Efficient nitrogen-vacancy centers' fluorescence excitation and collection from micrometer-sized diamond by a tapered optical fiber

Efficiently excite nitrogen-vacancy (NV) centers in diamond and collect their fluorescence significantly benefit the fiber-optic-based NV sensors. Here, using a tapered optical fiber (TOF) tip, we significantly improve the efficiency of the laser excitation and fluorescence collection of the NV, thus enhance the sensitivity of the fiber-optic based micron-sized diamond magnetic sensor. Numerical calculation shows that the TOF tip delivers a high numerical aperture (NA) and has a high fluorescence excitation and collection efficiency. Experiments demonstrate that using such TOF tip can obtain up to over 7-fold the fluorescence excitation efficiency and over15-fold the fluorescence collection efficiency of a flat-ended (non-TOF) fiber. Such fluorescence collection enhances the sensitivity of the optical fiber-based diamond NV magnetometer, thus extending its potential application region.Comment: 11 pages, 13 figure

Enhancing fluorescence excitation and collection from the nitrogen-vacancy center in diamond through a micro-concave mirror

We experimentally demonstrate a simple and robust optical fibers based method to achieve simultaneously efficient excitation and fluorescence collection from Nitrogen-Vacancy (NV) defects containing micro-crystalline diamond. We fabricate a suitable micro-concave (MC) mirror that focuses scattered excitation laser light into the diamond located at the focal point of the mirror. At the same instance, the mirror also couples the fluorescence light exiting out of the diamond crystal in the opposite direction of the optical fiber back into the optical fiber within its light acceptance cone. This part of fluorescence would have been otherwise lost from reaching the detector. Our proof-of-principle demonstration achieves a 25 times improvement in fluorescence collection compared to the case of not using any mirrors. The increase in light collection favors getting high signal-to-noise ratio (SNR) optically detected magnetic resonance (ODMR) signals hence offers a practical advantage in fiber-based NV quantum sensors. Additionally, we compacted the NV sensor system by replacing some bulky optical elements in the optical path with a 1x2 fiber optical coupler in our optical system. This reduces the complexity of the system and provides portability and robustness needed for applications like magnetic endoscopy and remote-magnetic sensing.Comment: 6 pages, 8 figure

Complete coherent control of silicon vacancies in diamond nanopillars containing single defect centers

Arrays of identical and individually addressable qubits lay the foundation for the creation of scalable quantum hardware such as quantum processors and repeaters. Silicon-vacancy (SiV) centers in diamond offer excellent physical properties such as low inhomogeneous broadening, fast photon emission, and a large Debye–Waller factor. The possibility for all-optical ultrafast manipulation and techniques to extend the spin coherence times makes them promising candidates for qubits. Here, we have developed arrays of nanopillars containing single (SiV) centers with high yield, and we demonstrate ultrafast all-optical complete coherent control of the excited state population of a single SiV center at the optical transition frequency. The high quality of the chemical vapor deposition (CVD) grown SiV centers provides excellent spectral stability, which allows us to coherently manipulate and quasi-resonantly read out the excited state population of individual SiV centers on picosecond timescales using ultrafast optical pulses. This work opens new opportunities to create a scalable on-chip diamond platform for quantum information processing and scalable nanophotonics applications

Strongly cavity-enhanced spontaneous emission from silicon-vacancy centers in diamond

Quantum emitters are an integral component for a broad range of quantum technologies, including quantum communication, quantum repeaters, and linear optical quantum computation. Solid-state color centers are promising candidates for scalable quantum optics due to their long coherence time and small inhomogeneous broadening. However, once excited, color centers often decay through phonon-assisted processes, limiting the efficiency of single-photon generation and photon-mediated entanglement generation. Herein, we demonstrate strong enhancement of spontaneous emission rate of a single silicon-vacancy center in diamond embedded within a monolithic optical cavity, reaching a regime in which the excited-state lifetime is dominated by spontaneous emission into the cavity mode. We observe 10-fold lifetime reduction and 42-fold enhancement in emission intensity when the cavity is tuned into resonance with the optical transition of a single silicon-vacancy center, corresponding to 90% of the excited-state energy decay occurring through spontaneous emission into the cavity mode. We also demonstrate the largest coupling strength (g/2π = 4.9 ± 0.3 GHz) and cooperativity (C = 1.4) to date for color-center-based cavity quantum electrodynamics systems, bringing the system closer to the strong coupling regime

