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Bunching and antibunching in four wave mixing NV center in diamond
摘要： The determination of classical and quantum states through photon bunching and anti-bunching like phenomena may have potential applications in quantum information processing and long-distance quantum communications. We report the photon bunching and multi anti-bunching like phenomena by generating multi-order ?uorescence and four-wave mixing (FWM) at room temperature using the Nitrogen-vacancy (NV) center in diamond. We have implied FWM process to demonstrate the interference pattern emerging from NV of nano-crystals in classical, nonclassical and intermediate (classical and nonclassical) regimes. Intersystem crossing is controlled by the ?uence of incident beams. The interference pattern from dominant ionization of NV- to NVo and NVo to NV- suggests the bunching and anti-bunching like phenomena of photons, respectively.
关键词： antibunching,quantum information processing,quantum communications,diamond,four-wave mixing,photon bunching,NV center
更新于2025-09-10 09:29:36
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Joint measurability of quantum effects and the matrix diamond
摘要： In this work, we investigate the joint measurability of quantum effects and connect it to the study of free spectrahedra. Free spectrahedra typically arise as matricial relaxations of linear matrix inequalities. An example of a free spectrahedron is the matrix diamond, which is a matricial relaxation of the (cid:96)1-ball. We find that joint measurability of binary positive operator valued measures is equivalent to the inclusion of the matrix diamond into the free spectrahedron defined by the effects under study. This connection allows us to use results about inclusion constants from free spectrahedra to quantify the degree of incompatibility of quantum measurements. In particular, we completely characterize the case in which the dimension is exponential in the number of measurements. Conversely, we use techniques from quantum information theory to obtain new results on spectrahedral inclusion for the matrix diamond.
关键词： matrix diamond,quantum measurements,joint measurability,quantum effects,free spectrahedra
更新于2025-09-10 09:29:36
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On-machine texturing of PCD micro-tools for dry micro-slot grinding of BK7 glass
摘要： While using diamond micro-tools for micro-grinding, tool re-clamping errors and low chip removal space from machining zone are the primary factors which cause large vibrations, higher grinding forces and poor surface quality. On-machine tool preparation and tool texturing prior to micro-grinding can reduce tool re-clamping error. It can further help to reduce the tool-workpiece contact area along with enhanced chip removal from the machining zone speci?cally essential during dry micro-grinding as usage of the cutting ?uid should be minimized or completely avoided for environmental aspects. In this study, end faces of polycrystalline diamond (PCD) micro-tools have been on-machine textured using micro electro-discharge machining (micro-EDM) process. Four types of textured tools are envisaged viz. tool with one micro-cavity at the center of the end face (T2), one micro-groove along the end face diameter (T3), two intersecting micro-grooves at the end face (T4) and four intersecting micro-grooves at the end face (T5). A new term “contact area ratio” is de?ned to explain the texture dimension on the end face of the micro-grinding tools. Performances of di?erent micro-textured tools (T2, T3, T4 and T5) with respect to a normal commercial tool (T1) in terms of grinding force, surface roughness and micro-slot quality are investigated for micro-slot grinding of BK7 glass. It is observed that micro-textured micro-grinding tool e?ciently serves the purpose of provisional chip collection in passive grinding areas of the tool whereas chip adhesion or wear on the active grinding areas signi?cantly gets reduced as compared to un-textured tools. Maximum reductions in the x and y direction forces are observed with tool type T5 compared to all other tool types. Reduction in z direction force is comparable for both tool types T2 and T3. Average surface roughness decreased from tool type T1 to type T2, T3 and up to tool type T4 whereas it again increased for tool type T5. The current study shows that textured micro-grinding tools are capable of reducing high normal forces, surface roughness and material dragging which are major concerns during micro-grinding with ?at-end poly-crystalline diamond tools.
