320 research outputs found

    High-dimensional decoy-state quantum key distribution over 0.3 km of multicore telecommunication optical fibers

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    Multiplexing is a strategy to augment the transmission capacity of a communication system. It consists of combining multiple signals over the same data channel and it has been very successful in classical communications. However, the use of enhanced channels has only reached limited practicality in quantum communications (QC) as it requires the complex manipulation of quantum systems of higher dimensions. Considerable effort is being made towards QC using high-dimensional quantum systems encoded into the transverse momentum of single photons but, so far, no approach has been proven to be fully compatible with the existing telecommunication infrastructure. Here, we overcome such a technological challenge and demonstrate a stable and secure high-dimensional decoy-state quantum key distribution session over a 0.3 km long multicore optical fiber. The high-dimensional quantum states are defined in terms of the multiple core modes available for the photon transmission over the fiber, and the decoy-state analysis demonstrates that our technique enables a positive secret key generation rate up to 25 km of fiber propagation. Finally, we show how our results build up towards a high-dimensional quantum network composed of free-space and fiber based linksComment: Please see the complementary work arXiv:1610.01812 (2016

    Laser Guide Star Only Adaptive Optics: The Development of Tools and Algorithms for the Determination of Laser Guide Star Tip-Tilt

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    Adaptive Optics (AO) is a technology which corrects for the effects of the atmosphere and so improves the optical quality of ground based astronomical observations. The bright “guide stars” required for correction are not available across the entire sky, so Laser Guide Stars (LGSs) are created. A Natural Guide Star (NGS) is still required to correct for tip-tilt as the LGS encounters turbulence on the uplink path resulting in unpredictable “jitter”, hence limiting corrected sky coverage. In this thesis an original method is proposed and investigated that promises to improve the correction performance for tomographic AO systems using only LGSs, and no NGS, by retrieving the LGS uplink tip-tilt. To investigate the viability of this method, two unique tools have been developed. A new AO simulation has been written in the Python programming language which has been designed to facilitate the rapid development of new AO concepts. It features realistic LGS simulation, ideal to test the method of LGS uplink tip-tilt retrieval. The Durham Real-Time Adaptive Optics Generalised Optical Nexus (DRAGON) is a laboratory AO test bench nearing completion, which features multiple LGS and NGS Wavefront Sensors (WFSs) intended to further improve tomographic AO. A novel method of LGS emulation has been designed, which re-creates focus anisoplanatism, elongation and uplink turbulence. Once complete, DRAGON will be the ideal test bench for further development of LGS uplink tip-tilt retrieval. Performance estimates from simulation of the LGS uplink tip-tilt retrieval method are presented. Performance is improved over tomographic LGS AO systems which do not correct for tip-tilt, giving a modest improvement in image quality over the entire night sky. Correction performance is found to be dependent on the atmospheric turbulence profile. If combined with ground layer adaptive optics, higher correction performance with a very high sky coverage may be achieved

    Organic User Interfaces for InteractiveInterior Design

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    PhD ThesisOrganic User Interfaces (OUIs) are flexible, actuated, digital interfaces characterized by being aesthetically pleasing, physically manipulated and ubiquitously embedded within real-world environments. I postulate that OUIs have specific qualities that offer great potential to realize the vision of smart spaces and ubiquitous computing environments. This thesis makes the case for embedding OUI interaction into architectural spaces, interior elements and decorative artefacts using smart materials – a concept I term ‘OUI Interiors’. Through this thesis, I investigate: 1) What interactive materials and making techniques can be used to design and build OUIs? 2) What OUI decorative artefacts and interior elements can we create? and 3) What can we learn for design by situating OUI interiors? These key research questions form the basis of this PhD and guide all stages of inquiry, analysis, and reporting. Grounded by the state-of-the-art of Interactive Interiors in both research and practice, I developed new techniques of seamlessly embedding smart materials into interior finishing materials via research through design exploration (in the form of a Swatchbook). I also prototyped a number of interactive decorative objects that change shape and colour as a form of organicactuation, in response to seamless soft-sensing (presented in a Product Catalogue). These inspirational artefacts include table-runners, wall-art, pattern-changing wall-tiles, furry-throw, vase, cushion and matching painting, rug, objets d’art and tasselled curtain. Moreover, my situated studies of how people interact idiosyncratically with interactive decorative objects provide insights and reflections on the overall material experience. Through multi-disciplinary collaboration, I have also put these materials in the hands of designers to realize the potentials and limitations of such a paradigm and design three interactive spaces. The results of my research are materialized in a tangible outcome (a Manifesto) exploring design opportunities of OUI Interior Design, and critically considering new aesthetic possibilities

