459 research outputs found
Additional Exploratory Photoelastic Studies in Stress Wave Propagation
In a previous report to the sponsor, the design and
description of a high speed framing camera was presented along with several film strips representing the results of a series of qualitative investigations of dynamic stress wave phenomena. These studies included crack propagation, layered media, compressed bars and beams, and cross sections of rocket heads.
As part of a continuing study in these and related fields,
a final report is submitted covering (1) exploratory experimental studies of shock wave propagation initiated by explosive caps and by nitrogen shock wave impingement, and (2) theoretical studies of a series of dynamic stress wave problems carried out in conjunction with the overall problem
Elastic properties of B-C-N films grown by N2-reactive sputtering from boron carbide targets
The following article appeared in Journal of Applied Physics 114.21 (2013): 213508 and may be found at http://scitation.aip.org/content/aip/journal/jap/114/21/10.1063/1.4837655Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B4C target and N2 as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions.This work has been supported by Spanish MINECO under contracts MAT2009-08786 and MAT2012-37276- C03-01 as well as by the Madrid Regional Government though contract S2009/MAT-1756
Dynamical decoupling of unbounded Hamiltonians
We investigate the possibility to suppress interactions between a finite
dimensional system and an infinite dimensional environment through a fast
sequence of unitary kicks on the finite dimensional system. This method, called
dynamical decoupling, is known to work for bounded interactions, but physical
environments such as bosonic heat baths are usually modelled with unbounded
interactions, whence here we initiate a systematic study of dynamical
decoupling for unbounded operators. We develop a sufficient decoupling
criterion for arbitrary Hamiltonians and a necessary decoupling criterion for
semibounded Hamiltonians. We give examples for unbounded Hamiltonians where
decoupling works and the limiting evolution as well as the convergence speed
can be explicitly computed. We show that decoupling does not always work for
unbounded interactions and provide both physically and mathematically motivated
examples.Comment: 18 pages, 3 figure
Frozen and Invariant Quantum Discord under Local Dephasing Noise
In this chapter, we intend to explore and review some remarkable dynamical
properties of quantum discord under various different open quantum system
models. Specifically, our discussion will include several concepts connected to
the phenomena of time invariant and frozen quantum discord. Furthermore, we
will elaborate on the relation of these two phenomena to the non-Markovian
features of the open system dynamics and to the usage of dynamical decoupling
protocols.Comment: 29 pages, 8 figure
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