394 research outputs found
Generalized multi-photon quantum interference
Non-classical interference of photons lies at the heart of optical quantum
information processing. This effect is exploited in universal quantum gates as
well as in purpose-built quantum computers that solve the BosonSampling
problem. Although non-classical interference is often associated with perfectly
indistinguishable photons this only represents the degenerate case, hard to
achieve under realistic experimental conditions. Here we exploit tunable
distinguishability to reveal the full spectrum of multi-photon non-classical
interference. This we investigate in theory and experiment by controlling the
delay times of three photons injected into an integrated interferometric
network. We derive the entire coincidence landscape and identify transition
matrix immanants as ideally suited functions to describe the generalized case
of input photons with arbitrary distinguishability. We introduce a compact
description by utilizing a natural basis which decouples the input state from
the interferometric network, thereby providing a useful tool for even larger
photon numbers
Southern Brazilian indigenous populations and the forest: towards an environmental history
Human societies and economies are inextricably linked to oceans and seas. Eight of the worldâs ten largest cities lie adjacent to the ocean (UN Atlas of the Oceans, 2010) and about half of the worldâs population lives within 200 km of a coast â a quarter within 100 km (IPCC, 2007). Oceans and seas provide a range of ecosystem services (including regulating, provisioning and cultural services) that enhance human wellâbeing in numerous ways (Millennium Ecosystem Assessment, 2003, 2005; Hicks, 2011). To the extent that climate change affects ecosystems, it will affect fisheries (as discussed in the preceding chapters of this book) and, by extension, human wellâbeing. In this chapter, we focus on provisioning and cultural services associated with fisheries. Although important, the oceanâs regulating and supporting services, including the fixation of atmospheric carbon, are not further discussed here (for further details, see UNEPâWCMC, 2011). We describe the numerous contributions of marineâbased ecosystems to human wellâbeing and the ways in which climate change and other confounding factors are likely to disrupt relationships between fishers, fisheries and fishing communities. Our three caseâstudies: smallâscale, artisanal and subsistenceâbased fisheries of the western Indian Ocean (WIO), fishing of cultural keystone species in the Torres Strait, and commercial fishing in Australia, serve to highlight the various changes to fisheries likely to be brought about by climate change in three markedly different contexts
Multi-imaging x-ray streak camera for ultrahigh-speed two dimensional x-ray imaging of imploded core plasmas(invited)
Copyright 2004 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Review of Scientific Instruments, 75(10), 3921-3925, 2004 and may be found at http://dx.doi.org/10.1063/1.178924
High-power, kilojoule laser interactions with near-critical density plasma
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98754/1/PhysPlasmas_18_056706.pd
A social-ecological approach to conservation planning: embedding social considerations
Many conservation plans remain unimplemented, in part because of insufficient consideration of the social processes that influence conservation decisions. Complementing social considerations with an integrated understanding of the ecology of a region can result in a more complete conservation approach. We suggest that linking conservation planning to a social-ecological systems (SES) framework can lead to a more thorough understanding of human-environment interactions and more effective integration of social considerations. By characterizing SES as a set of subsystems, and their interactions with each other and with external factors, the SES framework can improve our understanding of the linkages between social and ecological influences on the environment. Using this framework can help to identify socially and ecologically focused conservation actions that will benefit ecosystems and human communities, and assist in the development of more consistent evidence for evaluating conservation actions by comparing conservation case studies
Slowing of Magnetic Reconnection Concurrent with Weakening Plasma Inflows and Increasing Collisionality in Strongly Driven Laser-Plasma Experiments
An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly driven, ÎČ âČ 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-AlfvĂ©nic electron jets (V[subscript jet] ~ 20V[subscript A]) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early in time. The absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly driven regime.United States. Dept. of Energy (Grant DE-NA0001857)University of Rochester. Laboratory for Laser Energetics (Grant 415935-G)National Laser Userâs Facility (Grant DE-NA0002035)University of Rochester. Fusion Science Center (Grant 5-24431
Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging
The significance and nature of ion kinetic effects in D3He-filled, shock-driven inertial confinement
fusion implosions are assessed through measurements of fusion burn profiles. Over this series of
experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number,
NK) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma
conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match
measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured
the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially
resolved measurements of the fusion burn are used to examine kinetic ion transport effects in
greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional
integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison
of measured and simulated burn profiles shows that models including ion transport effects
are able to better match the experimental results. In implosions characterized by large Knudsen
numbers (NK3), the fusion burn profiles predicted by hydrodynamics simulations that exclude
ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally
observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that
includes a model of ion diffusion is able to qualitatively match the measured profile shapes.
Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the
observed trends, though further refinement of the models is needed for a more complete and
quantitative understanding of ion kinetic effects
Implosion hydrodynamics of fast ignition targets
Copyright 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas, 12(5), 056312, 2005 and may be found at http://dx.doi.org/10.1063/1.189695
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