879 resultados para 020603 Quantum Information Computation and Communication
Resumo:
This study was conducted under the auspices of the Subcommittee on Risk Communication and Education of the Committee to Coordinate Environmental Health and Related Programs (CCEHRP) to determine how Public Health Service (PHS) agencies are communicating information about health risk, what factors contributed to effective communication efforts, and what specific principles, strategies, and practices best promote more effective health risk communication outcomes.^ Member agencies of the Subcommittee submitted examples of health risk communication activities or decisions they perceived to be effective and some examples of cases they thought had not been as effective as desired. Of the 10 case studies received, 7 were submitted as examples of effective health risk communication, and 3, as examples of less effective communication.^ Information contained in the 10 case studies describing the respective agencies' health risk communication strategies and practices was compared with EPA's Seven Cardinal Rules of Risk Communication, since similar rules were not found in any PHS agency. EPA's rules are: (1) Accept and involve the public as a legitimate partner. (2) Plan carefully and evaluate your efforts. (3) Listen to the public's specific concerns. (4) Be honest, frank, and open. (5) Coordinate and collaborate with other credible sources. (6) Meet the needs of the media. (7) Speak clearly and with compassion.^ On the basis of case studies analysis, the Subcommittee, in their attempts to design and implement effective health risk communication campaigns, identified a number of areas for improvement among the agencies. First, PHS agencies should consider developing a focus specific to health risk communication (i.e., office or specialty resource). Second, create a set of generally accepted practices and guidelines for effective implementation and evaluation of PHS health risk communication activities and products. Third, organize interagency initiatives aimed at increasing awareness and visibility of health risk communication issues and trends within and between PHS agencies.^ PHS agencies identified some specific implementation strategies the CCEHRP might consider pursuing to address the major recommendations. Implementation strategies common to PHS agencies emerged in the following five areas: (1) program development, (2) building partnerships, (3) developing training, (4) expanding information technologies, and (5) conducting research and evaluation. ^
Resumo:
This issue's Works-In-Progress department has four entries related to the issue's theme, Information and Communication Technologies for Development (ICTD). They are “Sustainable ICT in Agricultural Value Chains”, “Measuring Social Inclusion in Primary Schools”, “An Architecture for Green Mobile Computation”, and “Improving Communication in Resource-Poor Settings”. A fifth entry, “mFeel: An Affective Mobile System”, covers the mFeel mobile system, which combines context awareness with affective and cognitive techniques.
Resumo:
Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID) technology (NFC). The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient?s dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system?s operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials.
Resumo:
Aiming to address requirements concerning integration of services in the context of ?big data?, this paper presents an innovative approach that (i) ensures a flexible, adaptable and scalable information and computation infrastructure, and (ii) exploits the competences of stakeholders and information workers to meaningfully confront information management issues such as information characterization, classification and interpretation, thus incorporating the underlying collective intelligence. Our approach pays much attention to the issues of usability and ease-of-use, not requiring any particular programming expertise from the end users. We report on a series of technical issues concerning the desired flexibility of the proposed integration framework and we provide related recommendations to developers of such solutions. Evaluation results are also discussed.
Resumo:
Secret-key agreement, a well-known problem in cryptography, allows two parties holding correlated sequences to agree on a secret key communicating over a public channel. It is usually divided into three different procedures: advantage distillation, information reconciliation and privacy amplification. The efficiency of each one of these procedures is needed if a positive key rate is to be attained from the legitimate parties? correlated sequences. Quantum key distribution (QKD) allows the two parties to obtain correlated sequences, provided that they have access to an authenticated channel. The new generation of QKD devices is able to work at higher speeds and in noisier or more absorbing environments. This exposes the weaknesses of current information reconciliation protocols, a key component to their performance. Here we present a new protocol based in low-density parity-check (LDPC) codes that presents the advantages of low interactivity, rate adaptability and high efficiency,characteristics that make it highly suitable for next generation QKD devices.
Resumo:
In the first part of this work, we show how certain techniques from quantum information theory can be used in order to obtain very sharp embeddings between noncommutative Lp-spaces. Then, we use these estimates to study the classical capacity with restricted assisted entanglement of the quantum erasure channel and the quantum depolarizing channel. In particular, we exactly compute the capacity of the first one and we show that certain nonmultiplicative results hold for the second one.
Resumo:
This article examines the U.S model of library and information science (LIS) education in light of the changes brought about by information and communication technology. The accepted model of professional preparation in the United States has emphasized graduate education on a Master’s level from LIS programs accredited by the American Library Association (ALA). The authors trace the historical development of this approach and provide an overview of the ALA accreditation process. Furthermore, they examine the strategies of LIS programs in adjusting to the changing information environment, present the debate about the iSchool movement, and discuss the evolution of the core curriculum. In addition, the article explores the relationship between LIS education and the field of practice and presents a practitioner’s perspective on educating library professionals. The authors conclude that the model of advanced professional preparation for librarianship is still relevant in the digital environment, but it requires greater flexibility and close cooperation with the field of practice.
