New research unveils properties for storage of quantum information and computer science

Researchers at the Rensselaer Polytechnic Institute have developed a way to manipulate the promising two-dimensional tungsten diselenide (WSe2) material to further unlock its potential for faster and more efficient processing, as well as processing and storage of quantum information. Their conclusions were published today in Nature Communications.

Around the world, researchers have focused heavily on a class of two-dimensional atomic semiconductor materials, known as monolayer transition metal dichalcogenides. These atomically thin semiconductor materials – less than 1 nm thick – are attractive as industry tries to make devices smaller and more energy efficient.

"It's a completely new paradigm," said Sufei Shi, assistant professor in chemical and biological engineering at Rensselaer and corresponding author of the journal. "The benefits could be huge."

Shi and his research team, in partnership with clean room staff at the Rensselaer Center for Materials, Devices and Integrated Systems, have developed a method for isolating these thin layers of WSe2 from crystals in order to stack them with other atomically thin materials such as boron nitride and graphene.

When the WSe2 layer is sandwiched between two flakes of boron nitride and interacts with light, said Shi Shi, a single process occurs. Unlike traditional semiconductors, electrons and holes bind strongly and form a quasi-particle of neutral charge called exciton.

"Exciton is probably one of the most important concepts in light-matter interaction. Essential understanding for the recovery of solar energy, efficient light-emitting diode devices and almost everything related to the properties optical semiconductors, "said Shi a member of Rensselaer's Electrical, Computer and Systems Engineering Department. "Now we have discovered that it can actually be used for storage and processing of quantum information."

One of the interesting properties of the exciton in WSe2, he said, is a new quantum degree of freedom now called "valley spin", an increased freedom of movement of the particles sought for the ## EQU1 ## 39, quantum computing. But, explains Shi, excitons do not usually have a long life, which makes them impractical.

In an earlier publication in Nature CommunicationsShi and his team have discovered a special "dark" exciton that can not usually be seen, but lasts longer. His challenge is that the "dark" exciton lacks the quantum degree of "waltz-spin" quantum freedom.

In this recent research, Shi and his team have discovered how to lighten the "dark" exciton; that is to say, to make the "dark" exciton interact with another quasi-particle called phonon to create a completely new quasi-particle possessing the two properties sought by the researchers.

"We found the perfect place," said Shi. "We've found a new quasi-particle that has a quantum degree of freedom and a long lifespan, which is why it's so exciting.We have the quantum property of the" brilliant "exciton, but also the long life of the "dark" exciton. "

The team's findings, said Shi, laid the foundation for the future development of the next generation of computer peripherals and storage.

In Rensselaer, Shi was joined in this publication by postdoctoral scholar Zhipeng Li and graduate students Tianmeng Wang and Zhen Lian, all from the Department of Chemical and Biological Engineering. This research was also conducted in close partnership with the National Laboratory of High Magnetic Fields and other research institutes.