315,778 research outputs found
The Microscopic Response Method: theory of transport for systems with both topological and thermal disorder
In this paper, we review and substantially develop the recently proposed
"Microscopic Response Method", which has been devised to compute transport
coefficients and especially associated temperature dependence in complex
materials. The conductivity and Hall mobility of amorphous semiconductors and
semiconducting polymers are systematically derived, and shown to be more
practical than the Kubo formalism. The effect of a quantized lattice (phonons)
on transport coefficients is fully included and then integrated out, providing
the primary temperature dependence for the transport coefficients. For
higher-order processes, using a diagrammatic expansion, one can consistently
include all important contributions to a given order and directly write out the
expressions of transport coefficients for various processes.Comment: paper: 12.3 pages, 13 figures, submitted to physica status solidi
(b), supporting information: 14.5 page
Partial radiogenic heat model for Earth revealed by geoneutrino measurements
The Earth has cooled since its formation, yet the decay of radiogenic isotopes, and in particular uranium, thorium and
potassium, in the planet’s interior provides a continuing heat source. The current total heat flux from the Earth to space is 44:2±1.0 TW, but the relative contributions from residual primordial heat and radiogenic decay remain uncertain. However, radiogenic decay can be estimated from the flux of geoneutrinos, electrically neutral particles that are emitted during radioactive decay and can pass through the Earth virtually unaffected. Here we combine precise measurements of the geoneutrino flux from the Kamioka Liquid-Scintillator Antineutrino Detector, Japan, with existing measurements from the Borexino detector, Italy.We find that decay of uranium-238 and thorium-232 together contribute 20.0^(+8.8)_(-8.6)TW to Earth’s heat
flux. The neutrinos emitted from the decay of potassium-40 are below the limits of detection in our experiments, but are known to contribute 4TW. Taken together, our observations indicate that heat from radioactive decay contributes about half of Earth’s total heat flux. We therefore conclude that Earth’s primordial heat supply has not yet been exhausted
Constraints on θ_(13) from a three-flavor oscillation analysis of reactor antineutrinos at KamLAND
We present new constraints on the neutrino oscillation parameters Δm^2_(21), θ_(12), and θ_(13) from a three flavor
analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 x 10^(32) target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis (θ_(13) = 0) of the KamLAND and solar data yields the best-fit values tan^2θ_(12) = 0.444^(+0.036)_(-0.030) and Δm^2_(21) = 7.50^(+0.19)_(-0.20) x 10^(-5) eV^2; a three-flavor analysis with θ13 as a free parameter yields the best-fit values tan^2θ_(12) = 0.452^(+0.035)_(-0.033), Δm^2_(21) = 7.50^(+0.19)_(-0.20) x 10^(-5) eV^2, and sin^2θ_(13) = 0.020^(+0.016)_(-0.016). This θ_(13) interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global θ_(13) analysis, incorporating the CHOOZ, atmospheric, and accelerator data, which indicates sin^2θ_(13) = 0.009^(+0.013)-_(0.007). A nonzero value is suggested, but only at the 79% C.L
Quantum Computing via The Bethe Ansatz
We recognize quantum circuit model of computation as factorisable scattering
model and propose that a quantum computer is associated with a quantum
many-body system solved by the Bethe ansatz. As an typical example to support
our perspectives on quantum computation, we study quantum computing in
one-dimensional nonrelativistic system with delta-function interaction, where
the two-body scattering matrix satisfies the factorisation equation (the
quantum Yang--Baxter equation) and acts as a parametric two-body quantum gate.
We conclude by comparing quantum computing via the factorisable scattering with
topological quantum computing.Comment: 6 pages. Comments welcom
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