Scientists Found the Hidden ‘Edge State’ That May Lead to Practically Infinite Energy

“Hearst Magazines and Yahoo may earn commission or revenue on some items through these links.”

• Studying quantum phenomena—such as the quantum Hall effect and ‘edge state’ electrons—is incredibly difficult because they occur at such small scales.

• Now, scientists at MIT have created an experimental set-up that recreates the quantum Hall effect, but uses ultracold cloud of sodium atoms instead of electrons.

• With interactions occurring over milliseconds (instead of femtoseconds), this experimental stand-in can help scientists further study this fascinating mystery of the quantum world.

One of the hardest things about exploring the quantum world is that many of the phenomena in this “invisible” realm occur at mind-bogglingly small scales.

Take, for example, what is known as the quantum Hall effect. First discovered in 1980 by German physicist Klaus von Klitzing, this effect describes the behavior of electrons (under the influence of a magnetic field and approaching absolute zero temperatures) as they pass through 2D materials, such as graphene. Usually, you’d expect the electrons to experience resistance and scatter, but under these conditions, they formed lossless energy states locked along the material’s boundary.

This quantization of electrical resistance, known as an “edge state,” is particularly useful if you want to create exotic materials free of electrical resistance. But there’s just one problem.

“These states occur over femtoseconds, and across fractions of a nanometer, which is incredibly difficult to capture,” Richard Fletcher, an assistant professor at MIT, said in a press statement. A femtosecond is one quadrillionth of a second. “The beauty is seeing with your own eyes physics which is absolutely incredible but usually hidden away in materials and unable to be viewed directly.”

To actually study this quantum interaction on a more reasonable scale, Fletcher—along with his colleagues at MIT’s Research Laboratory of Electronics and the MIT-Harvard Center for Ultracold Atoms—decided on a novel method to essentially scale up this phenomenon using a cloud of ultracold sodium atoms instead of electrons.

According to the researchers, this allowed the team to watch these edge states form “over milliseconds and microns,” which are much more manageable experimental parameters. The results of the study were published last week in the journal Nature Physics.

To create this quantum interaction on a bigger scale took a large amount of experimental ingenuity. The team used one million ultracold sodium atoms and essentially trapped them in a complex set-up of lasers. However, to simulate the experience of living in a flat space, the researchers also spun them like “riders on an amusement park Gravitron.”

“The trap is trying to pull the atoms inward, but there’s centrifugal force that tries to pull them outward,” Fletcher said. “The two forces balance each other, so if you’re an atom, you think you’re living in a flat space, even though your world is spinning. There’s also a third force, the Coriolis effect, such that if they try to move in a line, they get deflected. So these massive atoms now behave as if they were electrons living in a magnetic field.”

Scientists then defined the “edge” of this gaseous material by introducing a laser, which formed a wall around the atoms. Once atoms encountered this light, they flowed in just one direction—much like electrons at ultra-small quantum scales.

“You can imagine these are like marbles that you’ve spun up really fast in a bowl, and they just keep going around and around the rim of the bowl,” Martin Zwierlein, a co-author of the study, said in a press statement. “There is no friction. There is no slowing down, and no atoms leaking or scattering into the rest of the system. There is just beautiful, coherent flow.”

To test these atoms’ resistances, the team then placed obstacles—such as a point of light—in their paths, and the atoms passed by without any measurable resistance.

Now that scientists have a reliable stand-in for this quantum process, future experiments can push these interactions to the “edge” and begin to explore unknown frontiers of this fascinating piece of quantum physics.

You Might Also Like