Silicon-vacancy (SiV) color centers in diamond offer a promising system for quantum information applications owing to their intense narrowband emission and optically detectable spin states. Here, the fluorescent properties of ensembles and single SiV centers in diamonds obtained by high-pressure high-temperature synthesis from adamantane (below referred to as adamantane diamonds) are investigated at liquid-helium temperatures. Ensembles of SiV centers (~10³) are studied in large diamond crystals (1–2 µm in size). Despite the large number of excited centers, the fine structure of the zero-phonon line, corresponding to four allowed optical transitions between the ground- and excited-state doublets of the SiV center, can be observed in the fluorescence spectra of these crystals. The width of individual lines is in the range of 60–80 GHz, which is explained by their inhomogeneous broadening. Single SiV centers are studied in diamond crystallites with sizes of about 200 nm. The width of the narrowest transition lines observed in the fluorescence spectra of single SiV centers under resonant excitation is almost three orders of magnitude smaller than linewidths in the spectra of SiV ensembles and is as small as 94 MHz; i.e., these lines are so narrow that their width is determined by the lifetime of the upper state of the transition. Therefore, adamantane nanodiamond features the narrowest emission line width of a single SiV center at cryogenic temperatures among other types of SiV-con-taining nanodiamonds of similar sizes obtained by the high-pressure high-temperature and chemical vapor deposition techniques.

中文翻译：

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在“金刚烷”纳米金刚石中单SiV中心的光学跃迁进行傅立叶变换的有限线宽

钻石中的硅空位（SiV）颜色中心由于其强烈的窄带发射和光学可检测的自旋态，为量子信息应用提供了一个有希望的系统。在此，在液氦温度下研究了由金刚烷高压高温合成获得的钻石（以下称为金刚烷钻石）中的合奏和单个SiV中心的荧光特性。SiV中心的合奏（〜10 ³）是在大型钻石晶体（尺寸为1-2 µm）中研究的。尽管存在大量激发中心，但在这些晶体的荧光光谱中仍可以观察到零声子线的精细结构，其对应于SiV中心基态和激发态双峰之间的四个允许的光学跃迁。每条线的宽度在60–80 GHz的范围内，这可以通过它们的不均匀加宽来解释。在尺寸约为200 nm的金刚石微晶中研究了单SiV中心。单个SiV中心在共振激发下的荧光光谱中观察到的最窄过渡线的宽度比SiV集成体光谱中的线宽小将近三个数量级，小至94 MHz。即 这些线太窄，以致于它们的宽度取决于过渡的上态的寿命。因此，在通过高温高压和化学气相沉积技术获得的尺寸相似的其他类型的含SiV的纳米金刚石中，金刚烷纳米金刚石在低温下具有单个SiV中心的最窄发射线宽度。