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

A Frequency-Domain Criterion for Global Stability of Systems with Angular Coordinates

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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