An artistic impression showing the incorporation of single photon emitters during the hBN growth. Photo credit: Trong Toan Tran
The study helps to unlock the chemical structure of defects that individual photons emit.
Systems that can emit a stream of single photons, called quantum light sources, are critical hardware components for new technologies such as: Quantum computing, the quantum internet and quantum communication.
In many cases, the ability to generate quantum light when needed requires the manipulation and control of individual atoms or molecules in order to push the boundaries of modern manufacturing techniques and make the development of these systems an interdisciplinary challenge.
In new research published in Natural materials, an international multidisciplinary collaboration led by the University of Technology Sydney (UTS), has revealed the chemical structure behind defects in white Graph (hexagonal boron nitride, hBN), a two-dimensional nanomaterial showing promise as a platform for the generation of quantum light.
The defects or crystal imperfections can act as single photon sources, and an understanding of their chemical structure is critical in order to manufacture them in a controlled manner.
“Individual photon emitters from hBN have excellent optical properties that are among the best of all solid-state material systems. In order to be able to use it in practice, however, we have to understand the nature of the defect and finally start to solve this mystery, ”says UTS PhD student Noah Mendelson and lead author of the study.
“Unfortunately, we cannot simply combine powerful techniques to visualize individual atoms directly with quantum optical measurements. Therefore, it is very difficult to obtain this structural information. Instead, we approached this problem from a different angle by controlling the incorporation of dopants like carbon into hBN during growth and then directly comparing the optical properties for each problem, ”he said.
To accomplish this comprehensive study, the team, led by Professor Igor Aharonovich, chief researcher of the UTS Node of the ARC Center of Excellence in Transformative Meta-Optic Materials (TMOS), reached out to staff in Australia and around the world to deploy the array of samples needed.
For the first time, the researchers were able to observe a direct connection between the incorporation of carbon into the hBN lattice and quantum emission.
“Determining the structure of material defects is an incredibly challenging problem and requires experts from many disciplines. We couldn’t have done this alone in our group. Only when we partner with employees from around the world who have expertise in various material growth techniques can we fully investigate this problem. Together we were finally able to create the clarity that is needed for the entire research community, ”said Professor Aharonovich.
“It was especially exciting as this study was made possible by the new collaborative effort with staff members Dipankar Chugh, Hark Hoe Tan and Chennupati Jagadish from the TMOS node on Australian National University, ” he said.
In their study, the scientists identified another fascinating feature: the defects carry spin, a fundamental quantum mechanical property and a key element in coding and retrieving quantum information stored on individual photons.
“Confirming that these defects carry spin opens up exciting opportunities for future quantum sensor applications, especially with atomically thin materials.” Professor Aharonovich said.
The work brings a new type of research field, 2D quantum spintronics, to the fore and forms the basis for further investigations into quantum light emission from hBN. The authors assume that their work will spark increased interest in this area and enable a number of follow-up experiments, for example the generation of entangled photon pairs from hBN, detailed studies of the system’s spin properties, and the theoretical confirmation of the defect structure.
“This is just the beginning, and we expect our results to accelerate the adoption of hBN quantum emitters in a number of new technologies,” Mendelson concludes.
Reference: “Identification of Carbon as a Source of Visible Single Photon Emission from Hexagonal Boron Nitride” by Noah Mendelson, Dipankar Chugh, Jeffrey R. Reimers, Zinn S. Cheng, Andreas Gottscholl, Hu Long, Christopher J. Mellor, Alex Zettl, Vladimir Dyakonov, Peter H. Beton, Sergei V. Novikov, Chennupati Jagadisch, Hark Hoe Tan, Michael J. Ford, Milos Toth, Carlo Bradac and Igor Aharonovich, November 2, 2020, Natural materials.
DOI: 10.1038 / s41563-020-00850-y
Funding: Australian Research Council, Asian Bureau for Aerospace Research and Development, US Department of Energy, National Computer Infrastructure (NCI), Intersect, Shanghai University, Chinese National Science Foundation, German Research Foundation
Researchers from Shanghai University, the University of Nottingham, the University of Würzburg, the University of California – Berkeley and Trent University were also involved in the study.
