2,687 research outputs found
Spectra of ultrabroadband squeezed pulses and the finite-time Unruh-Davies effect
We study spectral properties of quantum radiation of ultimately short
duration. In particular, we introduce a continuous multimode squeezing operator
for the description of subcycle pulses of entangled photons generated by a
coherent-field driving in a thin nonlinear crystal with second order
susceptibility. We find the ultrabroadband spectra of the emitted quantum
radiation perturbatively in the strength of the driving field. These spectra
can be related to the spectra expected in an Unruh-Davies experiment with a
finite time of acceleration. In the time domain, we describe the corresponding
behavior of the normally ordered electric field variance.Comment: 11 pages, 5 figure
Efeito da aplicação do lodo de esgoto (Biossólido) sobre a produção e decomposição do folhedo de Eucalyptus grandis e sobre o retorno de nutrientes ao solo, em Itatinga-SP.
O tratamento do esgoto urbano gera um resíduo denominado lodo de esgoto que pode ser utilizado para aumentar a produtividade de culturas agrícolas e florestais. Este artigo apresenta o efeito que a aplicação de doses crescentes de biossólido (O a 40 tlha), produzido na ETE de Barueri da SABESP - SP, provocou sobre o retorno de nutrientes ao solo, através da produção de folhedo (derrubada de folhas senescentes das árvores) e também sobre a taxa de decomposição do folhedo acumulado sobre o solo (manta orgânica) em um talhão experimental de Eucalyptus grandis, localizado na Estação Experimental de Ciências Florestais da ESALQ/USP em Itatinga - SP. Após três anos de coleta mensal do folhedo, o tratamento onde foram aplicadas 40 t ha-1 de biossólido, depositou 4.828 kg ha-1 de folhedo a mais do que o testemunha, devolvendo ao solo cerca de cinco vezes mais Ca, duas vezes mais N e três vezes mais P. Foi registrado também um aumento de 40% na taxa de decomposição do folhedo, quando comparado com o tratamento testemunha. Os vários resultados obtidos na Estação Experimental de Ciências Florestais da ESALQ/USP em Itatinga, confirmam a hipótese de que a aplicação do biossólido altera os padrões de ciclagem dos nutrientes, intensificando o retorno de nutrientes e acelerando sua incorporação ao solo
Subcycle squeezing of light from a time flow perspective
Light as a carrier of information and energy plays a fundamental role in both
general relativity and quantum physics, linking these areas that are still not
fully compliant with each other. Its quantum nature and spatio-temporal
structure are exploited in many intriguing applications ranging from novel
spectroscopy methods of complex many-body phenomena to quantum information
processing and subwavelength lithography. Recent access to subcycle quantum
features of electromagnetic radiation promises a new class of time-dependent
quantum states of light. Paralleled with the developments in attosecond
science, these advances motivate an urgent need for a theoretical framework
that treats arbitrary wave packets of quantum light intrinsically in the time
domain. Here, we formulate a consistent time domain theory of the generation
and sampling of few-cycle and subcycle pulsed squeezed states, allowing for a
relativistic interpretation in terms of induced changes in the local flow of
time. Our theory enables the use of such states as a resource for novel
ultrafast applications in quantum optics and quantum information.Comment: 24 pages, 7 figures (including supplementary information
Advances in imaging THGEM-based detectors
The thick GEM (THGEM) [1] is an "expanded" GEM, economically produced in the
PCB industry by simple drilling and etching in G-10 or other insulating
materials (fig. 1). Similar to GEM, its operation is based on electron gas
avalanche multiplication in sub-mm holes, resulting in very high gain and fast
signals. Due to its large hole size, the THGEM is particularly efficient in
transporting the electrons into and from the holes, leading to efficient
single-electron detection and effective cascaded operation. The THGEM provides
true pixilated radiation localization, ns signals, high gain and high rate
capability. For a comprehensive summary of the THGEM properties, the reader is
referred to [2, 3]. In this article we present a summary of our recent study on
THGEM-based imaging, carried out with a 10x10 cm^2 double-THGEM detector.Comment: 3 pages, 3 figures. Presented at the 10th Pisa Meeting on Advanced
Detectors; ELBA-Italy; May 21-27 200
A Capacidade de rebrota das castanheiras.
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