104,460 research outputs found
In the IP of the Beholder: Strategies for Active IPv6 Topology Discovery
Existing methods for active topology discovery within the IPv6 Internet
largely mirror those of IPv4. In light of the large and sparsely populated
address space, in conjunction with aggressive ICMPv6 rate limiting by routers,
this work develops a different approach to Internet-wide IPv6 topology mapping.
We adopt randomized probing techniques in order to distribute probing load,
minimize the effects of rate limiting, and probe at higher rates. Second, we
extensively analyze the efficiency and efficacy of various IPv6 hitlists and
target generation methods when used for topology discovery, and synthesize new
target lists based on our empirical results to provide both breadth (coverage
across networks) and depth (to find potential subnetting). Employing our
probing strategy, we discover more than 1.3M IPv6 router interface addresses
from a single vantage point. Finally, we share our prober implementation,
synthesized target lists, and discovered IPv6 topology results
Photon number statistics uncover the fluctuations in non-equilibrium lattice dynamics
Fluctuations of the atomic positions are at the core of a large class of
unusual material properties ranging from quantum para-electricity to high
temperature superconductivity. Their measurement in solids is the subject of an
intense scientific debate focused on seeking a methodology capable of
establishing a direct link between the variance of the atomic displacements and
experimentally measurable observables. Here we address this issue by means of
non-equilibrium optical experiments performed in shot-noise limited regime. The
variance of the time dependent atomic positions and momenta is directly mapped
into the quantum fluctuations of the photon number of the scattered probing
light. A fully quantum description of the non-linear interaction between
photonic and phononic fields is benchmarked by unveiling the squeezing of
thermal phonons in -quartz.Comment: 7 pages (main text), 5 figures, 11 pages (supplementary information
Sensitivity to light sterile neutrino mixing parameters with KM3NeT/ORCA
KM3NeT/ORCA is a next-generation neutrino telescope optimised for atmospheric neutrino oscillations studies. In this paper, the sensitivity of ORCA to the presence of a light sterile neutrino in a 3+1 model is presented. After three years of data taking, ORCA will be able to probe the active-sterile mixing angles θ14, θ24, θ34 and the effective angle θμe, over a broad range of mass squared difference ∆m412 ∼ [10−5, 10] eV2, allowing to test the eV-mass sterile neutrino hypothesis as the origin of short baseline anomalies, as well as probing the hypothesis of a very light sterile neutrino, not yet constrained by cosmology. ORCA will be able to explore a relevant fraction of the parameter space not yet reached by present measurements
Sensitivity to light sterile neutrino mixing parameters with KM3NeT/ORCA
KM3NeT/ORCA is a next-generation neutrino telescope optimised for atmospheric neutrino oscillations studies. In this paper, the sensitivity of ORCA to the presence of a light sterile neutrino in a 3+1 model is presented. After three years of data taking, ORCA will be able to probe the active-sterile mixing angles θ14, θ24, θ34 and the effective angle θμe, over a broad range of mass squared difference Δm241 ∼ [10−5, 10] eV2, allowing to test the eV-mass sterile neutrino hypothesis as the origin of short baseline anomalies, as well as probing the hypothesis of a very light sterile neutrino, not yet constrained by cosmology. ORCA will be able to explore a relevant fraction of the parameter space not yet reached by present measurements
Coupling of a high-energy excitation to superconducting quasiparticles in a cuprate from Coherent Charge Fluctuation Spectroscopy
Dynamical information on spin degrees of freedom of proteins or solids can be
obtained by Nuclear Magnetic Resonance (NMR) and Electron Spin Resonance (ESR).
A technique with similar versatility for charge degrees of freedom and their
ultrafast correlations could move forward the understanding of systems like
unconventional superconductors. By perturbing the superconducting state in a
high-Tc cuprate using a femtosecond laser pulse, we generate coherent
oscillations of the Cooper pair condensate which can be described by an NMR/ESR
formalism. The oscillations are detected by transient broad-band reflectivity
and found to resonate at the typical scale of Mott physics (2.6 eV), suggesting
the existence of a non-retarded contribution to the pairing interaction, as in
unconventional (non Migdal-Eliashberg) theories.Comment: Accepted for publication in the Proceedings of the National Academy
of Sciences of the U.S.A. (PNAS
Ultrafast changes in lattice symmetry probed by coherent phonons
The electronic and structural properties of a material are strongly
determined by its symmetry. Changing the symmetry via a photoinduced phase
transition offers new ways to manipulate material properties on ultrafast
timescales. However, in order to identify when and how fast these phase
transitions occur, methods that can probe the symmetry change in the time
domain are required. We show that a time-dependent change in the coherent
phonon spectrum can probe a change in symmetry of the lattice potential, thus
providing an all-optical probe of structural transitions. We examine the
photoinduced structural phase transition in VO2 and show that, above the phase
transition threshold, photoexcitation completely changes the lattice potential
on an ultrafast timescale. The loss of the equilibrium-phase phonon modes
occurs promptly, indicating a non-thermal pathway for the photoinduced phase
transition, where a strong perturbation to the lattice potential changes its
symmetry before ionic rearrangement has occurred.Comment: 14 pages 4 figure
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