A group of scientists from different countries found out that a remarkable type of structure, made up of thin sheets of two-dimensional materials, could help make quantum computing more accessible.
A group of researchers from Penn State Center for Nanoscale Science just released a study in the Nature Materials journal. The team is part of 19 centers in the U.S that are supported by National Science Foundation and is called Materials Research Science and Engineering Centers (MRSEC).
Regular computers use tiny parts called transistors, and these parts are usually turned on (1) or off (0). Quantum computers use something different – quantum bits, or qubits. Qubits can be both a 1 and 0 at the same time which makes them much more powerful than regular computer parts. But there are challenges that must be solved in order to make a quantum computer work properly.
Companies like IBM and Google are working to create quantum computers that use ‘superconducting qubits’. Unfortunately, these computers can make mistakes because of the environment around them. Professor Jun Zhu from Penn State says that a potential solution for this issue could be found in a special type of qubit called a ‘topological qubit’.
Scientists think that using topological superconductors for making qubits will make them protected from bad things in their environment. This is because the superconductivity has a special property called “topology” which helps keep the qubits safe.
A topological qubit is a special kind of qubit that exists only in theory. It has something to do with the way certain materials can bend, stretch or change but keep their original traits at the same time. This type of qubit could help protect quantum processes from being messed up by outside influences.
Cequn Li, a physics graduate student who wrote the study, is interested in something called topological quantum computing. He said that this kind of quantum computing could help us build computers with fewer errors. The key to making this work is to find the right materials for it.
Researchers have created a special type of material called a heterostructure. It has two layers: one layer is a topological insulator made from bismuth antimony telluride (Bi,Sb)2Te3 and the other is a superconducting gallium layer.
Researchers have figured out a new way to check if superconductivity can happen in a material called (Bi,Sb)2Te3 film. Superconductivity can help us create topological materials and that’s why it’s very important. The research showed that this type of superconductivity happens on the surface of (Bi,Sb)2Te3 film. Even though the results are good, it might be difficult to actually create topological insulator/superconductor structures from this kind of material.
Li explained that it can be hard to join materials because they have different structures and they might react with each other, resulting in a complicated interface.
The scientists are trying a technique called confinement heteroepitaxy. It works by inserting a thin sheet of carbon atoms in between the gallium layer and then the (Bi, Sb)2Te3 layer. It’s similar to how two pieces of Lego fit together – it joins them together to become one.
“Graphene works like a kind of protective wall,” according to Li. He explains that it stops two different materials from reacting with each other, allowing them to be connected together nicely.
Plus, the researchers proved how this method can be applied at a very large scale, which means that it could be used in quantum computing. To accomplish this, they use things called wafers – thin slices of semiconductor material that are used as the foundation for electronic equipment.
Li said that the heterostructure we have, contains all the parts for making a topological superconductor. It could be made as a thin film and is potential to become much bigger. That way, if it’s successful, it could be used to develop a topological quantum computer in the future.
A team of researchers from Penn State University, led by Zhu and Joshua Robinson, have done some research together. They were helped by Prof. Cui-Zu Chang, Prof. Henry W. Knerr and Assistant Professor Danielle Reifsnyder Hickey in the project as well.
“The members of our MRSEC’s IRG1 team achieved something special,” said Zhu. “Robinson’s group grown two layers of gallium film using something called confinement heteroepitaxy. Chang’s group grew the topological insulator film with help from the molecular beam epitaxy. Finally, Reifsnyder Hickey and staff at the Materials Research Institute examined these structures and devices on an atomic scale.”
The next step is to make the process even better and take us one step closer to building a topological quantum computer. To do this, our collaborators are trying to improve the materials that make it up by making them more uniform and of higher quality. Our team is also working on building more advanced devices on these heterostructures so that we can detect the signs of topological superconductivity.
An exciting new article was published recently in Nature Materials called “Proximity-induced superconductivity in epitaxial topological insulator/graphene/gallium heterostructures”. It’s written by 13 authors including Cequn Li and Jun Zhu. In the article, they explain how they were able to use certain materials to successfully create a superconducting material that can transfer energy quickly and efficiently. This could revolutionize future energy transmission!
