Hexagonal boron-nitride (hBN) is a two-dimensional material with various everyday uses in cosmetics, dental cement, and laser printing, to name a few. Now, research on hBN co-authored by Dr. Carlo Bradac, professor of Physics & Astronomy at Trent, could have significant implications for a range of quantum applications, including encryption of information, sensing and material science.

The study, published in Nature Materials, highlights a deeper understanding of the light-emitting impurities found in hBN - inclusions of foreign atoms in hBN which remarkably preserve their quantum properties at room temperature. In the past few years, they have been widely used in applications ranging from 2D opto-electronics to super-resolution imaging, yet little was known about what these impurities consist of. The study gives insight into the chemical structure of these atom-like hBN impurities—notably that they involve carbon atoms within the honeycomb hBN structure made of alternating nitrogen and boron atoms.

“We learned more about the nature of single photon sources in hBN,” explains Professor Bradac, who joined the Physics department at Trent in July 2020. “That’s useful for understanding and, ultimately, tailoring their properties for specific applications such as quantum key distribution. Instead of transferring information by lasers through optical fibres, data are transferred with single photons of light — the advantage being that information transmitted this way cannot be stolen by a third party without the sender and receiver knowing the information has been compromised. So, it’s working towards completely secure communications.”

A pragmatic solution to for quantum computing

Prof. Bradac notes that the study could have significant implications for future quantum computing architectures. In 2019, Google, as one of the few big companies involved in the advancement of quantum computers, announced “quantum supremacy”, stating that it has created a processor that could perform calculations, which would instead take the most powerful classic computers days, within seconds. However, the Google processor can only operate at extremely cold temperatures — close to absolute zero. In contrast, the research Prof. Bradac is working on points towards applications that could ultimately function at room temperature, a much more pragmatic solution — albeit a challenging one given the current state of our technology.

Possible implications for quantum sensing technology

While quantum computing has grabbed most of the headlines in recent years, Prof. Bradac is more interested in the implications these hBN emitters have for quantum sensing. This field includes quantum-based technologies, which promise to improve our measurement capabilities beyond those of our best classical approaches: from detecting individual spins in spintronic devices to sensing and imaging biological processes with single-protein and single-molecule resolution within cells.

The study brings scientists one step closer to unravelling the chemical and atomic structure of emitters in hBN, creating a better understanding of their photon dynamics and the possibility of tailoring their properties.

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