2D Material Identified That Can Store Quantum Information at Room Temperature

Artistic rendering of isolated spins on hexagonal boron nitride under a light microscope. Photo credit: Qiushi Gu

Researchers have identified a two-dimensional material that could be used to store quantum information at room temperature.

Quantum memory is a key building block that needs to be addressed in building a quantum internet, where quantum information is securely stored and sent via photons, or particles of light.

Researchers at the University of Cambridge’s Cavendish Laboratory, in collaboration with colleagues from UT Sydney in Australia, have identified a two-dimensional material, hexagonal boron nitride, that can emit single photons at room temperature from atomic-scale defects in its structure.

Researchers discovered that the light emitted by these isolated defects provides information about a quantum property that can be used to store quantum information, called spin, meaning the material could be useful for quantum applications. Importantly, the quantum spin is accessible via light and at room temperature.

The finding could eventually support scalable quantum networks made of two-dimensional materials that can operate at room temperature. The results are published in the journal nature communication.

Future communication networks will use single photons to send messages around the world, leading to more secure global communication technologies.

Computers and networks based on the principles of quantum mechanics would be both far more powerful and safer than current technologies. However, to enable such networks, researchers need to develop reliable methods to generate single, indistinguishable photons as information carriers across quantum networks.

“We can send information from one place to another using photons, but if we want to build real quantum networks, we need to send information, store it and send it somewhere else,” said Dr. Hannah Stern of the Cavendish Laboratory in Cambridge. Co-first author of the study, along with Qiushi Gu and Dr. John Jarman. “We need materials that can store quantum information for a period of time at room temperature, but most of the current material platforms that we have are difficult to fabricate and only work well at low temperatures.”

Hexagonal boron nitride is a two-dimensional material grown by chemical vapor deposition in large reactors. It’s cheap and scalable. Recent efforts have revealed the existence of single photon emitters and the presence of a dense ensemble of optically accessible spin but not individually isolated spin-photon interfaces operating under ambient conditions.

“Typically, it’s a pretty boring material that’s typically used as an insulator,” said Stern, a junior research fellow at Trinity College. “But we found that there are defects in this material that can emit single photons, which means it could be used in quantum systems. If we manage to store quantum information in the spin, then it’s a scalable platform.”

Stern and her colleagues set up a hexagonal boron nitride sample near a tiny gold antenna and a fixed-strength magnet. By firing a laser at the sample at room temperature, they were able to observe many different magnetic-field-dependent responses to the light emitted by the material.

The researchers found that by aiming the laser at the material, they were able to manipulate the spin, or inherent angular momentum, of the defects and use the defects as a way to store quantum information.

“Usually the signal in these systems is always the same, but in this case the signal changes depending on the specific defect we’re investigating, and not all defects show a signal, so there’s still a lot to discover,” he said. First author Qiushi Gu. “There’s a lot of variation across the material, like a blanket draped over a moving surface – you see a lot of waves, and they’re all different.”

Professor Mete Atature, who supervised the work, adds: “Having identified optically accessible isolated spins at room temperature in this material, the next steps will be to understand their photophysics in detail and the operational regimes for potential applications, including information storage and.” to investigate quantum sensors. After this work there will be a stream of fun physics.”

Reference: “Magnetic Resonance Optically Captured at Room Temperature of Single Defects in Hexagonal Boron Nitride” by Hannah L. Stern, Qiushi Gu, John Jarman, Simone Eizagirre Barker, Noah Mendelson, Dipankar Chugh, Sam Schott, Hoe H. Tan, Henning Sirringhaus, and Igor Aharonovich Mete Atatüre, February 1, 2022, nature communication.
DOI: 10.1038/s41467-022-28169-z

The research was partially supported by the European Research Council. Mete Atature is a Fellow of St John’s College, Cambridge.