Cavity-enhanced Raman emission from a single color center in a solid

We demonstrate cavity-enhanced Raman emission from a single atomic defect in a solid. Our platform is a single silicon-vacancy center in diamond coupled with a monolithic diamond photonic crystal cavity. The cavity enables an unprecedented frequency tuning range of the Raman emission (100 GHz) that significantly exceeds the spectral inhomogeneity of silicon-vacancy centers in diamond nanostructures. We also show that the cavity selectively suppresses the phonon-induced spontaneous emission that degrades the efficiency of Raman photon generation. Our results pave the way towards photon-mediated many-body interactions between solid-state quantum emitters in a nanophotonic platform

Functional analysis of GbAGL1, a D-lineage gene from cotton (Gossypium barbadense)

Cotton fibres originate from the outer ovule integument and D-lineage genes are essential for ovule development and their roles can be described by the ‘ABCDE’ model of flower development. To investigate the role of D-lineage genes during ovule and fibre development, GbAGL1 (GenBank accession number: FJ198049) was isolated from G. barbadense by using the SMART RACE strategy. Sequence and phylogenetic analyses revealed that GbAGL1 was a member of the D-lineage gene family. Southern blot analysis showed that GbAGL1 belonged to a low-copy gene family. Semi-quantitative RT-PCR and RNA in situ hybridization analyses revealed that the GbAGL1 gene in G. barbadense was highly expressed in whole floral bud primordia and the floral organs including ovules and fibres, but the signals were barely observed in vegetative tissues. GbAGL1 expression increased gradually with the ovule developmental stages. Over-expression of GbAGL1 in Arabidopsis caused obvious homeotic alternations in the floral organs, such as early flowering, and an extruded stigma, which were the typical phenotypes of the D-lineage gene family. In addition, a complementation test revealed that GbAGL1 could rescue the phenotypes of the stk mutant. Our study indicated that GbAGL1 was a D-lineage gene that was involved in ovule development and might play key roles in fibres development

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Manipulation and Bioimaging Applications of Fluorescent Nanodiamonds