    IST Austria Thesis

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    Fabrication of curved shells plays an important role in modern design, industry, and science. Among their remarkable properties are, for example, aesthetics of organic shapes, ability to evenly distribute loads, or efficient flow separation. They find applications across vast length scales ranging from sky-scraper architecture to microscopic devices. But, at the same time, the design of curved shells and their manufacturing process pose a variety of challenges. In this thesis, they are addressed from several perspectives. In particular, this thesis presents approaches based on the transformation of initially flat sheets into the target curved surfaces. This involves problems of interactive design of shells with nontrivial mechanical constraints, inverse design of complex structural materials, and data-driven modeling of delicate and time-dependent physical properties. At the same time, two newly-developed self-morphing mechanisms targeting flat-to-curved transformation are presented. In architecture, doubly curved surfaces can be realized as cold bent glass panelizations. Originally flat glass panels are bent into frames and remain stressed. This is a cost-efficient fabrication approach compared to hot bending, when glass panels are shaped plastically. However such constructions are prone to breaking during bending, and it is highly nontrivial to navigate the design space, keeping the panels fabricable and aesthetically pleasing at the same time. We introduce an interactive design system for cold bent glass façades, while previously even offline optimization for such scenarios has not been sufficiently developed. Our method is based on a deep learning approach providing quick and high precision estimation of glass panel shape and stress while handling the shape multimodality. Fabrication of smaller objects of scales below 1 m, can also greatly benefit from shaping originally flat sheets. In this respect, we designed new self-morphing shell mechanisms transforming from an initial flat state to a doubly curved state with high precision and detail. Our so-called CurveUps demonstrate the encodement of the geometric information into the shell. Furthermore, we explored the frontiers of programmable materials and showed how temporal information can additionally be encoded into a flat shell. This allows prescribing deformation sequences for doubly curved surfaces and, thus, facilitates self-collision avoidance enabling complex shapes and functionalities otherwise impossible. Both of these methods include inverse design tools keeping the user in the design loop

    Sistemas interativos tangíveis e processos de mediação tecnológica: hipóteses sobre agência, significação e cognição a partir da investigação do MIT Tangible Media Group

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    A presente dissertação toma a investigação em sistemas de interação tangível do MIT Tangible Media Group como objeto, a pretexto da sua inclusão na edição de 2016 do Festival Ars Electronica, sob o tema Radical Atoms: The Alchemists of Our Time. Pretende-se compreender quais os pontos de contato da investigação do grupo com os estudos dos media, de forma a localizar a sua relevância para a programação do festival. O enquadramento nos estudos dos media é feito pela localização de um conjunto de termos-chave no trabalho do grupo, os quais evocam questões afetas à fenomenologia, filosofia da tecnologia e mediação tecnológica. Conclui-se que estes sistemas de interação tangível ativam processos particulares de constituição de agência, significação e cognição. Na ausência de outros materiais que explorem estas relações no contexto do festival, a dissertação apresenta-se assim como complemento à leitura do tema Radical Atoms: The Alchemists of Our Time.This dissertation thesis takes the research of the MIT Tangible Media Group as its object, by occasion of its inclusion in the 2016 edition of Ars Electronica Festival under the theme Radical Atoms: The Alchemists of Our Time. The aim is to understand what are the common points between the group's research and media studies, in order to locate this object's relevance to the festival programming scope. The framing within media studies is done by surveying a set of keywords from the group's research, which evoke topics from phenomenology, philosophy of technology and technological mediation. It's concluded that these tangible interactive systems activate specific processes of agency, signification, and cognition. Given the lack of materials which explore these relationships within the context of the festival, the dissertation presents itself as a supplement to the reading of the Radical Atoms: The Alchemists of Our Time theme

