In what can only be described as a happy accident, scientists at the University of Chicago and Penn State University have discovered a way to “paint” quantum circuits on a topological insulator grown on a particular substrate using a specific frequency of ultraviolet light. This new breakthrough enables scientists to draw – and erase – circuits on the topological insulators noninvasively, which makes working with the volatile material much simpler than ever before.
An amazing article on the Science Daily website reveals the details:
“This observation came as a complete surprise,” said David D. Awschalom, Liew Family Professor and deputy director in the Institute of Molecular Engineering at UChicago, and one of two lead researchers on the project. “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 article continues:
“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 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 at just the right wavelength. The electric field from the polarized strontium titanate was leaking into the topological insulator layer, changing its electronic properties.
Awschalom and his colleagues found that by intentionally focusing beams of light on their samples, they could draw electronic structures that persisted long after the light was removed.
“It’s like having a sort of quantum etch-a-sketch in our lab,” he said. 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 cleanroom and potentially contaminating our materials,” said Awschalom, “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.”
Interestingly, the effect is not limited to topological insulators, but extends to other materials that are grown on the same substrate:
“In a way, the most exciting aspect of this work is that it should be applicable to a wide range of nanoscale materials such as complex oxides, graphene, and transition metal dichalcogenides,” said Awschalom
We’re looking forward to what this accidental breakthrough in quantum computing will enable. In the meantime, you can learn more about it via Science Daily’s excellent article.
Source: ScienceDaily.com – “Scientists paint quantum electronics with beams of light“
Featured Image Source: Peter Allen