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Malocclusions in the vertical plane are more difficult to treat as compared to the malocclusions in the sagittal plane as they often require multidisciplinary (surgical) approach. Skeletal vertical deficiency and excess causes jaw discrepancies in the sagittal vector too due to rotation of the mandible, thus presenting a complex situation which requires astute treatment planning and implementation. In this article, two cases treated with combined orthodontics and orthognathic surgery to treat skeletal class II malocclusion with vertical deficiency and excess are shown and all details of treatment planning are discussed.

Optical quantum information processing will require highly efficient photonic circuits to connect quantum nodes on-chip and across long distances. This entails the efficient integration of optically addressable qubits into photonic circuits, as well as quantum frequency conversion to the telecommunications band. 4H-silicon carbide (4H-SiC) offers unique potential for on-chip quantum photonics, as it hosts a variety of promising colour centres and has a strong second-order optical nonlinearity. Here, we demonstrate within a single, monolithic platform the strong enhancement of emission from a colour centre and efficient optical frequency conversion. We develop a fabrication process for thin films of 4H-SiC, which are compatible with industry-standard, CMOS nanofabrication. This work provides a viable route towards industry-compatible, scalable colour-centre-based quantum technologies, including the monolithic generation and frequency conversion of quantum light on-chip. Monolithic photonics devices based on SiC are fabricated by a wafer bonding and thinning technique. The strong enhancement of single-photon emission from a colour centre and optical frequency conversion with an efficiency of 360% W−1 are demonstrated.

A transducer of single photons between microwave and optical frequencies can be used to realize quantum communication over optical fiber links between distant superconducting quantum computers. A promising scalable approach to constructing such a transducer is to use ensembles of quantum emitters interacting simultaneously with electromagnetic fields at optical and microwave frequencies. However, inhomogeneous broadening in the transition frequencies of the emitters can be detrimental to this collective action. In this article, we utilise a gradient-based optimization strategy to design the temporal shape of the laser field driving the transduction system to mitigate the effects of inhomogeneous broadening. We study the improvement of transduction efficiencies as a function of inhomogeneous broadening in different single-emitter cooperativity regimes and correlate it with a restoration of superradiance effects in the emitter ensembles. Furthermore, to assess the optimality of our pulse designs, we provide certifiable bounds on the design problem and compare them to the achieved performance., 8 pages, 5 figures; added calculation of upper bounds; added new appendices; expanded the introduction

Optimized process and reduced cost of ownership are important considerations for Chemical Mechanical Planarization. Slurry blending and distribution systems can have a significant impact on Chemical Mechanical Planarization process performance especially for state-of-the-art semiconductor technology nodes. Design of Slurry Delivery Systems plays an important role in slurry blending and distribution but is often overlooked. Improved Slurry Delivery System design can lead to low cost of ownership, yield improvement and higher tool uptime for a fleet of Chemical Mechanical Planarization tools.We highlight some critical aspects of Slurry Delivery System design to improve blending, Slurry Delivery System uptime, real-time analytical parameter monitoring and to reduce slurry agglomeration. We compare Slurry Delivery Systems with and without these design features in order to emphasize the importance of good Slurry Delivery System design.

We use numerical optimization to design the temporal shape of the laser field driving an inhomogeneous ensemble of quantum emitters in order to restore superradiance effects and improve single photon microwave-to-optical transduction efficiencies.

The ability to shape photon emission facilitates strong photon-mediated interactions between disparate physical systems, thereby enabling applications in quantum information processing, simulation and communication. Spectral control in solid state platforms such as color centers, rare earth ions, and quantum dots is particularly attractive for realizing such applications on-chip. Here we propose the use of frequency-modulated optical transitions for spectral engineering of single photon emission. Using a scattering-matrix formalism, we find that a two-level system, when modulated faster than its optical lifetime, can be treated as a single-photon source with a widely reconfigurable photon spectrum that is amenable to standard numerical optimization techniques. To enable the experimental demonstration of this spectral control scheme, we investigate the Stark tuning properties of the silicon vacancy in silicon carbide, a color center with promise for optical quantum information processing technologies. We find that the silicon vacancy possesses excellent spectral stability and tuning characteristics, allowing us to probe its fast modulation regime, observe the theoretically-predicted two-photon correlations, and demonstrate spectral engineering. Our results suggest that frequency modulation is a powerful technique for the generation of new light states with unprecedented control over the spectral and temporal properties of single photons., 9 pages, 6 figures; Supplementary Information

We investigate the degree of indistinguishability of cascaded photons emitted from a three-level quantum ladder system; in our case the biexciton-exciton cascade of semiconductor quantum dots. For the three-level quantum ladder system we theoretically demonstrate that the indistinguishability is inherently limited for both emitted photons and determined by the ratio of the lifetimes of the excited and intermediate states. We experimentally confirm this finding by comparing the quantum interference visibility of noncascaded emission and cascaded emission from the same semiconductor quantum dot. Quantum optical simulations produce very good agreement with the measurements and allow us to explore a large parameter space. Based on our model, we propose photonic structures to optimize the lifetime ratio and overcome the limited indistinguishability of cascaded photon emission from a three-level quantum ladder system.

