NEW DELHI: A team of scientists has accidentally discovered a unique property that may lead to great progress in developing advanced computers and quantum microchips . While working with a special material, the scientists found that switching on the laboratory lights created certain designs on the material that would otherwise require intensive time-consuming work and equipment.

The team of scientists from Penn State University and the University of Chicago discovered that beams of light could be used to draw and erase quantum-mechanical circuits on topological insulators, a unique class of materials in which the interior is an insulator while the surface can conduct electricity.

The research, led by Nitin Samarth of Penn State and David D. Awschalom of the University of Chicago, is published in Science Advances, the new online journal of the American Association for the Advancement of Science, where it is featured on the journal's front page.

"This observation came as a complete surprise," Awschalom said. "It's one of those rare moments in experimental science where a seemingly random event - turning on the room lights - generated unexpected effects with potentially important impacts in science and technology."

The new technique is more flexible than advanced nanofabrication facilities based on chemical processing because it allows for rewritable "optical fabrication" of the topological insulators.

"To be honest, we were trying to study something completely different," said Andrew Yeats, a graduate student in Awschalom's laboratory and the paper's lead author. "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 went back to Bulley & Andrews, the contractor that renovated the lab space for more information about the lights. "I've never had a client so obsessed with the overhead lighting," said Frank Floss, superintendent for Bulley & Andrews Construction. "I could have never imagined how important it would turn out to be."

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

They also found that bright red light counteracted the effect of the ultraviolet light, allowing them to both write and erase. "Instead of spending weeks in the clean room and potentially contaminating our materials," Awschalom said, "now we can sketch and measure devices for our experiments in real time. When we're done, we just erase it and make something else. We can do this in less than a second."

At Penn State, Samarth said "One exciting aspect of this work is that it's noninvasive. Since the electrical polarization occurs in an adjacent material, and the effect persists in the dark, the topological insulator remains relatively undisturbed." Samarth added, "With these fragile quantum materials, sometimes you have to use a light touch."