Researchers at the Massachusetts Institute of Technology (MIT) have observed and captured images of a rare “edge state” in ultracold atoms. Using these findings, they can learn to achieve and harness the edge states of electrons in different materials. This breakthrough in the field of quantum physics could lead to the discovery of practically infinite energy sources.
The “edge state” of electrons is a special situation where electrons move along the boundaries or edges of certain materials, rather than through the middle.
“In this rare ‘edge state,’ electrons can flow without friction, gliding effortlessly around obstacles as they stick to their perimeter-focused flow,” the study authors note.
Such frictionless movement of electrons can enable data and energy transfer across devices without any transmission losses, leading to the development of super-efficient electronic circuits and quantum computers.
Capturing the edge state in electrons is not easy
In 1980, a German physicist named Klaus von Klitzing proposed that in certain 2D materials at very low temperatures and under strong magnetic fields, electric current flows along the edges in a quantized manner. This phenomenon is called the quantum hall effect .
It is closely related to the edge state of electrons because, in materials showing the quantum hall effect, electrons in the interior are locked and are unable to conduct electricity. However, they start moving in a straight line across the edges of the material, forming an edge state.
In the “edge state,” the electrons are not scattered and continue to move across the boundary of the material even if there is an obstacle in their path. This smooth and stable flow of electrons in edge states gives rise to the hall currents responsible for the quantum hall effect.
However, it is almost impossible for scientists to observe the edge state of electrons because it occurs in a fraction of time.
“To actually see them is quite a special thing because these states occur over femtoseconds, and across fractions of a nanometer, which is incredibly difficult to capture,” Richard Fletcher, one of the study authors and an assistant professor of physics at MIT, said .
So, does that mean there’s no way to observe and harness the power of the edge states? Well, the researchers were clever enough to come up with an interesting solution to this problem.
Instead of trying to catch the edge states of electrons, they focused on atoms and performed an experiment that allowed them to observe the “edge state” on a bigger scale.
How can atoms show similar behavior
The study authors thought that if electrons in some materials can enter the edge state, possibly atoms might also be able to do the same. So, they decided to observe atoms under similar conditions that trigger the edge state in electrons.
They trapped one million sodium atoms using controlled lasers and cooled them down to nearly absolute zero temperature. Next, they made the laser trap spin the atoms around, similar to how people spin in a Gravitron ride.
“The trap is trying to pull the atoms inward, but there’s centrifugal force that tries to pull them outward. 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,” Fletcher explained.
“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.”
The researchers then used another ring-shaped laser light to form a circular edge around the spinning atoms. Surprisingly, the atoms started flowing along the edge in a line, demonstrating edge states similar to what is believed to exist in the case of electrons.
“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,” Martin Zwierlein, one of the researchers and a physics professor at MIT, said. The researchers also introduced some obstacles but they couldn’t slow down or disturb the movement of the atoms.
They were able to observe this edge state of atoms for a few milliseconds and also captured images. In future experiments, they plan to test this edge state against more obstacles.
Hopefully, these results will contribute to the development of super-efficient data and energy transfer techniques in the future.
The study is published in the journal Nature Physics .
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