鑽石是碳的同素異形體。不同於其它碳材料的獨特性質是，鑽石具有光學透明性，而常含有氮元素的缺陷，此缺陷可當作發光中心。帶負電荷的氮空位的缺陷，是在鑽石中最值得一提的發光中心，因為發出具有高穩定性的遠紅外螢光。這種獨特的光學特性結合良好的生物相容性，使奈米尺寸的鑽石在生物成像中，成為有潛力的螢光探針，尤其是細胞追蹤研究上。首先，我們利用小於20奈米的螢光奈米鑽石作為螢光共振能量轉移的供體和近紅外螢光染料作為受體。此螢光共振能量轉移的效率是大約7%。緊接著，針對螢光奈米鑽石，我們建立一套超高解析度的受激發射損耗顯微術系統（STED），展示出奈米等級的螢光成像精度。螢光奈米鑽石在受激發射損耗顯微術，是最佳的螢光標記，因為它不會光漂白（Photobleach）。相對之下，經由高功率的STED雷射光束照射，有機螢光染料或是螢光蛋白是很容易光損傷。螢光奈米鑽石的另一個顯著特徵是，螢光生命週期超過13奈秒，生命週期明顯長於普通的有機螢光染料或是綠色螢光蛋白（Green Fluorescent Protein; 簡稱GFP），以及細胞的自體螢光。藉由時間選通技術，成功地降低了細胞與組織的自體螢光背景訊號，我們應用螢光奈米鑽石作為細胞長時間的追蹤和證實移植的小鼠肺部幹細胞之歸巢和植入的能力。最後，在鑽石內部的氮空缺中心具有一個非常獨特的量子系統，並且可以通過光偵測磁共振技術進行操控，適用於測量環境的變化，例如是溫度改變。使用光偵測磁共振技術，我們實現了高靈敏度的溫度測量，在尺寸為100 奈米螢光鑽石的周圍溫度。以現代生物醫學和生物技術應用而言，所有的實驗結果證實，螢光奈米鑽石在奈米功能顯影劑技術和感測器探測，是最具有潛力而理想之選項。Diamond is an allotrope of carbon. A unique property that distinguishes it from other carbon materials is that diamond is optically transparent and often contains point defects as color centers. Negatively charged nitrogen-vacancy (NV−) defects are the most noteworthy color centers in diamond because it emits far-red fluorescence with high photostability. This unique optical property combined with good biocompatibility makes nanoscale diamonds a promising fluorescent probe for bioimaging, particularly cell tracking studies. Firstly, we measured the efficiency of Forster resonance energy transfer (FRET) with sub-20-nm fluorescent nanodiamonds (FNDs) as the FRET donors and near-infrared dyes as the acceptors. A FRET efficiency of ~7% was found. Next, we built a super-resolution stimulated emission depletion (STED) microscopy system for FNDs and demonstrated the nanoscale precision for fluorescence imaging. FND is an ideal candidate for STED, since it does not photobleach. In contrast, organic dyes or fluorescent proteins are easily photodamaged by the high-power STED laser beam. Another distinct feature of FND is that its fluorescence lifetime is more than 13 ns, significantly longer than that of common organic dyes or green fluorescent proteins (GFPs) as well as cell auto-fluorescence. Using a time-gating technique, which successfully reduces cell and tissue auto-fluorescence background signals, we applied FNDs as long-term cell trackers and demonstrated the homing and engraftment capacity of lung stem cells transplanted in mice. Finally, the NV− center in diamond is a very unique quantum system, and can be manipulated by optical detected magnetic resonance (ODMR), a technique applicable to measure environmental changes such as temperature shifts. With the ODMR technique, we achieved high-sensitivity detection of the surrounding temperature of 100-nm FND particles at the nanoscale. All the experimental results demonstrate that FNDs are ideal candidates for potential applications in modern biomedical science and biotechnologies as nanotechnology-enabled imaging agents and sensors.Contents 口試委員審定書………………………………………………………………………......I Abstract…………………………………………………………………...……………..II 摘要…………………………………………………………………...……………….....III List of Figures…………………………………………………………………...…….VII List of Tables…………………………………………………………………………...XI Chapter 1. Introduction 1.1 Nitrogen-vacancy color centers in diamond…………….…..……...…....1 1.2 Fluorescent nanodiamonds (FNDs)………………..………………….........5 References……………………………………...…………………………………...…….7 Chapter 2. Sub-20-nm Fluorescent Nanodiamonds as Photostable Biolabels and Forster resonance energy transfer (FRET) Donors 2.1 Introduction.……………………………………………….…………..……...…9 2.2 Experimental Section...……………………………………………..…...…...15 2.3 Result and discussion…………………………………………………….…..19 2.4 Conclusion…………………………………………………………..……..……29 References…………....……………………………………………………...…...….…..30 Chapter 3. Superresolution Imaging of Albumin-Conjugated Fluorescent Nanodiamonds in Cells by Stimulated Emission Depletion 3.1 Introduction………………………………………….………….….……...…..33 3.2 Experimental section……………..……………………….…………….…...35 3.3 Result and discussion…………………………………………...…….……..54 3.4 Conclusion……………………………………………………….……….…….59 References……………………...…………………..………………………………...…..60 Chapter 4. Tracking the Engraftment and Regenerative Capabilities of Transplanted Lung Stem Cells using Fluorescent Nanodiamonds 4.1 Introduction………………………………………………………………..……63 4.2 Experimental section…………………………….……………….……………66 4.3 Result and discussion…………………………………...……………..……..75 4.4 Conclusion………………………………………………………………..……..99 References………………………………..………………………………………....…...100 Chapter 5. Nano-Scale Thermometry with Fluorescent Nanodiamonds 5.1 Introduction…………………………………………………………….……..104 5.2 Experimental section………………………………………………………...106 5.3 Result and discussion……………………………………..…………..…….109 5.4 Conclusion………………………………………………………………..……119 References…………………………………………………………….……………........120 Appendix…………………………………………………………………………......…..12