A special material — a topological insulator — conducts current only on its surface, as if its interior is a perfect insulator. It hosts a quantum effect similar to the one discovered by Klaus von Klitzing, but mathematically it is equivalent to a four-dimensional world. The problem: the signal is barely discernible — electrical noise drowns it, like a crowd's chatter drowning out a whisper.
The scientists employed negative capacitance — it’s like anti-noise in headphones: a microphone captures the hum, a speaker produces its mirror image, and silence results. Here, an additional circuit cancels out the parasitic capacitance, recovering more than 95% of the signal. Interestingly, this trick has been known to radio engineers for decades, but now it opens a window into the four-dimensional world.
The method promises precise quantum measurements and a chance to discover new physics beyond familiar theories. Axions, ghostly particles, have not yet been caught, but their imprint in the topological insulator is a real lead.
Axions are the leading candidates for dark matter, which makes up about 85% of all matter in the universe, but they have yet to be detected directly.
In 'Interstellar,' the heroes dive into five-dimensional space via a wormhole, while here scientists slip into a four-dimensional world with a clever electrical trick.