The simulation shows that there are vacancies in Silicon carbide. The red shows void volumes. Left: qubit. The divacancy formation is in the crystal lattice. Simulation results with combined codes. The University of Chicago.
"Vacancy" is a sign you want to look for when searching for a hotel room on a road trip. You want to see vacancies when it comes to quantum materials. Scientists remove atoms in materials. The basic unit of quantum technology can be served by such vacancies.
Researchers at the DOE's Argonne National Laboratory and the University of Chicago have made a breakthrough that should help pave the way for improved control over the formation of vacancies.
Semiconductors are used in cell phones, computers, medical equipment and more. The existence of atomic-scale defects in the form of vacancies is undesirable for those applications. Recent studies show that certain types of vacancies in Silicon Carbide and other Semiconductors show promise for the realization of qubits in quantum devices. Unhackable communication networks and hypersensitive sensors can be used in applications of qubits. New types of computers that can solve complex problems beyond the reach of classical computers are possible in the future.
Giulia Galli, a professor of chemistry at the University of Chicago, said that scientists already know how to make qubit-worthy vacancies in semiconductors. "But for practical new quantum applications, they still need to know more about how to personalize vacancies with desired features."
There are single vacancies in the crystal lattice when individual Silicon and carbon atoms are removed. There is a carbon and an adjacent Silicon vacancies. The divacancy is a key candidate as a qubit. The yield for converting single vacancies into divacancies has been low. Scientists are trying to increase that yield.
"To create actual defects in a sample, you shoot a beam of high-velocity electrons at it, and this knocks out individual atoms," said Elizabeth Lee, a researcher in the UChicago Pritzker School of Molecular Engineering. unwanted defects are created by that electron bombardment.
Scientists can heal those defects by treating the sample at very high temperatures and cooling it down again to room temperature. The trick is to create a process that will keep the wanted defects and heal the unwanted ones.
"We can watch defects forming, moving, disappearing and rotating in a sample over time at different temperatures by performing computer simulations at the atomic scale with high- performance computers," said Lee. This is something that can't be done on a trial basis.
divacancy is changing its orientation in the video. The University of Chicago.
The team's simulations tracked the pairs of individual vacancies into a divacancy. The discoveries they made should pave the way for new quantum devices. The more vacancies there are relative to the carbon vacancies at the start of heat treatment, the more divacancies afterwards. The determination of the best temperatures for creating stable divacancies and for altering their orientation within the crystal structure without destroying them are two other things.
Scientists may be able to align the divacancies in the same direction. It would be ideal for applications that can operate with many times the resolution of today's sensors.
"Divacancies can convert into an entirely new type of defect, which is a totally unexpected and exciting finding," said Lee. Scientists call the defects an anti-site because they consist of two carbon vacancies. A carbon atom has filled the open space left by the removal of a Silicon atom.
The team's simulations were the first of their kind and were made possible by the development of new simulation algorithms and the use of computer codes developed by the Midwest Integrated Center for Computational Materials. The new algorithms were developed by a senior scientist in the Materials Science Division and UChicago professor of molecular engineering.
The formation and motion of vacancies or defects in Semiconductors are what we call rare events. It's not possible to study such events on the fastest computer on the planet. We need to develop new ways of promoting the occurrence of these events without changing the underlying physics. That's what our software does; they make impossible things possible.
Lee built on the work of scientists Galli and de Pablo. Several other scientists were involved in code coupling over the years, including Francois Gygi at the University of California, Davis, and Jonathan Whitmer at Notre Dame University. The outcome is a powerful new tool that combines quantum theory and simulations to investigate vacancies. This will apply to other promising quantum materials.
Galli said that they are just at the beginning. We want to be able to do our computations much faster, so that we can determine what the best defects are for different applications.
Lee et al, Stability and molecular pathways to the formation of spin defects in Silicon carbide, Nature Communications, is available. There is a DOI of 10.1038/s41467-021-26419-0.
Nature Communications is a journal.
How to transform vacancies into quantum information was retrieved fromphys.org on December 15, 2021.
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