4,300 research outputs found
True photo-counting statistics of multiple on-off detectors
We derive a closed photo-counting formula, including noise counts and a
finite quantum efficiency, for photon number resolving detectors based on
on-off detectors. It applies to detection schemes such as array detectors and
multiplexing setups. The result renders it possible to compare the
corresponding measured counting statistics with the true photon number
statistics of arbitrary quantum states. The photo-counting formula is applied
to the discrimination of photon numbers of Fock states, squeezed states, and
odd coherent states. It is illustrated for coherent states that our formula is
indispensable for the correct interpretation of quantum effects observed with
such devices.Comment: 7 pages, 4 figure
Sustainable use of low flow reaches downstream energy generation dams
The paper describes the issues of water quality in low flow reaches downstream energy generation dams. These reaches
should maintain a minimum water flow in order to guarantee adequate ecological conditions in the water body. A case
study is presented with respect to the longest low flow reach in Brazil, focusing mainly on environmental and regulatory
aspects. Water quality in this reach should be enhanced by the construction of some intermediate dikes, which will allow
the sedimentation of particulate matter and the formation of small reservoirs for the growth of aquatic species. A concern
remains only with phosphorus concentrations, since the environment will change from a lotic to a lentic condition
Balanced homodyne detection with on-off detector systems: Observable nonclassicality criteria
Driven by single photon detection requirements especially for quantum
information sciences, the theory of arrays of off-on detectors has been well
developed and applied. However for a comprehensive characterization of
nonclassicality one also needs phase sensitive properties. This missing link is
fulfilled by the theory of phase sensitive click counting measurements. This
theory is presented. It unifies the balanced homodyne detection for high
intensities with the click detection in the few photon regime. We formulate and
apply a hierarchy of nonlinear squeezing conditions to probe quantum effects
beyond standard squeezing. Imperfections stemming from fluctuations of the
local oscillator, detector efficiency, and dark count rates are considered.
Experimentally accessible sampling formulas are given which can be applied
without time consuming data processing. Our phase-sensitive click detection
theory paves the way towards novel applications of nonclassical light in
quantum metrology.Comment: close to published EPL versio
Quantum Correlations from the Conditional Statistics of Incomplete Data
We study, in theory and experiment, the quantum properties of correlated
light fields measured with click-counting detectors providing incomplete
information on the photon statistics. We establish a correlation parameter for
the conditional statistics, and we derive the corresponding nonclassicality
criteria for detecting conditional quantum correlations. Classical bounds for
Pearson's correlation parameter are formulated that allow us, once they are
violated, to determine nonclassical correlations via the joint statistics. On
the one hand, we demonstrate nonclassical correlations in terms of the joint
click statistics of light produced by a parametric down conversion source. On
the other hand, we verify quantum correlations of a heralded, split
single-photon state via the conditional click statistics together with a
generalization to higher-order moments. We discuss the performance of the
presented nonclassicality criteria to successfully discern joint and
conditional quantum correlations. Remarkably, our results are obtained without
making any assumptions on the response function, quantum efficiency, and
dark-count rate of the photodetectors
Multiscale Modeling of Binary Polymer Mixtures: Scale Bridging in the Athermal and Thermal Regime
Obtaining a rigorous and reliable method for linking computer simulations of
polymer blends and composites at different length scales of interest is a
highly desirable goal in soft matter physics. In this paper a multiscale
modeling procedure is presented for the efficient calculation of the static
structural properties of binary homopolymer blends. The procedure combines
computer simulations of polymer chains on two different length scales, using a
united atom representation for the finer structure and a highly coarse-grained
approach on the meso-scale, where chains are represented as soft colloidal
particles interacting through an effective potential. A method for combining
the structural information by inverse mapping is discussed, allowing for the
efficient calculation of partial correlation functions, which are compared with
results from full united atom simulations. The structure of several polymer
mixtures is obtained in an efficient manner for several mixtures in the
homogeneous region of the phase diagram. The method is then extended to
incorporate thermal fluctuations through an effective chi parameter. Since the
approach is analytical, it is fully transferable to numerous systems.Comment: in press, 13 pages, 7 figures, 6 table
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