    3G R&D: R&D for the Next Generation of Ground-based Gravitational-wave Detectors

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    To deliver on the promise of next generation gravitational-wave observatories, a sustained and coordinated detector research and development program is required. This report examines in detail the wide range of nearer- and longer-term detector R&D programs needed for next generation GW detectors commensurate with the key science targets presented in "The Next Generation Global Gravitational Wave Observatory: The Science Book", including considerations of site selection and large-scale vacuum infrastructure. The report makes a series of detailed recommendations on the needed advances in detector technology and the timescales needed to achieve those advances. It also identifies areas where larger-scale globally coordinated R&D efforts will be critical to ensuring success while minimizing costs. This report is the third in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors (this report), iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network

    The Boston University Photonics Center annual report 2011-2012

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    This repository item contains an annual report that summarizes activities of the Boston University Photonics Center in the 2011-2012 academic year. The report provides quantitative and descriptive information regarding photonics programs in education, interdisciplinary research, business innovation, and technology development. The Boston University Photonics Center (BUPC) is an interdisciplinary hub for education, research, scholarship, innovation, and technology development associated with practical uses of light.This report summarizes activities of the Boston University Photonics Center during the period July 2011 through June 2012. These activities span the Center’s complementary missions in education, research, technology development, and commercialization. In 2010, the Photonics Center unveiled a five-year strategic plan as part of the University’s comprehensive review of centers and institutes. The Photonics Center continues to show progress on the Photonics Center strategic plan and is growing the Center’s position as an international leader in photonics research. For more information about the strategic plan, read the Photonics Center Strategic Plan section on page 11. In research, Photonics Center faculty published more than 100 journal papers spanning the field of photonics. A number of awards for outstanding achievement in education and research were presented to Photonics Center faculty members, including a Presidential Early Career Award for Scientists and Engineers (PECASE) for Professor Altug, the Boston University Peter Paul Professorship for Professor Han, and a Dean’s Catalyst Award for Professor Joshi. New external grant funding for the 2011-2012 fiscal year totaled $15.8M. For more information on our research activities, read the Research section on page 26. In technology development, the close of FY11 marked the end of the Photonics Center’s decade-long collaboration pipeline technology development with the Army Research Laboratory (ARL). The successful outcomes of that unique partnership include a compelling series of photonics technology prototypes aimed at force protection. Our direct collaboration with Army end users has enabled transformative advanced in sniper detection of bioterror agents, and nuclear threat detection. In the past year, the Photonics Center has expanded the scope of its unique photonic technology development program to include applications in the commercial healthcare sector. For more information on our technology development program and on specific projects, read the Technology Development section on page 52. In education, 17 Photonics Center graduate students received Ph.D. diplomas. Photonics Center faculty taught 29 photonics courses. The Center supported a Research Experiences for Teachers (RET) site in Biophotonic Sensors and Systems for 10 middle school and high school teachers. The Photonics Center sponsored the Herbert J. Berman “Future of Light” Prize at the University’s Science and Engineering Day. Professor Goldberg’s Boston Urban Fellows Project started its seventh year. For more on our education programs, read the Education section on page 64. In commercialization, the Business Innovation Center continues to operate at capacity. Its tenants include 11 technology companies with a majority having core business interests primarily in photonics and life sciences. It houses several companies founded by current and former BU faculty and students and provides students with an opportunity to assist, observe, and learn from start-up companies. For more information about Business Innovation Center activities, read the Business Innovation Center chapter in the Facilities and Equipment section on page 78

    Controlling phonons and photons at the wavelength-scale: silicon photonics meets silicon phononics

