Over the past several years, some materials have proved to be a playground for physicists. These materials aren’t made of anything special — just normal particles such as protons, neutrons and electrons. But they are more than the sum of their parts. These materials boast a range of remarkable properties and phenomena and have even led physicists to new phases of matter — beyond the solid, gas and liquid phases we’re most familiar with.
One class of material that especially excites physicists is the topological insulator — and, more broadly, topological phases, whose theoretical foundations earned their discoverers a Nobel Prize in 2016. On the surface of a topological insulator, electrons flow smoothly, while on the inside, electrons are immobile. Its surface is thus a metal-like conductor, yet its interior is a ceramic-like insulator. Topological insulators have drawn attention for their unusual physics as well as for their potential use in quantum computers and so-called spintronic devices, which utilize electrons’ spins as well as their charge.
But such exotic behaviors aren’t always obvious. “You can’t just tell easily by looking at the material in conventional ways whether it has these kinds of properties,” said Frank Wilczek, a physicist at the Massachusetts Institute of Technology and winner of the 2004 Nobel Prize in Physics.
This means a host of seemingly ordinary materials might harbor hidden — yet unusual and possibly useful — properties. In a paper recently posted online, Wilczek and Qing-Dong Jiang, a physicist at Stockholm University, propose a new way to discover such properties: by probing a thin aura that surrounds the material, something they’ve dubbed a quantum atmosphere.
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