Resumo:
Digital magnetic recording is based on the storage of a bit of information in the orientation of a magnetic system with two stable ground states. Here we address two fundamental problems that arise when this is done on a quantized spin: quantum spin tunneling and backaction of the readout process. We show that fundamental differences exist between integer and semi-integer spins when it comes to both reading and recording classical information in a quantized spin. Our findings imply fundamental limits to the miniaturization of magnetic bits and are relevant to recent experiments where a spin-polarized scanning tunneling microscope reads and records a classical bit in the spin orientation of a single magnetic atom.
Resumo:
Complete and precise characterization of a quantum dynamical process can be achieved via the method of quantum process tomography. Using a source of correlated photons, we have implemented several methods, each investigating a wide range of processes, e.g., unitary, decohering, and polarizing. One of these methods, ancilla-assisted process tomography (AAPT), makes use of an additional ancilla system, and we have theoretically determined the conditions when AAPT is possible. Surprisingly, entanglement is not required. We present data obtained using both separable and entangled input states. The use of entanglement yields superior results, however.
Resumo:
A quantum random walk on the integers exhibits pseudo memory effects, in that its probability distribution after N steps is determined by reshuffling the first N distributions that arise in a classical random walk with the same initial distribution. In a classical walk, entropy increase can be regarded as a consequence of the majorization ordering of successive distributions. The Lorenz curves of successive distributions for a symmetric quantum walk reveal no majorization ordering in general. Nevertheless, entropy can increase, and computer experiments show that it does so on average. Varying the stages at which the quantum coin system is traced out leads to new quantum walks, including a symmetric walk for which majorization ordering is valid but the spreading rate exceeds that of the usual symmetric quantum walk.
Resumo:
We show that the one-way channel formalism of quantum optics has a physical realization in electronic systems. In particular, we show that magnetic edge states form unidirectional quantum channels capable of coherently transporting electronic quantum information. Using the equivalence between one-way photonic channels and magnetic edge states, we adapt a proposal for quantum state transfer to mesoscopic systems using edge states as a quantum channel, and show that it is feasible with reasonable experimental parameters. We discuss how this protocol may be used to transfer information encoded in number, charge, or spin states of quantum dots, so it may prove useful for transferring quantum information between parts of a solid-state quantum computer
Resumo:
We show how the measurement induced model of quantum computation proposed by Raussendorf and Briegel ( 2001, Phys. Rev. Letts., 86, 5188) can be adapted to a nonlinear optical interaction. This optical implementation requires a Kerr nonlinearity, a single photon source, a single photon detector and fast feed forward. Although nondeterministic optical quantum information proposals such as that suggested by KLM ( 2001, Nature, 409, 46) do not require a Kerr nonlinearity they do require complex reconfigurable optical networks. The proposal in this paper has the benefit of a single static optical layout with fixed device parameters, where the algorithm is defined by the final measurement procedure.
Resumo:
We show that interesting multigate circuits can be constructed using a postselected controlled-sign gate that works with a probability (1/3)(n), where n-1 is the number of controlled-sign gates in the circuit, rather than (1/9)(n-1), as would be expected from a sequence of such gates. We suggest some quantum information tasks which could be demonstrated using these circuits, such as parity checking and cluster-state computation.
Resumo:
We present unified, systematic derivations of schemes in the two known measurement-based models of quantum computation. The first model (introduced by Raussendorf and Briegel, [Phys. Rev. Lett. 86, 5188 (2001)]) uses a fixed entangled state, adaptive measurements on single qubits, and feedforward of the measurement results. The second model (proposed by Nielsen, [Phys. Lett. A 308, 96 (2003)] and further simplified by Leung, [Int. J. Quant. Inf. 2, 33 (2004)]) uses adaptive two-qubit measurements that can be applied to arbitrary pairs of qubits, and feedforward of the measurement results. The underlying principle of our derivations is a variant of teleportation introduced by Zhou, Leung, and Chuang, [Phys. Rev. A 62, 052316 (2000)]. Our derivations unify these two measurement-based models of quantum computation and provide significantly simpler schemes.
Resumo:
We consider a universal set of quantum gates encoded within a perturbed decoherence-free subspace of four physical qubits. Using second-order perturbation theory and a measuring device modelled by an infinite set of harmonic oscillators, simply coupled to the system, we show that continuous observation of the coupling agent induces inhibition of the decoherence due to spurious perturbations. We thus advance the idea of protecting or even creating a decoherence-free subspace for processing quantum information.