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March 17, 2025

Twisting 2D materials creates artificial atoms that could advance quantum computers

Credit: Nano Letters (2025). DOI: 10.1021/acs.nanolett.5c00456
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Credit: Nano Letters (2025). DOI: 10.1021/acs.nanolett.5c00456

By taking two flakes of special materials that are just one atom thick and twisting them at high angles, researchers at the University of Rochester have unlocked unique optical properties that could be used in quantum computers and other quantum technologies.

In a new study in Nano Letters, the researchers show that precisely layering nano-thin materials creates excitons—essentially, artificial atoms—that can act as quantum information bits, or qubits.

"If we had just a single layer of this material we're using, these dark excitons wouldn't interact with light," says Nickolas Vamivakas, the Marie C. Wilson and Joseph C. Wilson Professor of Optical Âé¶¹ÒùÔºics. "By doing the big twist, it turns on artificial atoms within the material that we can control optically, but they are still protected from the environment."

Moiré is less

The work builds on the 2010 Nobel Prize–winning discovery that peeling carbon apart until it reaches a single layer of atoms creates a new two-dimensional (2D) material called graphene with special quantum characteristics.

Scientists have since explored how the optical and electrical properties of graphene and other 2D materials change when layered on top of one another and twisted at very small angles—called moiré superlattices. For example, when graphene is twisted at the "magic" angle of 1.1 degrees, it creates special patterns that produce properties such as superconductivity.

Vamivakas and his fellow researchers place monolayer materials in chips that are cooled through a cryostat to observe their unique optical properties. Credit: University of Rochester photo / J. Adam Fenster
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Vamivakas and his fellow researchers place monolayer materials in chips that are cooled through a cryostat to observe their unique optical properties. Credit: University of Rochester photo / J. Adam Fenster

But scientists from Rochester's Institute of Optics and Department of Âé¶¹ÒùÔºics and Astronomy took a different approach. They used molybdenum diselenide, a 2D material that is more fickle than , and twisted it at much higher angles of up to 40 degrees. Still, the researchers found the twisted monolayers produced excitons that were able to retain information when activated by light.

"This was very surprising for us," says Arnab Barman Ray, an optics Ph.D. candidate. "Molybdenum diselenide is notorious because other materials in the family of moiré materials show better information-retaining capacity. We think that if we use some of those other materials at these large angles, they will probably work even better."

The team views this as an important early step toward new types of quantum devices.

"Down the line, we hope these can be used like memory or nodes in a quantum network, or put into optical cavities to create quantum materials," says Vamivakas. "These could be the backbone for devices like the next generation of lasers or even tools to simulate quantum physics."

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More information: Arnab Barman Ray et al, Diffusion of Valley-Coherent Dark Excitons in a Large-Angle Incommensurate Moiré Homobilayer, Nano Letters (2025).

Journal information: Nano Letters

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Twisting two-dimensional materials at high angles creates artificial atoms with unique optical properties, potentially advancing quantum computing. By layering molybdenum diselenide, excitons are formed that can act as qubits, retaining information when activated by light. This approach differs from previous methods using moiré superlattices and could lead to new quantum devices and technologies.

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