2,229 research outputs found
Argon assisted chemical vapor deposition of CrO: an efficient process leading to high quality epitaxial films
A comparative study of the structural, microstructural and magnetic
properties of CrO thin films grown onto (110) and (100) TiO rutile
single crystal substrates by chemical vapor deposition (CVD), using CrO as
chromium precursor and either oxygen or argon as carrier gas is presented. Our
results show that growth under argon carrier gas leads to high quality CrO
epilayers with structural and magnetic properties similar to those obtained
using the more standard oxygen carrier gas. Furthermore, we interpret the
larger magnetic coercivity observed for the (110) oriented films in terms of
their microstructure, in particular of the highest strain and edge roughness of
the building structures of the CrO epilayers, which are settled by the
substrate crystallographic orientation.Comment: 27 pages, 2 tables, 8 figure
On the quantumness of correlations in nuclear magnetic resonance
Nuclear Magnetic Resonance (NMR) was successfully employed to test several
protocols and ideas in Quantum Information Science. In most of these
implementations the existence of entanglement was ruled out. This fact
introduced concerns and questions about the quantum nature of such bench tests.
In this article we address some issues related to the non-classical aspects of
NMR systems. We discuss some experiments where the quantum aspects of this
system are supported by quantum correlations of separable states. Such
quantumness, beyond the entanglement-separability paradigm, is revealed via a
departure between the quantum and the classical versions of information theory.
In this scenario, the concept of quantum discord seems to play an important
role. We also present an experimental implementation of an analogous of the
single-photon Mach-Zehnder interferometer employing two nuclear spins to encode
the interferometric paths. This experiment illustrate how non-classical
correlations of separable states may be used to simulate quantum dynamics. The
results obtained are completely equivalent to the optical scenario, where
entanglement (between two field modes) may be present
Ionization rates in a Bose-Einstein condensate of metastable Helium
We have studied ionizing collisions in a BEC of He*. Measurements of the ion
production rate combined with measurements of the density and number of atoms
for the same sample allow us to estimate both the 2 and 3-body contributions to
this rate. A comparison with the decay of the number of condensed atoms in our
magnetic trap, in the presence of an rf-shield, indicates that ionizing
collisions are largely or wholly responsible for the loss. Quantum depletion
makes a substantial correction to the 3-body rate constant.Comment: 4 pages, 3 figure
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