3,739 research outputs found
Experimental demonstration of evanescent coupling from optical fibre tapers to photonic crystal waveguides
Experimental results demonstrating nearly complete mode-selective evanescent coupling to a photonic crystal waveguide from an optical fibre taper are presented. Codirectional coupling with 98% maximum power transfer to a photonic crystal waveguide of length 65 μm and with a coupling bandwidth of 20 nm is realised
Optomechanically induced transparency and cooling in thermally stable diamond microcavities
Diamond cavity optomechanical devices hold great promise for quantum
technology based on coherent coupling between photons, phonons and spins. These
devices benefit from the exceptional physical properties of diamond, including
its low mechanical dissipation and optical absorption. However the nanoscale
dimensions and mechanical isolation of these devices can make them susceptible
to thermo-optic instability when operating at the high intracavity field
strengths needed to realize coherent photon--phonon coupling. In this work, we
overcome these effects through engineering of the device geometry, enabling
operation with large photon numbers in a previously thermally unstable regime
of red-detuning. We demonstrate optomechanically induced transparency with
cooperativity > 1 and normal mode cooling from 300 K to 60 K, and predict that
these device will enable coherent optomechanical manipulation of diamond spin
systems
Conversion of neutral nitrogen-vacancy centers to negatively-charged nitrogen-vacancy centers through selective oxidation
The conversion of neutral nitrogen-vacancy centers to negatively charged
nitrogen-vacancy centers is demonstrated for centers created by ion
implantation and annealing in high-purity diamond. Conversion occurs with
surface exposure to an oxygen atmosphere at 465 C. The spectral properties of
the charge-converted centers are investigated. Charge state control of
nitrogen-vacancy centers close to the diamond surface is an important step
toward the integration of these centers into devices for quantum information
and magnetic sensing applications.Comment: 4 pages, 3 figure
Single-crystal diamond low-dissipation cavity optomechanics
Single-crystal diamond cavity optomechanical devices are a promising example
of a hybrid quantum system: by coupling mechanical resonances to both light and
electron spins, they can enable new ways for photons to control solid state
qubits. However, realizing cavity optomechanical devices from high quality
diamond chips has been an outstanding challenge. Here we demonstrate
single-crystal diamond cavity optomechanical devices that can enable
photon-phonon-spin coupling. Cavity optomechanical coupling to
frequency () mechanical resonances is observed. In room temperature
ambient conditions, these resonances have a record combination of low
dissipation (mechanical quality factor, ) and high
frequency, with sufficient
for room temperature single phonon coherence. The system exhibits high optical
quality factor () resonances at infrared and visible
wavelengths, is nearly sideband resolved, and exhibits optomechanical
cooperativity . The devices' potential for optomechanical control of
diamond electron spins is demonstrated through radiation pressure excitation of
mechanical self-oscillations whose 31 pm amplitude is predicted to provide 0.6
MHz coupling rates to diamond nitrogen vacancy center ground state transitions
(6 Hz / phonon), and stronger coupling rates to excited state
transitions.Comment: 12 pages, 5 figure
NASA/DOD Aerospace Knowledge Diffusion Research Project. Paper 19: Computer and information technology and aerospace knowledge diffusion
To remain a world leader in aerospace, the US must improve and maintain the professional competency of its engineers and scientists, increase the research and development (R&D) knowledge base, improve productivity, and maximize the integration of recent technological developments into the R&D process. How well these objectives are met, and at what cost, depends on a variety of factors, but largely on the ability of US aerospace engineers and scientists to acquire and process the results of federally funded R&D. The Federal Government's commitment to high speed computing and networking systems presupposes that computer and information technology will play a major role in the aerospace knowledge diffusion process. However, we know little about information technology needs, uses, and problems within the aerospace knowledge diffusion process. The use of computer and information technology by US aerospace engineers and scientists in academia, government, and industry is reported
NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 30: The electronic transfer of information and aerospace knowledge diffusion
Increasing reliance on and investment in information technology and electronic networking systems presupposes that computing and information technology will play a major role in the diffusion of aerospace knowledge. Little is known, however, about actual information technology needs, uses, and problems within the aerospace knowledge diffusion process. The authors state that the potential contributions of information technology to increased productivity and competitiveness will be diminished unless empirically derived knowledge regarding the information-seeking behavior of the members of the social system - those who are producing, transferring, and using scientific and technical information - is incorporated into a new technology policy framework. Research into the use of information technology and electronic networks by U.S. aerospace engineers and scientists, collected as part of a research project designed to study aerospace knowledge diffusion, is presented in support of this assertion
NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 31: The information-seeking behavior of engineers
Engineers are an extraordinarily diverse group of professionals, but an attribute common to all engineers is their use of information. Engineering can be conceptualized as an information processing system that must deal with work-related uncertainty through patterns of technical communications. Throughout the process, data, information, and tacit knowledge are being acquired, produced, transferred, and utilized. While acknowledging that other models exist, we have chosen to view the information-seeking behavior of engineers within a conceptual framework of the engineer as an information processor. This article uses the chosen framework to discuss information-seeking behavior of engineers, reviewing selected literature and empirical studies from library and information science, management, communications, and sociology. The article concludes by proposing a research agenda designed to extend our current, limited knowledge of the way engineers process information
Single crystal diamond nanobeam waveguide optomechanics
Optomechanical devices sensitively transduce and actuate motion of
nanomechanical structures using light. Single--crystal diamond promises to
improve the performance of optomechanical devices, while also providing
opportunities to interface nanomechanics with diamond color center spins and
related quantum technologies. Here we demonstrate dissipative
waveguide--optomechanical coupling exceeding 35 GHz/nm to diamond nanobeams
supporting both optical waveguide modes and mechanical resonances, and use this
optomechanical coupling to measure nanobeam displacement with a sensitivity of
fm/ and optical bandwidth nm. The nanobeams are
fabricated from bulk optical grade single--crystal diamond using a scalable
undercut etching process, and support mechanical resonances with quality factor
at room temperature, and in cryogenic
conditions (5K). Mechanical self--oscillations, resulting from interplay
between photothermal and optomechanical effects, are observed with amplitude
exceeding 200 nm for sub-W absorbed optical power, demonstrating the
potential for optomechanical excitation and manipulation of diamond
nanomechanical structures.Comment: Minor changes. Corrected error in units of applied stress in Fig. 1
Nanoscale Torsional Optomechanics
Optomechanical transduction is demonstrated for nanoscale torsional
resonators evanescently coupled to optical microdisk whispering gallery mode
resonators. The on-chip, integrated devices are measured using a fully
fiber-based system, including a tapered and dimpled optical fiber probe. With a
thermomechanically calibrated optomechanical noise floor down to 7 fm/sqrt(Hz),
these devices open the door for a wide range of physical measurements involving
extremely small torques, as little as 4x10^-20 N*m.Comment: 4 pages, 4 figures - Accepted to APL Oct 22nd, 2012. To appear in
February 4th issue - as cover articl
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