Future communication networks are expected to use single photons to send messages worldwide. This will lead to more secure global communication technologies.
Quantum computers will be more powerful and more secure than current technologies in the future. However, to make such networks possible, scientists first have to develop reliable generating single, indistinguishable photons as carriers of information across quantum networks.
Building quantum networks require sending information, storing and sending it somewhere else. Existing materials for storing quantum information are challenging to make and only work well at low temperatures. Hence, we need materials that work at room temperature as well.
Scientists from the Cavendish Laboratory at the University of Cambridge, in collaboration with UT Sydney in Australia, have identified 2D material that can emit single photons from atomic-scale defects in its structure at room temperature. The material, hexagonal boron nitride, is cheap and scalable.
It was found that the light emitted from these isolated defects gives information about a quantum property. This property can be used to store quantum information, called spin. Notably, the quantum spin can be accessed via light and at room temperature.
Dr. Hannah Stern from Cambridge’s Cavendish Laboratory, the study’s co-first author, along with Qiushi Gu and Dr. John Jarman, said, “Usually, Hexagonal boron nitride is a boring material that’s normally used as an insulator. 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 can get it to store quantum information in spin, then it’s a scalable platform.”
Scientists set up the material sample near a tiny gold antenna and a magnet of set strength. They then fired laser beams at the sample at room temperature to observe several magnetic field-dependent responses to the light being emitted from the material.
Scientists found that by shining a laser on the material, they could manipulate the spin or inherent angular momentum of the defects and use the defects as a way of storing quantum information.
Co-first author Qiushi Gu said, “Typically, the signal is always the same in these systems, but in this case, the signal changes depending on the particular defect we’re studying, and not all defects show a signal, so there is a lot to discover still. There’s a lot of variation across the material like a blanket draped over a moving surface – you see lots of ripples, and they’re all different.”
Professor Mete Atature, who supervised the work, adds, “now that we have identified optically accessible isolated spins at room temperature in this material, the next steps will be to understand their photophysics in detail and explore the operation regimes for possible applications including information storage and quantum sensing. There will be a stream of fun physics following this work.”
- Stern, H.L., Gu, Q., Jarman, J. et al. Room-temperature optically detected magnetic resonance of single defects in hexagonal boron nitride. Nat Commun 13, 618 (2022). DOI: 10.1038/s41467-022-28169-z