Showing papers on "Diamond published in 2011"
TL;DR: In this paper, point defects in diamond known as nitrogen-vacancy centres have been shown to be sensitive to minute magnetic fields, even at room temperature, and a demonstration that the spin associated with these defect centres is also sensitive to electric fields holds out the prospect of a sensor that can resolve single spins and single elementary charges at the nanoscale.
Abstract: Point defects in diamond known as nitrogen-vacancy centres have been shown to be sensitive to minute magnetic fields, even at room temperature. A demonstration that the spin associated with these defect centres is also sensitive to electric fields holds out the prospect of a sensor that can resolve, under ambient conditions, single spins and single elementary charges at the nanoscale.
1,027 citations
TL;DR: It is demonstrated that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin.
Abstract: Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical electronic and optical technologies.
669 citations
TL;DR: In this article, the authors demonstrate coupling of the zero-phonon line of individual nitrogen vacancies to the modes of microring resonators fabricated in single-crystal diamond.
Abstract: Integrated quantum photonic technologies are key for future applications in quantum information, ultralow-power opto-electronics and sensing. As individual quantum bits, nitrogen-vacancy centres in diamond are among the most promising solid-state systems identified to date, because of their long-lived electron and nuclear spin coherence, and capability for individual optical initialization, readout and information storage. The major outstanding hurdle lies in interconnecting many nitrogen vacancies for large-scale computation. One of the most promising approaches in this regard is to couple them to optical resonators, which can be further interconnected in a photonic network. Here, we demonstrate coupling of the zero-phonon line of individual nitrogen vacancies to the modes of microring resonators fabricated in single-crystal diamond. Zero-phonon line enhancement by more than a factor of 10 is estimated from lifetime measurements. The devices are fabricated using standard semiconductor techniques and off-the-shelf materials, thus enabling integrated diamond photonics.
452 citations
TL;DR: In this article, a process for the fabrication of high-quality, spatially isolated nano-diamonds on iridium via microwave-plasma-assisted chemical vapour deposition (CVD) growth was introduced.
Abstract: We introduce a process for the fabrication of high-quality, spatially isolated nano-diamonds on iridium via microwave-plasma-assisted chemical vapour deposition (CVD) growth. We perform spectroscopy of single silicon-vacancy (SiV) centres produced during the growth of the nano-diamonds. The colour centres exhibit extraordinary narrow zero-phonon-lines down to 0.7 nm at room temperature. Single photon count rates up to 4.8 Mcps at saturation make these SiV centres the brightest diamond-based single photon sources to date. We measure for the first time the fine structure of a single SiV centre, thus confirming the atomic composition of the investigated colour centres.
395 citations
TL;DR: The calculations on geometrical, vibrational, and electronic properties reveal that T-carbon, with a considerable structural stability and a much lower density 1.50 g/cm3, is a semiconductor with a direct band gap about 3.0 eV, and has a Vickers hardness 61.1 GPa lower than diamond but comparable with cubic boron nitride.
Abstract: A structurally stable crystalline carbon allotrope is predicted by means of the first-principles calculations. This allotrope can be derived by substituting each atom in diamond with a carbon tetrahedron, and possesses the same space group $Fd\overline{3}m$ as diamond, which is thus coined as T-carbon. The calculations on geometrical, vibrational, and electronic properties reveal that T-carbon, with a considerable structural stability and a much lower density $1.50\text{ }\text{ }\mathrm{g}/{\mathrm{cm}}^{3}$, is a semiconductor with a direct band gap about 3.0 eV, and has a Vickers hardness 61.1 GPa lower than diamond but comparable with cubic boron nitride. Such a form of carbon, once obtained, would have wide applications in photocatalysis, adsoption, hydrogen storage, and aerospace materials.
394 citations
TL;DR: In this paper, it was shown that the spin state of an electron localized to the nitrogen-vacancy centre can be transferred to the nuclear spin, where it can be stored until needed.
Abstract: A nitrogen impurity in diamond—where two of the carbon atoms are replaced by a nitrogen atom and a vacant lattice site—is seen as a valuable qubit. The spin of an electron localized to the nitrogen-vacancy centre is commonly used for processing. Researchers now show that this electron spin state can be transferred to the nitrogen nuclear spin, where it can be stored until needed.
