Researchers have unintentionally made a huge breakthrough in quantum computing by using light to draw and erase microscopic circuits.
A team of scientists from Penn State University and the University of Chicago were working on a simple experiment when they made an astounding discovery. According to a University press release, researchers discovered a new way to draw and erase quantum-mechanical circuits on a new type of material called topological insulators.
The study was authored by Nitin Samarth, a professor of physics at Penn State and David D. Awschalom, the deputy director of the Institute of Molecular Engineering at the University of Chicago. It was published in the October 9 issue of the journal Science Advances by the American Association of the Advancement of Science.
The researchers unintentionally discovered that this new technique of provides more flexibility than nanofibers for writing and editing circuits on topological insulators. Awschalom found the new technique a complete surprise.
The new technique is based on the strange quantum properties of electrons inside of the topological insulators. These electrons, scientists believe, could be useful for the development of spin-based electronics and quantum computing. Using traditional semiconductors has proven ineffective, as the quantum properties of the electrons are lost in the engineering process. The optical effect discovered by the team allows them to “tune” the electrons’ energy levels using different frequencies of light, which allows an unobtrusive manipulation of a particle that was otherwise too fragile.
Scientists can now determine the position of an electron by focusing light in a certain way on it, allowing them to shift around various central pieces of a transistor on the topological insulators. A specific type of fluorescent light being used in the lab was responsible for the shift in data that led the researchers to their discovery.
Determined to find out what exactly was causing this shift in their results, the scientists contacted the developer that installed the lights in the building to find out more information.
They found that strontium titanate, the substrate upon which the researchers had grown their initial samples, could become polarized when it comes in contact with ultraviolet radiation. The wavelength of the lights in the laboratory was just the right length to create an electric field emanating from the polarized strontium titanate. The field leaked onto the topological insulator, which allowed for the discovery.
The circuits drawn by focusing beams of light onto the topological insulators remained even after the light was turned off. By shining bright red light on the circuits, the researchers were able to erase their work and start again from scratch, much like an Etch-a-sketch.
The method worked with other materials including complex oxides, graphene, and transition metal dichalcogenides. The finding could completely rewrite the book on how to approach quantum computing, and the researchers are eager to perform further experiments.