Superconductivity Breakthrough: Frictionless Flow of Edge State Atoms
Sampson Wilcox
MIT scientists have successfully guided atoms into a unique “edge state” for the first time, enabling them to move without any friction. This breakthrough could pave the way for improved superconductor materials.
When electrons pass through various materials, they experience varying degrees of resistance. Insulators block most movement, semiconductors permit some, conductors allow a significant amount, and superconductors enable complete movement without resistance. Superconductors could therefore be ideal for rapid data and energy transmission, and their powerful electromagnetic fields could facilitate levitating high-speed transportation.
The challenge with studying electron movement is that these particles are incredibly small and move at high speeds, making them difficult to observe. To address this, the MIT team found a way to replicate this behavior using atoms, which are larger and slower.
Superconductivity at the Boundaries
The researchers focused on a form of superconductivity known as edge states. In certain materials, electrons don’t flow freely throughout but are restricted to the edges, where they move frictionlessly. Even when encountering obstacles, they glide around them seamlessly instead of bouncing off as they typically would.
For electrons, these edge states occur over femtoseconds (quadrillionths of a second) and span distances of mere fractions of a nanometer, making them difficult to observe. Atoms, however, make this behavior much easier to see.
“In our setup, the same physics happens with atoms, but on the scale of milliseconds and microns,” explained Martin Zwierlein, co-author of the study. “This allows us to capture images and watch the atoms slowly move along the system’s edge for extended periods.”
The team trapped about a million sodium atoms in a laser at temperatures just above absolute zero, rapidly spinning them in circles.
Atoms Behave Like Electrons in a Magnetic Field
“The trap pulls the atoms inward, while centrifugal force pulls them outward,” explained Richard Fletcher, co-author of the study. “These forces balance each other, so the atoms behave as if they’re in a flat space, even though their world is spinning. A third force, the Coriolis effect, deflects them when they try to move in a straight line, making these heavy atoms behave like electrons in a magnetic field.”
The team then introduced an edge—a ring of laser light that formed a boundary. When the atoms touched the ring, they adhered to it, moving freely along the edge in one direction.
To test their behavior further, the researchers added obstacles by shining points of light into the ring. Despite the interference, the atoms flowed around the obstacles effortlessly.
“We deliberately placed a large, repelling green light, and the atoms should have bounced off it,” said Fletcher. “But instead, they smoothly navigated around it, returned to the edge, and continued moving.”
This atom behavior closely mirrors how electrons move in edge states, making it visible for the first time. Scientists can now use this model to explore new theories, potentially improving superconductor materials.
“It’s a clear realization of elegant physics, and we can directly demonstrate the importance of the edge,” Fletcher added. “The next step is to add more obstacles and interactions to the system, where the outcomes become less predictable.”
Read the original article on: New Atlas
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