QUantum emitters in semiconductors for future TEchnologies

Quantum technology is the application of quantum mechanical principles in technical applications such as communication, cryptography and sensors, and this technology has received massive attention in recent years. The most well-known realizations of quantum technology are based on superconductors, but these must operate at very low temperatures (typically millikelvin), extremely stable platforms and are difficult to scale compared to the modern transistor. More recently, point defects in semiconductors have been proposed as an alternative platform for quantum technology, so-called quantum defects, since they can potentially operate at room temperature, are suitable as nanoscale sensors, and can be used as single-photon sources. The single-photon property of these quantum defects are important in many quantum technology applications and a strength of the point defect platform, and this is also central to the QuTe project. The main focus in the project so far has been on quantum defects in silicon carbide (SiC), but there is also activity on Silicon, and on exploring and finding new materials with quantum defects. Regarding the latter, we have conducted and published a large study where we utilize the large material databases combined with machine learning algorithms to find potential material platforms for quantum defects [O. L. Hebnes, M. E. Bathen, …, L. Vines and M. Hjorth-Jensen, npj Computational Materials 8, 207 (2022)]. We are currently following up on some of these materials, in particular Aluminum Nitride (AlN) In the field of SiC, we have addressed issues related to the formation, identification and control of point defects in the most common polytype of SiC (so-called 4H-SiC), but also studied other polytypes such as 6H-SiC. The work has resulted in several papers. An important activity in the project has been to look at the effects of electric field, and how this affects the single-photon emission. Another important activity in the project is to develop theoretical methods to model the luminescence from quantum defects, for all the relevant materials in the project, and we hope to publish much of this work in the coming year. The studies of quantum defects in silicon, however, have been more demanding. Among other things, we have looked at the formation and possibility of one-photon from selected defects, in addition to theoretical studies. Here, too, we hope to be able to publish some of this in the coming year.

Quantum technology (QT) promises massive impacts on fields ranging from communication and cryptography to sensing and computing. Point defects in semiconductors are among the promising platforms to deploy quantum technology and are the subject of an immense international research interest, offering a wafer platform suitable for scaling, miniaturization and room temperature operation. Essential to many point defect based QT components is the single photon emitter, and a deeper understanding of how an ideal SPS functions and interacts with its environment will have a profound impact. The QuTe project explores several underdeveloped topics of point defects in silicon and silicon carbide for QT applications, and involves identification of new SPEs, charge state identification and control, and manipulation and tuning of the emission wavelength, as well as theoretical modeling. The overarching research questions in the QuTe project are: i) What are the origins of the single photon emission signatures observed in Si and SiC, and in what charge state do they act as SPE? ii) how can SPEs be manipulated to tune the emission wavelength, e.g. to obtain indistinguishable photons ? iii) can we employ quantum chemical calculations to reveal more information about the absorption and emission from SPEs, including time dependent information? To address these questions, we will employ electro-optical defect characterization, ion implantation, nano-structuring of semiconductor materials and advanced theoretical modeling to develop the understanding and controlled manipulations of the SPEs. In particular, the defect identifications will be a foundational task for the project. With this we hope to accelerate the process of utilizing point defects in semiconductors as building blocks for quantum technology, and we believe that QuTe will greatly enhance the visibility for QT in Norway, which is strategically important and well synchronized with the dawn of the global quantum era.