We demonstrate a computational, optimization-based approach to inverse-design photonic devices meeting desired performance specifications. Several applications range from compact wavelength-demultiplexer devices to quantum optics and chip-scale LIDAR.

Miniaturizing particle accelerators Particle accelerators are usually associated with large national facilities. Because photons are able to impart momentum to electrons, there are also efforts to develop laser-based particle accelerators. Sapra et al. developed an integrated particle accelerator using photonic inverse design methods to optimize the interaction between the light and the electrons. They show that an additional kick of around 0.9 kilo–electron volts (keV) can be given to a bunch of 80-keV electrons along just 30 micrometers of a specially designed channel. Such miniaturized dielectric laser accelerators could open up particle physics to a number of scientific disciplines. Science , this issue p. 79

The miniaturization of current image sensors is largely limited by the volume of the optical elements. Using a sub-wavelength patterned quasi-periodic structure, also known as a metasurface, one can build planar optical elements based on the principle of diffraction. However, it was believed that high refractive index materials are required for metasurface optics. Here, we show that one can employ the design principles of a metasurface even with low contrast materials, such as silicon nitride. We validate our theory by fabricating and experimentally characterizing several silicon nitride based lenses and vortex beam generators . The fabricated lenses achieved beam spots of less than 1 {\mu}m with numerical apertures as high as ~ 0.75. A transmission efficiency of 90% and focusing efficiency of 40% in the visible regime was observed. Our results pave the way towards building low-loss metasurface based optical elements at visible frequencies using low contrast materials., Comment: 6 figures

Quantum emitters in semiconductors, such as quantum dots and color centers, have been used to demonstrate nonclassical light sources with high purity, indistinguishability, and efficiency. Further improvements can be achieved by employing photonics optimization techniques.

We present an analytical model to compute the field scattered from a cloud of finite rough cylinders. The scheme presented in this paper allows the calculation of the ensemble averaged covariance matrix of the scattered field in terms of the correlation function of the cylinder roughness and thus obviates the need for a full-fledged monte-carlo simulation. Using our analytical model, we compare the back-scattered polarisation response of a cloud of rough cylinders to that of a cloud of smooth cylinders — it is found that depending on the cylinder radius and orientation, the surface roughness can have a significant impact on this response. The analytical model presented in this paper allows for an easy and computationally efficient inclusion of cylinder surface roughness into the existing forest models.

We present a gradient-based algorithm to design general 1D grating couplers without any human input from start to finish, including a choice of initial condition. We show that we can reliably design efficient couplers to have multiple functionalities in different geometries, including conventional couplers for single-polarization and single-wavelength operation, polarization-insensitive couplers, and wavelength-demultiplexing couplers. In particular, we design a fiber-to-chip blazed grating with under 0.2 dB insertion loss that requires a single etch to fabricate and no back-reflector., Comment: 8 pages, 7 figures

A large obstacle for realizing quantum photonic logic is the weak optical nonlinearity of available materials, which results in large power consumption. In this paper, we present the theoretical design of all-optical logic with second order ($\chi^{(2)}$) nonlinear bimodal cavities and their networks. Using semiclassical models derived from the Wigner quasi-probability distribution function, we analyze the power consumption and signal-to-noise ratio (SNR) of networks implementing an optical AND gate and an optical latch. Comparison between the second and third order $(\chi^{(3)})$ optical logic reveals that while the $\chi^{(3)}$ design outperforms the $\chi^{(2)}$ design in terms of the SNR for the same input power, employing the $\chi^{(3)}$ nonlinearity necessitates the use of cavities with ultra high quality factors ($Q\sim 10^6$) to achieve gate power consumption comparable to that of the $\chi^{(2)}$ design at significantly smaller quality factors ($Q \sim 10^4$). Using realistic estimates of the $\chi^{(2)}$ and $\chi^{(3)}$ nonlinear susceptibilities of available materials, we show that at achievable quality factors ($Q \sim 10^4$), the $\chi^{(2)}$ design is an order of magnitude more energy efficient than the corresponding $\chi^{(3)}$ design.

