Quantum Mechanics: Scientists May 'Paint' Quantum Electronics with Light Beams

Researchers may be able to "paint" quantum electronics with beams of light. Scientists have found a new way to use light to draw and erase quantum-mechanical circuits in a unique class of materials called topological insulators.

The electrons in topological insulators have unique quantum properties that many scientists believe will be useful for developing spin-based electronics and quantum computers. However, making even the simplest experimental circuits with these materials has proved difficult because traditional semiconductor engineering techniques tend to destroy their fragile quantum properties. In fact, even a brief exposure to air can reduce their quality.

In this latest stud, the researchers examined an optical effect that allows them to "tune" the energy of electrons in these materials using light, without having to touch the material itself. In this case, they used light to draw and erase p-n junctions, which are one of the central components of a transistor.

"To be honest, we were trying to study something completely different," said Andrew Yeats, the lead author of the new study, in a news release. "There was a slow drift in our measurements that we traced to a particular type of fluorescent lights in our lab. At first we were glad to be rid of it, and then it struck us-our room lights were doing something that people work very hard to do in these materials."

The researchers found that the surface of strontium titanate, the substrate material on which they grew their samples, becomes electrically polarized when exposed to ultraviolet light, and their room lights happened to emit at just the right wavelength. The electric field from the polarized strontium titanate was leaking into the topological insulator level and changing its electronic properties.

The researchers then conducted a number of control measurements to show that the optical effect is not unique to topological insulators, and can act on other materials grown on strontium titanate.

The findings could be huge for better understanding a wide range of nanoscale materials, and could allow electrical tuning of materials in a wide range of optical, magnetic or spectroscopic experiments.

The findings are published in the journal Science Advances.

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