For the first time, scientists in the Femtosecond Spectroscopy Unit at the Okinawa Institute of Science and Technology (OIST) have directly tracked how dark excitons evolve in atomically thin materials. This achievement paves the way for advances in both classical and quantum information technologies. The study was published in Nature Communications.

Professor Keshav Dani, who leads the unit, emphasized the importance of the work: “Dark excitons have great potential as information carriers, because they are inherently less likely to interact with light, and hence less prone to degradation of their quantum properties. However, this invisibility also makes them very challenging to study and manipulate. Building on a previous breakthrough at OIST in 2020, we have opened a route to the creation, observation, and manipulation of dark excitons.”

“In the general field of electronics, one manipulates electron charge to process information,” explains Xing Zhu, co-first author and PhD student in the unit. “In the field of spintronics, we exploit the spin of electrons to carry information. Going further, in valleytronics, the crystal structure of unique materials enables us to encode information into distinct momentum states of the electrons, known as valleys.”

The ability to use the valley dimension of dark excitons to carry information positions them as promising candidates for quantum technologies. Dark excitons are by nature more resistant to environmental factors like thermal background than the current generation of qubits, potentially requiring less extreme cooling and making them less prone to decoherence, where the unique quantum state breaks down.