关键词： Polycrystalline diamond tool,Micro-texture,Micro-grinding,BK7 glass,Surface roughness,Grinding force,Micro-EDM
更新于2025-09-09 09:28:46
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Spin properties of NV centers in high-pressure, high-temperature grown diamond
摘要： The sensitivity of magnetic and electric field sensors based on nitrogen-vacancy (NV) center in diamond strongly depends on the available concentration of NV and their coherence properties. Achieving high coherence times simultaneously with high concentration is a challenging experimental task. Here, we demonstrate that by using a temperature gradient method of high-pressure, high-temperature growing technique, one can achieve nearly maximally possible dephasing T2* times, limited only by carbon nuclear spins at low nitrogen concentrations or nitrogen electron spin at high nitrogen concentrations. Hahn-echo T2 coherence times were also investigated and found to demonstrate reasonable values. Thus, the high-pressure, high-temperature technique is a strong contender to the popular chemical vapor deposition method in the development of high-sensitivity, diamond-based sensors.
关键词： carbon nuclear spins,diamond-based sensors,NV centers
更新于2025-09-09 09:28:46
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STRUCTURING OF DIAMOND FILMS USING MICROSPHERE LITHOGRAPHY
摘要： In this study, the structuring of micro- and nanocrystalline diamond thin films is demonstrated. The diamond films are structured using the technique of microsphere lithography followed by reactive ion etching. Specifically, this paper presents a four-step fabrication process: diamond deposition (microwave plasma assisted chemical vapor deposition), mask preparation (by the standard Langmuir-Blodgett method), mask modification and diamond etching. A self-assembled monolayer of monodisperse polystyrene (PS) microspheres with close-packed ordering is used as the primary template. Then the PS microspheres and the diamond films are processed in capacitively coupled radiofrequency plasma using various plasma chemistries. This fabrication method illustrates the preparation of large arrays of periodic and homogeneous hillock-like structures. The surface morphology of the processed diamond films is characterized by scanning electron microscopy and with the use of an atomic force microscope. The potential applications of these diamond structures in various fields of nanotechnology are also briefly discussed.
关键词： polystyrene microspheres,nanostructuring,scanning electron microscopy,reactive ion etching,diamond thin films
更新于2025-09-09 09:28:46
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Dynamical processes of low-energy carbon ion collision with the graphene supported by diamond
摘要： The dynamical processes of a low-energy carbon ion collision with the graphene sheet supported by diamond at three impact positions are studied by using empirical potential molecular dynamics simulations. The energy transformation and the structural evolution have been studied. Five types of processes are observed: adsorption, hybridization, defects formation in diamond, atom emission and transmission. We find that the irradiation damage is closely related to the incident energy and impact position. In our simulations, as the projectile collides at a graphene atom, it transfers most of its energy to the primary knock-on atom, and defects are created in graphene. When the projectile moves perpendicular towards the center of a C-C bond in the graphene sheet, the energy transferred from the projectile to the atoms associated with the bond increases firstly and then decreases with the increasing incident energy, and the graphene sheet remains two-dimensional crystal structure after collision when the incident energy is larger than 360 eV. While the impact location is the center of a hexagonal ring on the graphene sheet, the energy transferred from the projectile to the atoms of the target ring is very small regardless of how large is the incident energy, and the graphene sheet is able to keep perfect crystal structure when the incident energy is larger than 34 eV.
关键词： diamond,carbon ion collision,graphene,irradiation damage,molecular dynamics simulations
更新于2025-09-09 09:28:46
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X-Ray Thermoluminescence Dosimetry Characterization of Commercially Available CVD Diamond
摘要： High quality commercially available CVD diamonds are being tested in novel clinical high energy photons, hadron therapy, and high energy physics applications. In the present work, the authors report on the thermoluminescence (TL) and dosimetry properties of commercial synthetic CVD diamond sample from Element6, exposed to X-ray irradiation at dose rates of 3.9–120 Gy min?1 from 0.13 to 90 Gy. The TL glow curves are composed of four peaks with maxima at about 104, 150, 210, and 280 °C and activation energies of 0.78, 0.79, 0.81, and 1.0 eV, respectively. The dose response of the area under TL glow curves is linear at doses lower than 0.6 Gy, supralinear between 0.6 and 6 Gy and sublinear at higher doses. The samples exhibited a strong TL fading of the low temperature 104 °C peaks that fades away around 120 min after irradiation, which is accompanied by increasing of the 210 and 280 °C peaks. The measured TL cycle reproducibility was very good, in spite of the fading exhibited by the lower temperature peak, with values of 0.1–3.0% at different dose rates and doses. It is concluded that CVD commercially single crystal electronic grade diamond may be securely used in clinical radiotherapy.
