory (JPL) in California to make sure that their planned experiments with CAL will work flawlessly once the instrument is in outer space. The two WSU scientists are part of one of five research groups that have been running preliminary tests and computer simulations on a ground-based version of CAL in preparation for next year’s launch.
“We are accustomed to being able to pull something out and fixing it if it breaks, which, of course, won’t be possible in space. Everything will be remotely controlled,” Mossman said. “The astronauts onboard the ISS don’t have the expertise to run these kinds of experiments so we are very fortunate JPL is so good at engineering things.”
On the ISS, CAL will use a complex array of lasers, magnetic traps, and vacuum chambers to cool clouds of rubidium and potassium atoms to temperatures colder than any naturally occurring place in the universe several hundred times a day.
The data will then be beamed down to Earth where Engels, Mossman, and their collaborators will interpret it.