Phonon Networks with Silicon-Vacancy Centers in Diamond Waveguides

We propose and analyze a novel realization of a solid-state quantum network, where separated silicon-vacancy centers are coupled via the phonon modes of a quasi-one-dimensional diamond waveguide. In our approach, quantum states encoded in long-lived electronic spin states can be converted into propagating phonon wave packets and be reabsorbed efficiently by a distant defect center. Our analysis shows that under realistic conditions, this approach enables the implementation of high-fidelity, scalable quantum communication protocols within chip-scale spin-qubit networks. Apart from quantum information processing, this setup constitutes a novel waveguide QED platform, where strong-coupling effects between solid-state defects and individual propagating phonons can be explored at the quantum level

Diamond Mirrors for High-Power Lasers

High-power lasers have numerous scientific and industrial applications. Some key areas include laser cutting and welding in manufacturing, directed energy in fusion reactors or defense applications, laser surgery in medicine, and advanced photolithography in the semiconductor industry. These applications require optical components, in particular mirrors, that withstand high optical powers for directing light from the laser to the target. Ordinarily, mirrors are comprised of multilayer coatings of different refractive index and thickness. At high powers, imperfections in these layers lead to absorption of light, resulting in thermal stress and permanent damage to the mirror. Here we design, simulate, fabricate, and demonstrate monolithic and highly reflective dielectric mirrors which operate under high laser powers without damage. The mirrors are realized by etching nanostructures into the surface of single-crystal diamond, a material with exceptional optical and thermal properties. We measure reflectivities of greater than 98% and demonstrate damage-free operation using 10 kW of continuous-wave laser light at 1070 nm, with intensities up to 4.6 MW/cm2. In contrast, at these laser powers, we observe damage to a standard dielectric mirror based on optical coatings. Our results initiate a new category of broadband optics that operate in extreme conditions

Strain engineering of the silicon-vacancy center in diamond

We control the electronic structure of the silicon-vacancy (SiV) color-center in diamond by changing its static strain environment with a nano-electro-mechanical system. This allows deterministic and local tuning of SiV optical and spin transition frequencies over a wide range, an essential step towards multi-qubit networks. In the process, we infer the strain Hamiltonian of the SiV revealing large strain susceptibilities of order 1 PHz/strain for the electronic orbital states. We identify regimes where the spin-orbit interaction results in a large strain suseptibility of order 100 THz/strain for spin transitions, and propose an experiment where the SiV spin is strongly coupled to a nanomechanical resonator

Social media related transit reviews

With the rapid development of web, 2.0, social media has gained tremendous improvement in user-generated content all over the world. Transportation organization raises the economic growth on influencing the well-being of users using social media as a platform, who shares their opinions; access the employment, services, and social connections. Transportation stakeholders not only forecast the ups and downs occurring in the transportation domain but also understand the customer's expectations and needs in terms of quality of services on exploring the reasons for facing dissatisfaction. Transportation-related data in social media has gained significant importance in transportation research.Tweets are accumulated using the Twitter Streaming API from @RailMinIndia. Around 11000 tweets were extracted from the transportation dataset of Twitter through streaming Twitter API @RailMinIndia during 2017 over a period of 30 day’s time frame

Social media related transit reviews

With the rapid development of web, 2.0, social media has gained tremendous improvement in user-generated content all over the world. Transportation organization raises the economic growth on influencing the well-being of users using social media as a platform, who shares their opinions; access the employment, services, and social connections. Transportation stakeholders not only forecast the ups and downs occurring in the transportation domain but also understand the customer's expectations and needs in terms of quality of services on exploring the reasons for facing dissatisfaction. Transportation-related data in social media has gained significant importance in transportation research.Tweets are accumulated using the Twitter Streaming API from @RailMinIndia. Around 11000 tweets were extracted from the transportation dataset of Twitter through streaming Twitter API @RailMinIndia during 2017 over a period of 30 day’s time frame

A multicolor, broadband (5-20 mu m), quaternary-capped InAs/GaAs quantum dot infrared photodetector

An InAs/GaAs quantum dot infrared photodetector with strong, multicolor, broadband (5-20 mu m) photoresponse is reported. Using a combined quaternary In0.21Al0.21Ga0.58As and GaAs capping that relieves strain and maintains strong carrier confinement, we demonstrate a four color infrared response with peaks in the midwave-(5.7 mu m), longwave-(9.0 and 14.5 mu m), and far-(17 mu m) infrared regions. Narrow spectral widths (7% to 9%) are noted at each of these wavelengths including responsivity value similar to 95.3mA/W at 14.5 mu m. Using strain field and multi-band k.p theory, we map specific bound-to-bound and bound-to-quasibound transitions to the longwave and midwave responses, respectively. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773373

Effects of contact space charge on the performance of quantum intersubband photodetectors

Highly non-uniform electric field exists in the active region of quantum intersubband devices, primarily due to the presence of PN junctions forming between heavily doped contact regions and non-intentionally doped barriers. Using a combination of experiments and theoretical simulations, we investigate the effect of this non-uniform internal electric field on the photodetector operation. Three quantum dots-in-a-well (DWELL) photodetectors have been fabricated with top spacer, bottom spacer, and no spacer around the active region, respectively, to demonstrate the effect of the non-uniform field. Drift-diffusion based calculations of the electric field provide further insight into the device operation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4712601

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High quality-factor optical nanocavities in bulk single-crystal diamond

Single-crystal diamond, with its unique optical, mechanical and thermal properties, has emerged as a promising material with applications in classical and quantum optics. However, the lack of heteroepitaxial growth and scalable fabrication techniques remains the major limiting factors preventing more wide-spread development and application of diamond photonics. In this work, we overcome this difficulty by adapting angled-etching techniques, previously developed for realization of diamond nanomechanical resonators, to fabricate racetrack resonators and photonic crystal cavities in bulk single-crystal diamond. Our devices feature large optical quality factors, in excess of 105, and operate over a wide wavelength range, spanning visible and telecom. These newly developed high-Q diamond optical nanocavities open the door for a wealth of applications, ranging from nonlinear optics and chemical sensing, to quantum information processing and cavity optomechanics.Physic