Silicon-vacancy Charge Dynamics Boosted Sixfold in Nanodiamonds with Tailored Nitrogen Concentrations

Silicon-vacancy centres within diamond are promising candidates for quantum technologies, but achieving bright, stable emission remains a significant challenge. A. A. Zhivopistsev, A. M. Romshin, and A. V. Gritsienko, along with colleagues at various institutions, now demonstrate a method for dramatically boosting the light output from these centres. The team achieves a sixfold enhancement of luminescence by simultaneously illuminating the diamond with both red and green light. This technique appears to suppress an inactive state within the silicon-vacancy centre. This research provides a crucial step towards creating practical, scalable quantum emitters based on nanodiamonds, potentially enabling advances in sensing, imaging, and quantum communication.

Technology (MIPT), Dolgoprudny, Russia, and the P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow, Russia, with contributions from the Russian Quantum Center and the Ioffe Institute, St. The team investigated the charge dynamics of silicon-vacancy (SiV) centers within high-pressure, high-temperature nanodiamonds (NDs) containing varying concentrations of substitutional nitrogen (NS).

This research addresses a critical need for understanding and controlling the properties of these defects, which are promising candidates for quantum technologies. The study demonstrates a controlled enhancement of SiV photoluminescence, a key metric for their performance in quantum applications. By systematically varying the concentration of NS, researchers sought to understand how these impurities influence the charge state and optical properties of SiV centers within the nanodiamond lattice. Nanodiamonds were synthesized via a high-pressure, high-temperature (HPHT) method from a mixture of adamantane and detonation nanodiamonds (DND), with varying ratios used to control nitrogen concentration.

Ratios tested included 2:1, 10:1, 100:1, 300:1, 1000:1, and 10000:1, resulting in estimated concentrations of 500 ppm, 150 ppm, 20 ppm, 4 ppm, 1. 5 ppm, and 0. 2 ppm respectively. The NDs were characterized using a range of techniques including electron paramagnetic resonance (EPR) spectroscopy, scanning electron microscopy (SEM), confocal microscopy, photoluminescence (PL) spectroscopy, time-resolved PL spectroscopy, and second-order correlation function (g2(τ)) measurements. PL spectra revealed characteristic peaks of H3 centers, NV0, NV-, and SiV centers, with the SiV zero-phonon line exhibiting a full width at half maximum of approximately 5 nm. This supplementary information provides a detailed account of the materials, methods, and experimental setup, allowing for reproducibility and a deeper understanding of the results.

Green Light Boosts Silicon-Vacancy Luminescence Sixfold

Scientists have achieved a sixfold enhancement of luminescence from silicon-vacancy (SiV) centers within nanodiamonds, demonstrating precise control over their optical properties. This breakthrough stems from a dual-color excitation technique, combining strong red illumination at 660 nm with weak green light at 530 nm, and unlocks new possibilities for quantum photonic devices. Experiments reveal that the addition of green light effectively suppresses an inactive SiV state, significantly boosting the brightness of these quantum emitters. The team systematically investigated nanodiamonds synthesized with varying concentrations of substitutional nitrogen, ranging from 500 ppm to 0.

15 ppm, to understand the role of this impurity in SiV emission dynamics. Detailed analysis of luminescence intensity and lifetime dependencies on excitation wavelength confirms the involvement of donor nitrogen in the charge state of SiV centers. Researchers observed that luminescence intensity under green excitation consistently exceeded that under red excitation, averaging a 2. 1-fold increase. Further investigation revealed a saturation behavior in SiV luminescence, where the saturation power under red excitation was approximately two times lower than under green excitation. These findings demonstrate that the green light actively controls the charge state of the SiV centers, preventing them from entering an optically dark state. By precisely manipulating the charge environment, scientists have not only enhanced luminescence but also paved the way for engineering scalable and optically-controlled quantum emitters based on SiV-luminescent diamond nanoparticles, promising advancements in quantum computing, sensing, and imaging technologies.

Nitrogen Impurities Boost Silicon-Vacancy Luminescence

This research details a significant enhancement in the luminescence of silicon-vacancy (SiV) centres within nanodiamonds, achieved through a specific dual-colour light excitation. Scientists observed a sixfold increase in light emission by combining strong red illumination with weaker green light, demonstrating a controlled manipulation of the SiV centre’s behaviour. The findings strongly suggest that the presence of nitrogen impurities within the nanodiamonds plays a crucial role in this process, actively participating in the emission dynamics of the SiV centre. The team’s measurements of fluorescence lifetime and intensity, coupled with the observed dependence on nitrogen concentration, provide clear evidence that nitrogen atoms donate charge to the SiV centre, suppressing an inactive state and boosting light output. This controlled charge transfer unlocks a pathway towards creating brighter and more reliable light emitters based on nanodiamonds, with potential applications in quantum technologies. The authors highlight future research directions, including investigating charge transport in magnetic fields and exploring the possibility of creating hybrid quantum systems where nitrogen acts as a spin register and the SiV centre facilitates optical control and readout, potentially leading to the development of scalable quantum memories and multi-addressable quantum nodes.