352 citations
TL;DR: In this paper, the effect of surface termination on the charge state of nitrogen-vacancy (NV) centers, which have been ion-implanted a few nanometers below the surface of diamond, was investigated.
Abstract: We investigate the effect of surface termination on the charge state of nitrogen-vacancy (NV) centers, which have been ion-implanted a few nanometers below the surface of diamond. We find that, when changing the surface termination from oxygen to hydrogen, previously stable NV${}^{\ensuremath{-}}$ centers convert into NV${}^{0}$ and, subsequently, into an unknown nonfluorescent state. This effect is found to depend strongly on the implantation dose. Simulations of the electronic band structure confirm the disappearance of NV${}^{\ensuremath{-}}$ in the vicinity of the hydrogen-terminated surface. The band bending, which induces a $p$-type surface conductive layer, leads to a depletion of electrons in the nitrogen-vacancies close to the surface. Therefore, hydrogen surface termination provides a chemical way to control the charge state of nitrogen-vacancy centers in diamond. Furthermore, it opens the way to electrostatic control of the charge state with the use of an external gate electrode.
317 citations
TL;DR: In this paper, a single quantum system comprising a nitrogen-vacancy in diamond is coupled to a nanowire cantilever and magnetic fields are used to couple the spin and the oscillator enabling read-out of the nanometre-scale motion.
Abstract: A single quantum system comprising a nitrogen-vacancy in diamond is now coupled to a nanowire cantilever. Magnetic fields can then couple the nitrogen-vacancy spin and the oscillator enabling read-out of the nanometre-scale motion.
315 citations
TL;DR: In this article, the authors demonstrate a method of imaging spatially varying magnetic fields using a thin layer of nitrogen-vacancy (NV) centers at the surface of a diamond chip.
Abstract: We demonstrate a method of imaging spatially varying magnetic fields using a thin layer of nitrogen-vacancy (NV) centers at the surface of a diamond chip. Fluorescence emitted by the two-dimensional NV ensemble is detected by a CCD array, from which a vector magnetic field pattern is reconstructed. As a demonstration, ac current is passed through wires placed on the diamond chip surface, and the resulting ac magnetic field patterns are imaged using an echo-based technique with sub-micron resolution over a 140µm◊140µm field of view, giving single-pixel sensitivity 100nT/ p Hz. We discuss ongoing efforts to further improve the sensitivity, as well as potential bioimaging applications such as real-time imaging of activity in functional, cultured networks of neurons.
296 citations
TL;DR: It is demonstrated that the large lattice distortions that accompany the formation of diamond nuclei inhibit the phase transition at low pressure, and direct it towards the hexagonal diamond phase at higher pressure.
Abstract: Graphite remains stable at pressures higher than those of its equilibrium coexistence with diamond This has proved hard to explain, owing to the difficulty in simulating the transition with accuracy Ab initio calculations using a trained neural-network potential now show that the stability of graphite and the direct transformation of graphite to diamond can be accounted for by a nucleation mechanism
290 citations
TL;DR: In this article, the authors identify an orthorhombic carbon polymorph in Pnma symmetry that has the lowest enthalpy among proposed cold-compressed graphite phases.
Abstract: We identify by ab initio calculations an orthorhombic carbon polymorph in Pnma symmetry that has the lowest enthalpy among proposed cold-compressed graphite phases. This new phase contains alternating zigzag and armchair buckled carbon sheets transformed via a one-layer by three-layer slip mechanism. It has a wide indirect band gap and a large bulk modulus that are comparable to those of diamond. Its simulated x-ray diffraction pattern best matches the experimental data. Pressure plays a key role in lowering the kinetic barrier during the phase conversion process. These results provide a comprehensive understanding and an excellent account for experimental findings.
TL;DR: Here, molecular dynamics is used to show that polished diamond undergoes an sp(3)-sp(2) order-disorder transition resulting in an amorphous adlayer with a growth rate that strongly depends on surface orientation and sliding direction, in excellent correlation with experimental wear rates.
