3,427 research outputs found
Experimental studies of a coaxial plasma injector. 1 - Study of operational conditions
Parameter optimization, and operation of coaxial plasma injecto
Technological catch-up and strategic technology partnering in developing countries
This paper examines the trends in strategic technology partnering (STP) by firms from developing countries over the period 1980-94. The evidence shows that a small group of countries, namely the Asian NICs and Eastern Europe dominate STP activity. We also examine differences in organisational modes and how these have evolved over time, suggesting an increasing similarity between the NICs and Triad firms. Although it has been argued that these trends demonstrate the technological and economic falling behind of most developing countries, we suggest that it may also represent fundamental differences in the economic structure of these countries and the normal process of structural upgrading with development.research and development ;
Dirac fermions at the H point of graphite: Magneto-transmission studies
We report on far infrared magneto-transmission measurements on a thin
graphite sample prepared by exfoliation of highly oriented pyrolytic graphite.
In magnetic field, absorption lines exhibiting a blue-shift proportional to
sqrtB are observed. This is a fingerprint for massless Dirac holes at the H
point in bulk graphite. The Fermi velocity is found to be c*=1.02x10^6 m/s and
the pseudogap at the H point is estimated to be below 10 meV. Although the
holes behave to a first approximation as a strictly 2D gas of Dirac fermions,
the full 3D band structure has to be taken into account to explain all the
observed spectral features.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Let
Approximation of quantum control correction scheme using deep neural networks
We study the functional relationship between quantum control pulses in the
idealized case and the pulses in the presence of an unwanted drift. We show
that a class of artificial neural networks called LSTM is able to model this
functional relationship with high efficiency, and hence the correction scheme
required to counterbalance the effect of the drift. Our solution allows
studying the mapping from quantum control pulses to system dynamics and then
analysing the robustness of the latter against local variations in the control
profile.Comment: 6 pages, 3 figures, Python code available upon request. arXiv admin
note: text overlap with arXiv:1803.0516
Semiconductor quantum ring as a solid-state spin qubit
The implementation of a spin qubit in a quantum ring occupied by one or a few
electrons is proposed. Quantum bit involves the Zeeman sublevels of the highest
occupied orbital. Such a qubit can be initialized, addressed, manipulated, read
out and coherently coupled to other quantum rings. An extensive discussion of
relaxation and decoherence is presented. By analogy with quantum dots, the spin
relaxation times due to spin-orbit interaction for experimentally accessible
quantum ring architectures are calculated. The conditions are formulated under
which qubits build on quantum rings can have long relaxation times of the order
of seconds. Rapidly improving nanofabrication technology have made such ring
devices experimentally feasible and thus promising for quantum state
engineering.Comment: 16 pages, 3 figure 3 table
Interval identification of FMR parameters for spin reorientation transition in (Ga,Mn)As
In this work we report results of ferromagnetic resonance studies of a 6% 15
nm (Ga,Mn)As layer, deposited on (001)-oriented GaAs. The measurements were
performed with in-plane oriented magnetic field, in the temperature range
between 5K and 120K. We observe a temperature induced reorientation of the
effective in-plane easy axis from [-110] to [110] direction close to the Curie
temperature. The behavior of magnetization is described by anisotropy fields,
H_{eff} (= 4\piM -H_{2\perp}), H_{2\parallel}, and H_{4\parallel}. In order to
precisely investigate this reorientation, numerical values of anisotropy fields
have been determined using powerful - but still largely unknown - interval
calculations. In simulation mode this approach makes possible to find all the
resonance fields for arbitrarily oriented sample, which is generally
intractable analytically. In 'fitting' mode we effectively utilize full
experimental information, not only those measurements performed in special,
distinguished directions, to reliably estimate the values of important physical
parameters as well as their uncertainties and correlations.Comment: 3 pages, 3 figures. Presented at The European Conference "Physics of
Magnetism 2011" (PM'11), June 27 - July 1, 2011, Poznan, Polan
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