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    Radio-frequency communication systems have long used bulk- and surface-acoustic-wave devices supporting ultrasonic mechanical waves to manipulate and sense signals. These devices have greatly improved our ability to process microwaves by interfacing them to orders-of-magnitude slower and lower loss mechanical fields. In parallel, long-distance communications have been dominated by low-loss infrared optical photons. As electrical signal processing and transmission approaches physical limits imposed by energy dissipation, optical links are now being actively considered for mobile and cloud technologies. Thus there is a strong driver for wavelength-scale mechanical wave or "phononic" circuitry fabricated by scalable semiconductor processes. With the advent of these circuits, new micro- and nanostructures that combine electrical, optical and mechanical elements have emerged. In these devices, such as optomechanical waveguides and resonators, optical photons and gigahertz phonons are ideally matched to one another as both have wavelengths on the order of micrometers. The development of phononic circuits has thus emerged as a vibrant field of research pursued for optical signal processing and sensing applications as well as emerging quantum technologies. In this review, we discuss the key physics and figures of merit underpinning this field. We also summarize the state of the art in nanoscale electro- and optomechanical systems with a focus on scalable platforms such as silicon. Finally, we give perspectives on what these new systems may bring and what challenges they face in the coming years. In particular, we believe hybrid electro- and optomechanical devices incorporating highly coherent and compact mechanical elements on a chip have significant untapped potential for electro-optic modulation, quantum microwave-to-optical photon conversion, sensing and microwave signal processing.Comment: 26 pages, 5 figure

    Remixing physical objects through tangible tools

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    Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 147-164).In this document we present new tools for remixing physical objects. These tools allow users to copy, edit and manipulate the properties of one or more objects to create a new physical object. We already have these capabilities using digital media: we can easily mash up videos, music and text. However, it remains difficult to remix physical objects and we cannot access the advantages of digital media, which are nondestructive, scalable and scriptable. We can bridge this gap by both integrating 2D and 3D scanning technology into design tools and employing aordable rapid prototyping technology to materialize these remixed objects. In so doing, we hope to promote copying as a tool for creation. This document presents two tools, CopyCAD and KidCAD, the first designed for makers and crafters, the second for children. CopyCAD is an augmented Computer Numerically Controlled (CNC) milling machine which allows users to copy arbitrary real world object geometry into 2D CAD designs at scale through the use of a camera-projector system. CopyCAD gathers properties from physical objects, sketches and touch interactions directly on a milling machine, allowing novice users to copy parts of real world objects, modify them and create a new physical part. KidCAD is a sculpting interface built on top of a gel-based realtime 2.5D scanner. It allows children to stamp objects into the block of gel, which are scanned in realtime, as if they were stamped into clay. Children can use everyday objects, their hands and tangible tools to design new toys or objects that will be 3D printed. This work enables novice users to easily approach designing physical objects by copying from other objects and sketching new designs. With increased access to such tools we hope that a wide range of people will be empowered to create their own objects, toys, tools and parts.by Sean Follmer.S.M

    Control and Characterization of Line-Addressable Micromirror Arrays

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    This research involved the design and implementation of a complete line-addressable control system for a 32x32 electrostatic piston-actuated micromirror array device. Line addressing reduces the number of control lines from N2 to 2N making it possible to design larger arrays and arrays with smaller element sizes. The system utilizes the electromechanical bi-stability of individual elements to bold arbitrary bi-stable phase patterns. The control system applies pulse width modulated (PWM) signals to the rows and columns of the micromirror array. Three modes of operation were conceived and built into the system. The first was the traditional signal scheme which requires the array to be reset before a new pattern can be applied. The second is an original scheme that allows dynamic switching between bi-stable patterns. The third and final mode applies an effective voltage ramp across the device by operating above mechanical cutoff. Device characterization and control system testing were conducted on predesigned and prefabricated samples from two different foundry processes. Testing results showed that the control system was successfully integrated. However, bi-stable control of individual mirror elements was not successfully demonstrated on samples due to flaws in the device design. A more robust device design which corrects these flaws and increases operational yield is proposed
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