Abstract: Diamond is the hardest material on Earth. Nevertheless, polishing diamond is possible with a process that has remained unaltered for centuries and is still used for jewellery and coatings: the diamond is pressed against a rotating disc with embedded diamond grit. When polishing polycrystalline diamond, surface topographies become non-uniform because wear rates depend on crystal orientations. This anisotropy is not fully understood and impedes diamond's widespread use in applications that require planar polycrystalline films, ranging from cutting tools to confinement fusion. Here, we use molecular dynamics to show that polished diamond undergoes an sp(3)-sp(2) order-disorder transition resulting in an amorphous adlayer with a growth rate that strongly depends on surface orientation and sliding direction, in excellent correlation with experimental wear rates. This anisotropy originates in mechanically steered dissociation of individual crystal bonds. Similarly to other planarization processes, the diamond surface is chemically activated by mechanical means. Final removal of the amorphous interlayer proceeds either mechanically or through etching by ambient oxygen.
01 May 2011
TL;DR: The controlled coupling of a single nitrogen-vacancy center to a surface plasmon mode propagating along a chemically grown silver nanowire (NW) and directly compare the photon emission properties before and after the coupling is reported.
Abstract: Dipole emitters are expected to efficiently couple to the plasmonic mode propagating along a cylindrically shaped metallic nano-structure [1]. Such a strongly coupled system could serve as a fundamental building block for a single photon source on demand and a device enabling strong non-linear interaction at the level of a few photons [2]. In our contribution we demonstrate the controlled coupling of a single nitrogen vacancy (NV) center in a diamond nano-crystal to a nanowire made of silver. This is in contrast to previous realizations, where the nanowire - dipole system was assembled randomly [3,4]. Ultimate control over the relative nanowire diamond nano-crystal position is achieved by using an atomic force microscope (AFM) in contact mode operation.
TL;DR: In this paper, a method for predicting the hardest crystal structures in a given chemical system was developed based on the evolutionary algorithm USPEX (Universal Structure Prediction: Evolutionary Xtallography) and electronegativity-based hardness model.
Abstract: We have developed a method for prediction of the hardest crystal structures in a given chemical system. It is based on the evolutionary algorithm USPEX (Universal Structure Prediction: Evolutionary Xtallography) and electronegativity-based hardness model that we have augmented with bond-valence model and graph theory. These extensions enable correct description of the hardness of layered, molecular, and low-symmetry crystal structures. Applying this method to C and TiO2, we have (i) obtained a number of low-energy carbon structures with hardness slightly lower than diamond and (ii) proved that TiO2 in any of its possible polymorphs cannot be the hardest oxide, its hardness being below 17 GPa. DOI: 10.1103/PhysRevB.84.092103
TL;DR: In this paper, the authors used a remote plasma enhancement chemical vapor deposition (r-PECVD) system at relatively low temperatures, enabling the deposition of graphene films up to 4-inch wafer scale.
Abstract: We have developed a new method to grow uniform graphene films directly on various substrates, such as insulators, semiconductors, and even metals, without using any catalyst. The growth was carried out using a remote plasma enhancement chemical vapor deposition (r-PECVD) system at relatively low temperatures, enabling the deposition of graphene films up to 4-inch wafer scale. Scanning tunneling microscopy (STM) confirmed that the films are made up of nanocrystalline graphene particles of tens of nanometers in lateral size. The growth mechanism for the nanographene is analogous to that for diamond grown by PECVD methods, in spite of sp2 carbon atoms being formed in the case of graphene rather than sp3 carbon atoms as in diamond. This growth approach is simple, low-cost, and scalable, and might have potential applications in fields such as thin film resistors, gas sensors, electrode materials, and transparent conductive films.
Journal Article•
TL;DR: Measurements of NV center coherence with on-chip coplanar waveguides suggest a pathway for incorporating this scalable nanofabrication technique in future quantum applications.
TL;DR: In this article, a high thermal conductivity of 493 Wm−m−1 K−1 was achieved in the Cu/Ti-coated diamond composites, attributed to the 285nm thick Ti coating.
TL;DR: In this article, a new method is proposed to strengthen interfacial binding between diamond and Cu by coating strong carbide-forming elements, e.g., Ti or Cr on the surface of the diamond through vacuum micro-deposition.
