A quantum cousin of the Hall effect could open the door to energy-efficient electronics, better sensors, and more-powerful quantum computers. Researchers have now broken a key barrier to its practical application by controlling the phenomenon electrically, rather than magnetically, for the first time.
The Hall effect, discovered by physicist Edwin Herbert Hall in 1879, describes a phenomenon in which applying a perpendicular magnetic field to a conductor creates a voltage that runs sideways across the material. The effect has wide-ranging applications, including sensing and spacecraft propulsion.
In 1980, researchers discovered a quantum version of the Hall effect that occurs in certain materials at very low temperatures. When a strong magnetic field is applied, the interior of the sample becomes an insulator, but an electrical current continues to flow around its edges. Crucially, when this happens, the resistance along the length of the material drops to zero, and the electrons travel around the edges without losing any energy, achieving an effect similar to that of a superconductor.
Finding ways to to exploit these dissipation-less "chiral edge currents," as they are known, could have far-ranging applications in quantum metrology, spintronics, and topological quantum computing. The idea was given a boost by the discovery that thin films of magnetic materials exhibit similar behavior without the need for a strong external magnetic field—something known as the quantum anomalous Hall effect (QAH)—which makes building electronic devices that harness the phenomenon much more practical.
From IEEE Spectrum
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