536 research outputs found
Non-separated states from squeezed dark-state polaritons in electromagnetically-induced-transparency media
Within the frame of quantized dark-state polaritons in
electromagnetically-induced-transparency media, noise fluctuations in the
quadrature components are studied. Squeezed state transfer, quantum
correlation, and noise entanglement between probe field and atomic polarization
are demonstrated in single- and double- configurations, respectively.
Even though a larger degree of squeezing parameter in the continuous variable
helps to establish stronger quantum correlations, inseparability criterion is
satisfied only within a finite range of squeezing parameter. The results
obtained in the present study may be useful for guiding experimental
realization of quantum memory devices for possible applications in quantum
information and computation.Comment: 12 pages, 7 figure
Gain-assisted quantum heat engine based on electromagnetically induced transparency
We present a scheme to realize a gain-assisted quantum heat engine (QHE)
based on electromagnetically induced transparency (EIT). We consider a
three-level { \Lambda}-type atomic system that interacts with two thermal
reservoirs and a coupling field. The gain without inversion is induced in the
system via spontaneously generated coherence (SGC) between two lower levels. To
generate SGC, some rigorous conditions must be maintained, but its effect on
the system's dynamics are significant, resulting in an enhancement of the
emission cross-section and spectral brightness of the QHE
Lasing on nonlinear localized waves in curved geometry
The use of geometrical constraints opens many new perspectives in photonics
and in fundamental studies of nonlinear waves. By implementing surface
structures in vertical cavity surface emitting lasers as manifolds for curved
space, we experimentally study the impacts of geometrical constraints on
nonlinear wave localization. We observe localized waves pinned to the maximal
curvature in an elliptical-ring, and confirm the reduction in the localization
length of waves by measuring near and far field patterns, as well as the
corresponding dispersion relation. Theoretically, analyses based on a
dissipative model with a parabola curve give good agreement remarkably to
experimental measurement on the transition from delocalized to localized waves.
The introduction of curved geometry allows to control and design lasing modes
in the nonlinear regime.Comment: 6 pages, 6 figure
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