TL;DR: In this article, Tungsten coatings with thickness of 5-500nm are applied onto plane-faced synthetic diamonds with particle sizes of about 430 and 180μm, and the effects of coating composition, thickness and roughness, as well as of impurities, on wettability during the metal impregnation process and on the thermal conductivity (TC) of the composites are considered.
Abstract: Tungsten coatings with thickness of 5–500 nm are applied onto plane-faced synthetic diamonds with particle sizes of about 430 and 180 μm. The composition and structure of the coatings are investigated using scanning electron microscopy, X-ray spectral analysis, X-ray diffraction, and atomic force microscopy. The composition of the coatings varies within the range W–W2C–WC. The average roughness, R
a, of the coatings’ surfaces (20–100 nm) increases with the weight–average thickness of the coating. Composites with a thermal conductivity (TC) as high as 900 W m−1 K−1 are obtained by spontaneous infiltration, without the aid of pressure, using the coated diamond grains as a filler, and copper or silver as a binder. The optimal coating thickness for producing a composite with maximal TC is 100–250 nm. For this thickness the heat conductance of coatings as a filler/matrix interface is calculated as G = (2–10) × 107 W m−2 K−1. The effects of coating composition, thickness and roughness, as well as of impurities, on wettability during the metal impregnation process and on the TC of the composites are considered.
TL;DR: Magnetic resonance and fluorescence spectra of nitrogen-vacancy (NV) color centers ensemble in high purity diamond sample were measured, with temperature ranging from 5.6'K to 295'K as mentioned in this paper.
Abstract: Magnetic resonance and fluorescence spectra of nitrogen-vacancy (NV) color centers ensemble in high purity diamond sample were measured, with temperature ranging from 5.6 K to 295 K. Both microwave and optical transition energies have similar nonlinear temperature dependent changes, which might mainly originate from the local thermal expansion. As the frequency shifts will reduce the fidelity of resonant quantum control, the present results demonstrate the necessity of taking temperature fluctuation into consideration. For temperature below 100 K, the transition energies show tendencies to be constant, which indicate higher stability and performance in applications with NV centers.
Journal Article•
TL;DR: Milburn et al. as mentioned in this paper demonstrated dispersive, single-spin coupling to light for both nondestructive spin measurement, through the Faraday effect, and coherent spin manipulation, through optical Stark effect.
Abstract: Dressing-Up Diamond Defects The spin states of nitrogen vacancy defects in diamond are being explored as information carriers and memories in quantum information systems. Their long lifetimes, fast manipulation rates, and the ability to couple them to adjacent electronic and nuclear spins provide the necessary properties for implementation in solid-state quantum networks. To date, however, the readout of the spin state via photoluminescence, either directly or indirectly, results in the destruction of the spin state. Buckley et al. (p. 1212, published online 14 October; see the Perspective by Milburn) have formed a light-matter hybrid state in which the spin interacts with laser light to form a polariton state. This hybrid state can be optically probed to produce a nondestructive measurement and manipulation technique for the spin state of the nitrogen-vacancy center. Optical pulses were used to nondestructively probe and manipulate the spin state of nitrogen vacancy defects in diamond. The exceptional spin coherence of nitrogen-vacancy centers in diamond motivates their function in emerging quantum technologies. Traditionally, the spin state of individual centers is measured optically and destructively. We demonstrate dispersive, single-spin coupling to light for both nondestructive spin measurement, through the Faraday effect, and coherent spin manipulation, through the optical Stark effect. These interactions can enable the coherent exchange of quantum information between single nitrogen-vacancy spins and light, facilitating coherent measurement, control, and entanglement that is scalable over large distances.
22 Jul 2011
TL;DR: The WILEY SERIES on ELECTROCATALYSIS and ELECTROCHEMISTRY as discussed by the authors presents an overview of the history and current status of the field of diamond technology.