We demonstrate integration of cubic SiC (heterostructures and nanostructures) and assemblies of Ge nanoscale islands with Si substrates via a conductive and reflective ZrB2 buffer layer. Hexagonal ZrB2 is grown on cubic Si(111) via a coincidence-misfit mechanism in which the strain is accommodated by edge dislocations along the interface. Ge islands with uniform sizes and strain-free microstructures were grown on ZrB2/Si(111) at 500 °C via thermolysis of Ge2H6, circumventing the strain-driven (Stranski−Krastanov) island formation on Si and associated limitations. Heteroepitaxy between ZrB2(0001) and Ge(111) is obtained via alignment of four lattice rows of Ge with every five rows of ZrB2, (i.e., “magic mismatch”) despite the large difference in lattice constants. Cubic SiC layers with monocrystalline microstructures and atomically abrupt interfaces are grown on ZrB2/Si(111) via single source molecular beam epitaxy of C2(SiH3)2 at 800 °C. Nanoscale SiC islands with perfectly coherent zinc blende structures...

Objective : To investigate the role played by the cranial base flexure in influencing the sagittal and vertical position of the jaws in Indian population. Materials and Methods : Lateral cephalograms of 108 subjects were divided into three categories (Group A: NSAr > 125°, Group B: NSAr-120°-125°, Group C: NSAr < 120°) according to value of NSAr. Measurement of eight angular (SNA, SNB, NPg-FH, ANB, NAPg, SN-GoGn, Y-Axis, ArGo-SN) and seven linear (N-S, S-Ar, Ar-N, Ar-Pt A, Ar-Gn, Wits appraisal, N- Pt A) variables were taken. Results : Pearson correlation coefficient test was used to individually correlate angular and linear variables with NSAr for the whole sample as well as in individual group. Unpaired t -test was used to analyze the difference in the means of all the variables between the three groups. Significance was determined only when the confidence level was P < 0.05. Several parameters (SNB, NAPg, ANB, Y-Axis, GoGn-SN) showed significant positive correlation while others showed negative correlation (SNA, NPg-FH, N-S) with NSAr. Conclusions : This study show cranial base angle has a determinant role in influencing the mandibular position and it also affects both the mandibular plane angle and y-axis. Flattening of the cranial base angle caused a clockwise rotation of the mandible. The jaw relation tends to change from class III to class II, with progressive flattening of the cranial base and vice-versa.

Objectives: The present study aims to clinically compare and evaluate subepithelial connective tissue graft and the GTR based root coverage in treatment of Miller’s Class I gingival recession. Study Design: 30 patients with at least one pair of Miller’s Class I gingival recession were treated either with Subepithelial connective tissue graft (Group A) or Guided tissue regeneration (Group B). Clinical parameters monitored included recession RD, width of keratinized gingiva (KG), probing depth (PD), clinical attachment level (CAL), attached gingiva (AG), residual probing depth (RPD) and % of Root coverage(%RC). Measurements were taken at baseline, three months and six months. A standard surgical procedure was used for both Group A and Group B. Data were recorded and statistical analysis was done for both intergroup and intragroup. Results: At end of six months % RC obtained were 84.47% (Group A) and 81.67% (Group B). Both treatments resulted in statistically significant improvement in clinical parameters. When compared, no statistically significant difference was found between both groups except in RPD, where it was significantly greater in Group A. Conclusions: GTR technique has advantages over subepithelial connective tissue graft for shallow Miller’s Class I defects and this procedure can be used to avoid patient discomfort and reduce treatment time. Key words:Collagen membrane, comparative split mouth study, gingival recession, subepithelial connective tissue graft, guided tissue regeneration (GTR).

In this paper, we present a theoretical analysis of the electromagnetic response of a plasmonic nanowire–spacer–plasmonic film system. The analytical solution presented in this paper is a full-wave solution, which is used to compute the fields scattered by the plasmonic nanostructure system on illumination by a plane electromagnetic wave. The physical structure comprises of an array of plasmonic nanowires made of a plasmonic metal such as gold or silver placed over a plasmonic film of the same material and separated from it by a dielectric spacer such as silica or alumina. Such a nanostructure exhibits a spectrum that is extremely sensitive to various geometric and electromagnetic parameters such as spacer thickness and spacer refractive index, which makes it favourable for various sensing applications such as chemical and biological sensing, strain sensing, position sensing, vibration sensing, and thickness sensing. We report a comparison of our analytical solution with a numerical rigorous coupled wave analysis of the same structure with the plasmonic medium being treated as local in nature.

In this paper we present a theoretical analysis of the electromagnetic response of a plasmonic nanowire-film system. The analytical solution accounts for both the dispersive as well as non-local nature of the plasmonic media. The physical structure comprises of a plasmonic nanowire made of a plasmonic metal such as gold or silver placed over a plasmonic film of the same material. Such a nanostructure exhibits a spectrum that is extremely sensitive to various geometric parameters such as spacer thickness and nanowire radius, which makes it favorable for various sensing applications. The non-locality of the plasmonic medium, which can be captured using the hydrodynamic model, significantly affects the resonant wavelength of this system for structures of small dimensions (~ less than 5 nm gap between the nanowire and the film). We present an analytical method that can be used to predict the effect of non-locality on the resonances of the system. To validate the analytical method, we also report a comparison of our analytical solution with a numerical Finite Difference Time Domain analysis (FDTD) of the same structure with the plasmonic medium being treated as local in nature.

