Under the right conditions, electrons can be freed from rapid hopping and high-pressure traffic deep within the conductor by bypassing its boundaries. There, they can convert easy circuits into unidirectional, resistance-free current.
While the theory describes the basic principles behind the flow of electrons in an “edge state,” understanding it well enough to develop applications that might exploit its benefits has proven difficult thanks to its small, transient behavior.
In a new study, researchers from the Massachusetts Institute of Technology (MIT) used a cloud of ultracold sodium atoms to replace electrons — achieving the same effect as edge state physics, but on a scale and duration sufficient to allow them to study it in detail.
“In our setup, the same physics happens in atoms, but on the scale of milliseconds and microns.” He says Physicist Martin Zuerlein.
“This means we can take pictures and watch atoms basically crawl forever along the edge of the system.”
According to what is known as the Hall effect, voltages arise when a magnetic field is positioned perpendicular to the current. there Quantum version This also has the effect, since in flat two-dimensional space, electrons move in circles relative to the surrounding fields.
When this two-dimensional surface is the edge of a piece of a class of “topological” materials, the electrons should accumulate at specific locations and move in a quantum manner as predicted by quantum physics. Although this phenomenon is common, relating material properties to flow speed and direction is not easy. These actions last only a femtosecond (a quadrillionth of a second), making them practically impossible to study properly.
Instead of studying electrons, this latest research involved about a million sodium atoms, which were moved into place using a laser and reduced to an extremely cold state. The entire system was then manipulated to make the atoms orbit the laser trap.
This rotation, in addition to other physical forces acting on the atom, mimics one of the basic conditions of the edge state: magnetic field. A ring of laser light was then inserted to act as the edge of the material.
When atoms collide with the ring of light, they move in a straight line and in one direction along it, as happens with electrons in the edge state. Even the obstacles provided by the researchers were unable to deflect the atoms.
“You can imagine it’s like marbles that you spin very quickly in a bowl, and they keep spinning around the edge of the bowl.” He says Zwerlin.
“There’s no friction. There’s no hysteresis, and the atoms don’t leak or spread out into the rest of the system. There’s just a beautiful, coherent flow.”
The researchers were able to observe interactions in their system that matched previous theoretical predictions of edge states, suggesting that these atoms could indeed replace electrons in this type of study — although this is the first time this has ever been done. This is still the case. The first days.
Phenomena such as the Quantum Hall effect are closely related to superconductivity, the idea of transmitting electrical energy more efficiently, with no heat loss. These results can also aid research Quantum computers And advanced sensors.
“It’s a very clear realization of a very beautiful piece of physics, and we can demonstrate first-hand the importance and reality of this edge.” He says Physicist Richard Fletcher, from the Massachusetts Institute of Technology.
“The natural trend now is to introduce more obstacles and interactions into the system, as things become clearer about what to expect.”
The research was published in Nature physics.
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