Abstract: Preface. PREFACE TO THE WILEY SERIES ON ELECTROCATALYSIS AND ELECTROCHEMISTRY. List of Contributors. Part I. Synthesis of Diamond Films. 1. Electrochemistry on Diamond: History and Current Status (John C. Angus). 2. Synthesis of Diamond Films (Vadali V. S. S. Srikanth and Xin Jiang). 3. Types of Conducting Diamond Materials and their Properties (Marco A. Quiroz and Erick R. Bandala). Part II. Electrochemistry of Diamond Films. 4. Electrochemistry of Diamond (Yuri Pleskov). 5. Applications of Polycrystalline and Modified Functional Diamond Electrodes (Yasuaki Einaga and Akira Fujishima). 6. Diamond Ultramicroelectrodes and Nanostructured Electrodes (Katherine B. Holt). Part III. Electroanalytical Applications. 7. Electroanalytical Applications of Diamond Films (Weena Siangproh, Amara Apilux, Pimkwan Chantarateepra and Orawon Chailapakul). 8. Cathodic Pretreatment of Boron-Doped Diamond Electrodes and Their Use in Electroanalysis (Leonardo S. Andrade, Giancarlo R. Salazar-Banda, Romeu C. Rocha-Filho and Orlando Fatibello-Filho). Part IV. Industrial Applications. 9. Use of Boron-Doped Diamond Electrode in Electrochemical Generation and Applications of Ferrate (Virender K. Sharma, Enric Brillas, Ignasi Sires and Karel Bouzek). 10. Electrochemical Oxidation of Organic Compounds Induced by Electro-generated Free Hydroxyl Radicals on BDD Electrode (Agnieszka Kapalka, Helmut Baltruschat and Christos Comninellis). 11. Modeling of Electrochemical Process for Water Treatment using Diamond Films (Onofrio Scialdone). 12. Production of Strong Oxidizing Substances with BDD Anodes (Ana Sanchez-Carretero, Cristina Saez, Pablo Canizares, and Manuel A. Rodrigo). 13. Ozone Generation Using Boron Doped Diamond Electrodes (Yunny Meas, Luis A. Godinez and Erika Bustos). 14. Application of Synthetic Diamond Films to Electro-Oxidation Processes (Marco Panizza). 15. Fabrication and Application of Ti/BDD for Wastewater Treatment (Xueming Chen and Guohua Chen). 16. Application of Diamond Films to Water Disinfection (Jessica H. Bezerra Rocha and Carlos A. Martinez-Huitle). 17. Fenton-Electrochemical Treatment of Wastewaters for the Oxidation of Organic Pollutants using BDD (Enric Brillas). 18. Electrochemical Energy Storage and Energy Conversion Systems with Diamond Films (Juan M. Peralta-Hernandez, Aracely Hernandez-Ramirez, Jose L. Guzman-Mar, Luis Hinojosa-Reyes, Giancarlo R. Salazar-Banda and Carlos A. Martinez-Huitle). 19. Use of Diamond Films in Organic Electrosynthesis (Siegfried R. Waldvogel, Axel Kirste and Stamo Mentizi). Part V. Bioelectrochemical Applications. 20. Diamond Sensors for Neurochemistry (Bhavik Anil Patel). 21. DNA Modified Diamond Films (Nianjun Yang and Christoph E. Nebel). Index.
TL;DR: In this paper, the most common process for diamond growth is the chemical vapor deposition (CVD), starting from the first publications until the latest results today, a range of different developments can be seen.
TL;DR: This work demonstrates precise control over the zero-phonon optical transition energies of individual nitrogen-vacancy centers in diamond by applying multiaxis electric fields, via the dc Stark effect, to facilitate the integration of NV-center spins within photonic networks.
Abstract: We demonstrate precise control over the zero-phonon optical transition energies of individual nitrogen-vacancy (NV) centers in diamond by applying multiaxis electric fields, via the dc Stark effect The Stark shifts display surprising asymmetries that we attribute to an enhancement and rectification of the local electric field by photoionized charge traps in the diamond Using this effect, we tune the excited-state orbitals of strained NV centers to degeneracy and vary the resulting degenerate optical transition frequency by >10 GHz, a scale comparable to the inhomogeneous frequency distribution This technique will facilitate the integration of NV-center spins within photonic networks
TL;DR: Experimental and theoretical evidence for compression-induced diamondization of few-layer graphene is reported and electric force microscopy measurements reveal a compression- induced charging inhibition of bilayer and multilayer graphene.
