Adding Quantum to Your Computer

Introducing the Quantum Upgrade to Your Computer.

Computers that can use the "spooky" properties of quantum mechanics to solve problems faster than current technology may sound interesting, but they must first get past a big problem. Scientists from Japan may have found the answer by showing how a superconducting material called niobium nitride can be added to a nitride-semiconductor substrate as a flat, crystalline layer. With this method, it might be easy to make quantum bits that can be used with regular computers.

Conventional ways of making silicon microprocessors have improved and grown over many years, and they continue to do so. On the other hand, most quantum computer architectures have to be made from scratch. But finding a way to put both quantum and traditional logic units on the same chip or adding quantum capabilities to existing production lines could speed up the use of these new systems by a lot.

Scientists from the University of Tokyo's Institute of Industrial Science recently showed that thin layers of niobium nitride (NbNx) can grow right on top of layers of aluminium nitride (AlN). Niobium nitride can become superconducting at temperatures less than 16 degrees Celsius above absolute zero. Because of this, it can be put together in a structure called a Josephson junction to make a superconducting qubit.

Scientists looked at how temperature affected the crystal structures and electrical properties of thin films of NbNx grown on AlN templates. They showed that the way the atoms in the two materials were spaced was similar enough that flat layers could be made.

"Because aluminium nitride and niobium nitride have small differences in their lattices, we found that a highly crystalline layer could grow at the interface," says first author and corresponding author Atsushi Kobayashi.

X-ray diffraction was used to figure out how crystalline the NbNx was, and atomic force microscopy was used to take a picture of the surface topology. X-ray photoelectron spectroscopy was also used to check the chemical composition. The team showed how the growth conditions, especially the temperature, affected how the atoms were arranged, how much nitrogen was in the material, and how well it conducted electricity.

Atsushi Kobayashi says, "The fact that the two materials are built similarly makes it easier to put superconductors into semiconductor optoelectronic devices."

Also, the sharply defined interface between the AlN substrate, which has a wide bandgap, and the superconductor NbNx is important for future quantum devices like Josephson junctions. superconducting layers that are only a few feet