关键词： dosimetry,fading,thermoluminescence,diamond CVD crystal,X-ray irradiation
更新于2025-09-09 09:28:46
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Morphology and Structure Properties of Boron-doped Diamond Films Prepared by Hot Cathode Direct Current Plasma Chemical Vapor Deposition
摘要： Boron-doped diamond (BDD) films were deposited by hot cathode direct current plasma chemical vapor deposition (HCDC-PCVD) according to various mixture ratios of CH4/H2/B(OCH3)3 gas. The Raman performances and surface morphologies of the BDD films were then characterized by Raman spectroscopy and scanning electron microscopy (SEM). Results indicated that the flow rate of B(OCH3)3 had marked effects on the growth characteristics of the produced boron-doped diamond films. The presence and concentration of the doped boron atoms significantly altered both the surface morphologies and structures of the diamond films. With increasing flow rate of B(OCH3)3, the crystal grain surfaces became smooth as visible under SEM. The B-doping levels in these films increased from 1.75 × 1019 cm-3 to a maximum of 2.4 × 1021 cm-3, estimated from the Raman spectra.
关键词： structural properties,boron-doped diamond (BDD) films,hot cathode direct current PCVD (HCDC-PCVD)
更新于2025-09-09 09:28:46
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Perspectives of the Friction Mechanism of Hydrogenated Diamond-Like Carbon Film in Air by Varying Sliding Velocity
摘要： The purpose of the present work is to probe the friction mechanism of hydrogenated diamond-like carbon (H-DLC) ?lm in air by varying sliding velocity (25–1000 mm/s). Friction tests of Al2O3 ball against H-DLC ?lm were conducted with a rotational ball-on-disk tribometer. As the sliding velocity increases, both the friction coef?cient and the surface wear of H-DLC ?lm decrease, reach the minimum values, and then increase in the high sliding velocity region. Based on the observed results, three main friction mechanisms of H-DLC ?lm—namely graphitization mechanism, transfer layer mechanism, and passivation mechanism—are discussed. Raman analysis indicates that the graphitization of worn surface on the H-DLC ?lm has a negligible contribution to the variation of the friction coef?cient and the surface wear. The origin of the sliding velocity dependence is due to the synergistic interaction between the graphitized transfer layer formation and the surface passivation. The present study will not only enrich the understanding of friction mechanism of H-DLC ?lms in air, but will also help to promote their practical engineering applications.
关键词： transfer layer,sliding velocity,surface passivation,diamond-like carbon ?lm,friction mechanism
更新于2025-09-09 09:28:46
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Geometric phase magnetometry using a solid-state spin
摘要： A key challenge of magnetometry lies in the simultaneous optimization of magnetic field sensitivity and maximum field range. In interferometry-based magnetometry, a quantum two-level system acquires a dynamic phase in response to an applied magnetic field. However, due to the 2π periodicity of the phase, increasing the coherent interrogation time to improve sensitivity reduces field range. Here we introduce a route towards both large magnetic field range and high sensitivity via measurements of the geometric phase acquired by a quantum two-level system. We experimentally demonstrate geometric-phase magnetometry using the electronic spin associated with the nitrogen vacancy (NV) color center in diamond. Our approach enables unwrapping of the 2π phase ambiguity, enhancing field range by 400 times. We also find additional sensitivity improvement in the nonadiabatic regime, and study how geometric-phase decoherence depends on adiabaticity. Our results show that the geometric phase can be a versatile tool for quantum sensing applications.
关键词： magnetometry,diamond,geometric phase,nitrogen vacancy,quantum sensing
更新于2025-09-09 09:28:46