9,660 research outputs found
Slow optical solitons via intersubband transitions in a semiconductor quantum well
We show the formation of bright and dark slow optical solitons based on
intersubband transitions in a semiconductor quantum well (SQW). Using the
coupled Schrodinger-Maxwell approach, we provide both analytical and numerical
results. Such a nonlinear optical process may be used for the control
technology of optical delay lines and optical buffers in the SQW solid-state
system. With appropriate parameters, we also show the generation of a large
cross-phase modulation (XPM). Since the the intersubband energy level can be
easily tuned by an external bias voltage, the present investigation may open
the possibility for electrically controlled phase modulator in the solid-state
system
Constraining f(R) gravity in solar system, cosmology and binary pulsar systems
The gravity can be cast into the form of a scalar-tensor theory, and
scalar degree of freedom can be suppressed in high-density regions by the
chameleon mechanism. In this article, for the general gravity, using a
scalar-tensor representation with the chameleon mechanism, we calculate the
parameterized post-Newtonian parameters and , the effective
gravitational constant , and the effective cosmological constant
. In addition, for the general gravity, we also
calculate the rate of orbital period decay of the binary system due to
gravitational radiation. Then we apply these results to specific models
(Hu-Sawicki model, Tsujikawa model and Starobinsky model) and derive the
constraints on the model parameters by combining the observations in solar
system, cosmological scales and the binary systems.Comment: LaTex, 19 pages,1 figure, typo corrected. To appear in Physics
Letters
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