Aim: The purpose of the study was to compare clinical outcomes of laterally positioned pedicle graft (LPPG) and subepithelial connective tissue graft (SCTG) for treatment of Miller's Class I and II gingival recession defects, at the end of 6 months. Materials and Methods: Sixty Miller's Class I or II gingival recession defects (≥3 mm) (n = 30 each) on the labial aspect of anterior teeth were treated by either of the above techniques. Clinical parameters including recession depth (RD), width of keratinized gingiva (WKG), percentage of root coverage (%RC), and complete RC were recorded at baseline and 6 months postoperatively. Data were recorded and statistical analysis was done for both intergroup and intragroup. Statistical Analysis Used: Paired t-test intragroup and Student's t-test intergroup. Results: In LPPG, RD decreased from 4.9 ± 0.99 mm to 1.1 ± 0.3 mm and WKG increased from 0.7 ± 0.87 to 4.5 ± 0.86 mm at 6 months, while in SCTG, RD decreased from 4.67 ± 1.12 mm to 0.46 ± 0.68 mm and WKG increased from 1.1 ± 0.99 to 5.33 ± 0.72 mm at 6 months postoperatively. The values of the soft tissue coverage remained stable for 6 months. Conclusions: Highly significant and effective soft tissue coverage was obtained by both techniques. LPPG resulted in effective soft tissue coverage for isolated deep narrow defects while SCTG in isolated and multiple, deep narrow and wide defects.

Context: In a developing country like India, where expensive cephalometric apparatus is unavailable everywhere, photography assumes importance for diagnostic and treatment planning procedures as it is low cost and less technique sensitive. Aims and Objectives: The aim of this study was to compare and correlate craniofacial measurements from cephalometric radiographs with analogous measurements from standardized facial photographs in the Gujarati population. Materials and Methods: The study was carried out using standardized cephalometric radiographs and photographs of 60 Gujarati subjects (30 males, 30 females). Eight facial landmarks were identified on both the photograph and cephalogram. Five angular and three linear measurements were created from these landmarks and planes. Statistical Analysis Used: The Pearson correlation coefficient was used to estimate the correlations between the photographic and cephalometric variables. The intraclass correlation coefficient (ICC) was estimated to measure the reliability of the repeated tracings. Results: On comparing the cephalometric and photographic variables for the entire sample, positive and significant correlations were found for all the variables studied (r > 0, P < 0.05). The ICCs for all of the angular measurements were higher than those for linear measurements. Conclusion: Photographs may be used reliably for epidemiological purposes, screening, initial consultations and cases where irradiation is contraindicated or needs to be avoided.

We report a unique low-temperature growth method for epitaxial GaN on Si(111) substrates via a ZrB2(0001) buffer layer. The method utilizes the decomposition of a single gas-source precursor (D2GaN3)3 on the substrate surface to form GaN. The film growth process is further promoted by irradiation of ultraviolet light to enhance the growth rate and ordering of the film. The best epitaxial film quality is achieved at a growth temperature of 550°C with a growth rate of 3nm∕min. The films exhibit intense photoluminescence emission at 10K with a single peak at 3.48eV, indicative of band-edge emission for a single-phase hexagonal GaN film. The growth process achieved in this study is compatible with low Si processing temperatures and also enables direct epitaxy of GaN on ZrB2 in contrast to conventional metalorganic chemical vapor deposition based approaches.

We develop a new computational tool and framework for characterizing the scattering of photons by energy-nonconserving Hamiltonians into unidirectional (chiral) waveguides, e.g., with coherent pulsed excitation. We demonstrate this approach for two prototypical quantum systems.

We present the DC Stark tuning of single Silicon Vacancies in SiC. We demonstrate static tuning across 200 GHz, exceeding the inhomogenous broadening, and dynamic tuning on timescales shorter than the optical decay rate.

Sources of non-classical light are of paramount importance for future applications in quantum science and technology such as quantum communication, quantum computation and simulation, quantum sensing and quantum metrology. In this review we discuss the fundamentals and recent progress in the generation of single photons, entangled photon pairs and photonic cluster states using semiconductor quantum dots. Specific fundamentals which are discussed are a detailed quantum description of light, properties of semiconductor quantum dots and light-matter interactions. This includes a framework for the dynamic modelling of non-classical light generation and two-photon interference. Recent progress will be discussed in the generation of non-classical light for off-chip applications as well as implementations for scalable on-chip integration.