Abstract: Experimental and theoretical evidence for compression-induced diamondization of few-layer graphene is reported. Ab initio calculations predict that hydroxyl groups stabilize the sp(3) hybridization of the two topmost carbon layers, creating a single layer of hydroxylated diamond, or diamondol, when graphene layers are compressed in the presence of water. Electric force microscopy measurements reveal a compression- induced charging inhibition of bilayer and multilayer graphene.
TL;DR: This work demonstrates the first nanofocusing of hard XFEL pulses, and develops diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser.
Abstract: A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×1017 W/cm2 was obtained at 70 fs pulse length.
TL;DR: The chemical reactivity of fully hydrogenated High Pressure High Temperature (HPHT) nanodiamonds (H-NDs) towards grafting is reported, suggesting that C-H related surface properties remain dominant even on particles at the nanoscale.
Abstract: Hydrogen terminations (C-H) confer to diamond layers specific surface properties such as a negative electron affinity and a superficial conductive layer, opening the way to specific functionalization routes. For example, efficient covalent bonding of diazonium salts or of alkene moieties can be performed on hydrogenated diamond thin films, owing to electronic exchanges at the interface. Here, we report on the chemical reactivity of fully hydrogenated High Pressure High Temperature (HPHT) nanodiamonds (H-NDs) towards such grafting, with respect to the reactivity of as-received NDs. Chemical characterizations such as FTIR, XPS analysis and Zeta potential measurements reveal a clear selectivity of such couplings on H-NDs, suggesting that C-H related surface properties remain dominant even on particles at the nanoscale. These results on hydrogenated NDs open up the route to a broad range of new functionalizations for innovative NDs applications development.
TL;DR: In this article, double electron-electron resonance (DEM) was used to study the properties of diamond surface spins and their effect on the sensitivity of a single nitrogen-vacancy (NV) center to sense individual and ensembles of electron spins placed outside the diamond lattice.
Abstract: A single nitrogen-vacancy (NV) center is used to sense individual, as well as small ensembles of, electron spins placed outside the diamond lattice. Applying double electron–electron resonance techniques, we were able to observe Rabi nutations of these external spins as well as the coupling strength between the external spins and the NV sensor, via modulations and accelerated decay of the NV spin echo. Echo modulation frequencies as large as 600 kHz have been observed, being equivalent to a few nanometers distance between the NV and an unpaired electron spin. Upon surface modification, the coupling disappears, suggesting the spins to be localized at surface defects. The present study is important for understanding the properties of diamond surface spins so that their effects on NV sensors can eventually be mitigated. This would enable potential applications such as the imaging and tracking of single atoms and molecules in living cells or the use of NVs on scanning probe tips to entangle remote spins for scalable room temperature quantum computers.
TL;DR: In this paper, the authors search for possible superdense carbon allotropes, and find three structures (hP3, tI12, and tP12) that have significantly greater density.
Abstract: A). Searching for possible superdense carbon allotropes, we have found three structures (hP3, tI12, and tP12) that have significantly greater density. The hP3 and tP12 phases have strong analogy with two polymorphs of silica (β-quartz and keatite), while the tI12 phase is related to the high-pressure SiS2 polymorph. Furthermore, we found a collection of other superdense structures based on the motifs of the aforementioned structures, but with different ways of packing carbon tetrahedra, and among these the hP3 and tI12 structures are the densest. At ambient conditions, the hP3 phase is a semiconductor with the GW band gap of 3.0 eV, tI12 is an insulator with the band gap of 5.5 eV, while tP12 is an insulator, the band gap of which is remarkably high (7.3 eV), making it the widest-gap carbon allotrope. These allotropes are metastable and have comparable to diamond or slightly higher bulk moduli; their Vickers hardnesses are calculated to be 87.6 GPa for hP3, 87.2 GPa for tI12, and 88.3 GPa for tP12, respectively, thus making these allotropes nearly as hard as diamond (for which the same model gives the hardness of 94.3 GPa). Superdense carbon allotropes are predicted to have remarkably high refractive indices and strong dispersion of light.