Physicists have made a remarkable breakthrough by directly observing the phenomenon of ‘edge states’ in a cloud of ultracold atoms. This rare and remarkable behavior, where particles flow without resistance even in the presence of obstacles, could lead to revolutionary advancements in energy and data transmission.
Defying the Laws of Friction
As in the case of colliding billiard balls however, particles will normally experience friction and scatter randomly on encountering an obstacle. Instead, in some exotic materials, particles do something remarkable.
Rather than bouncing off in all directions, these particles could “get stuck” at the material edge and move in an orderly single file fashion oriented along side of a draped blanket like marching ants. It sets up what is known as an ‘edge state’, enabling the particles to move without resistance, skimming freely past obstructions while adhering to their edge-dwelling route.
In a superconductor all particles in a material flow without resistance, whereas the current carried by these edge modes flows only at its boundary. For the first time, MIT physicists have observed a novel state of matter, one that superconducts so easily that it resists forming little whirlpools of supercurrent in response to tiny magnetic fields induced at its edges.
A Leap from Electrons to Atoms
The original motivation to search for edge states comes from the Quantum Hall effect, a striking phenomenon found that in experiments with layered material when electrons can move only along two dimensions of motion and not other. Edge state has been first proposed by physicists to understand the underlying physics. In these experiments, the electrons did not travel through the bud in a straight line but instead crowded one end by quanta.
When the MIT team wanted to study this phenomenon, they then demonstrated that it was possible to reproduce the same physics in a larger and more observable system using ultra-cold atoms. They surrounded a cloud of roughly 1 million sodium atoms in a laser-cooled trap and cooled it to nanokelvin temperatures, thus effectively reducing the element − coupled vibrational excitations of impurity pairs − to keep up with electrons in magnetic field.
To create this diverse world, the researchers placed a ‘wall’ of laser light around the spinning atoms in the shape of a ring. As they imaged the system, they saw that as atomic flow moved in one direction along their edge state, it did so perfectly — with no skips or bumps or sound of friction — even when barriers were put in its path. It is the same behavior that made many people predict that electrons would exhibit such an effortless flow, only it is now documented in atoms.
Conclusion
The findings of the MIT physicists are groundbreaking because they show the extraordinary edge states, which enable particles to move entirely unimpeded even if obstacles exist. The discovery, thanks to observations of ultracold atoms, could be the answer for groundbreaking super-efficient, lossless energy and data transmission. This manipulation of the flow of electrons in ‘edge states’ could signal a new way to disrupt everything from electronics to renewable energy.
