“To be honest, we were trying to study something completely different,” said Andrew Yeats, a graduate student in Professor David Awschalom’s laboratory at the University of Chicago. “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.”
The ‘accident’ outlined a way of using light to draw and erase quantum-mechanical circuits on topological insulators. The technique is said to be beter than approaches based on chemical processing because it allows for rewritable ‘optical fabrication’.
Topological insulators are attractive for use in spin based electronics and quantum computers. However, even simple circuits have proved difficult to make because traditional approaches destroyed the quantum properties. The optical approach allows electron energy to be ‘tuned’ without having to touch the material itself. The team has used this effect to draw and erase a P-N junction.
By focusing beams of light on their samples, the researchers could draw electronic structures that persisted long after the light was removed. They also found that bright red light counteracted the effect of the ultraviolet light, allowing circuits to be written and erased.
