54 research outputs found
Near optimal single photon sources in the solid state
Single-photons are key elements of many future quantum technologies, be it
for the realisation of large-scale quantum communication networks for quantum
simulation of chemical and physical processes or for connecting quantum
memories in a quantum computer. Scaling quantum technologies will thus require
efficient, on-demand, sources of highly indistinguishable single-photons.
Semiconductor quantum dots inserted in photonic structures are ultrabright
single photon sources, but the photon indistinguishability is limited by charge
noise induced by nearby surfaces. The current state of the art for
indistinguishability are parametric down conversion single-photon sources, but
they intrinsically generate multiphoton events and hence must be operated at
very low brightness to maintain high single photon purity. To date, no
technology has proven to be capable of providing a source that simultaneously
generates near-unity indistinguishability and pure single photons with high
brightness. Here, we report on such devices made of quantum dots in
electrically controlled cavity structures. We demonstrate on-demand, bright and
ultra-pure single photon generation. Application of an electrical bias on
deterministically fabricated devices is shown to fully cancel charge noise
effects. Under resonant excitation, an indistinguishability of
is evidenced with a . The photon
extraction of and measured brightness of make this source
times brighter than any source of equal quality. This new generation of
sources open the way to a new level of complexity and scalability in optical
quantum manipulation
The usability attributes and evaluation measurements of mobile media AR (augmented reality)
This research aims to develop a tool for creating user-based design interfaces in mobile augmented reality (MAR) education. To develop a design interface evaluation tool, previous literature was examined for key design elements in the educational usage of MAR. The evaluation criteria identified were presence, affordance, and usability. The research used a focus group interview with 7 AR experts to develop a basic usability evaluation checklist, which was submitted to factor analysis for reliability by 122 experts in practice and academia. Based on this checklist, a MAR usability design interface test was conducted with seven fourth-grade elementary students. Then, it conducted follow-up structured interviews and questionnaires. This resulted in 29 questions being developed for the MAR interface design checklist.ope
Mapper of the IGM Spin Temperature (MIST): Instrument Overview
The observation of the global 21 cm signal produced by neutral hydrogen gas
in the intergalactic medium (IGM) during the Dark Ages, Cosmic Dawn, and Epoch
of Reionization requires measurements with extremely well-calibrated wideband
radiometers. We describe the design and characterization of the Mapper of the
IGM Spin Temperature (MIST), which is a new ground-based, single-antenna,
global 21 cm experiment. The design of MIST was guided by the objectives of
avoiding systematics from an antenna ground plane and cables around the
antenna, as well as maximizing the instrument's on-sky efficiency and
portability for operations at remote sites. We have built two MIST instruments,
which observe in the range 25-105 MHz. For the 21 cm signal, this frequency
range approximately corresponds to redshifts 55.5 > z > 12.5, encompassing the
Dark Ages and Cosmic Dawn. The MIST antenna is a horizontal blade dipole of
2.42 m in length, 60 cm in width, and 52 cm in height above the ground. This
antenna operates without a metal ground plane. The instruments run on 12 V
batteries and have a maximum power consumption of 17 W. The batteries and
electronics are contained in a single receiver box located under the antenna.
We present the characterization of the instruments using electromagnetic
simulations and lab measurements. We also show sample sky measurements from
recent observations at remote sites in California, Nevada, and the Canadian
High Arctic. These measurements indicate that the instruments perform as
expected. Detailed analyses of the sky measurements are left for future work.Comment: Comments welcom
Mechanisms and Evolutionary Patterns of Mammalian and Avian Dosage Compensation
A large-scale comparative gene expression study reveals the different ways in which the chromosome-wide gene dosage reductions resulting from sex chromosome differentiation events were compensated during mammalian and avian evolution
Equal opportunities: Do shareable interfaces promote more group participation than single users displays?
Computers designed for single use are often appropriated suboptimally when used by small colocated groups working together. Our research investigates whether shareable interfaces–that are designed for more than one user to inter-act with–can facilitate more equitable participation in colocated group settings compared with single user displays. We present a conceptual framework that
characterizes Shared Information Spaces (SISs) in terms of how they constrain and invite participation using different entry points. An experiment was conducted that compared three different SISs: a physical-digital set-up (least constrained), a multitouch tabletop (medium), and a laptop display (most constrained). Statistical analyses showed there to be little difference in participation levels between the three conditions other than a predictable lack of equity of control over the interface in the laptop condition. However, detailed qualitative analyses revealed more equitable participation took place in the physical-digital condition in terms of verbal utterances over time. Those who spoke the least contributed most to the physical design task. The findings are discussed in relation to the conceptual framework and, more generally, in terms of how to select, design, and combine different display technologies to support collaborative activities
Initial periodontal screening and radiographic findings - A comparison of two methods to evaluate the periodontal situation
Exploiting New Interaction Techniques for Disaster Control Management Using Multitouch-, Tangible- and Pen-Based-Interaction
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