2,912 research outputs found
An Appraisal of FOPIM Fast-converging Perturbation Method
Appraisal of first order perturbation iteration fast converging metho
Noiseless signal amplification using positive electro-optic feedforward
We propose an electro-optic feedforward scheme which can in principle produce perfect noiseless signal amplification (signal transfer coefficient of T s = 1). We demonstrate the scheme experimentally and report, for a signal gain of 13.4 dB, a signal transfer coefficient of T s = 0.88 which is limited mainly by detector efficiencies (92%). The result clearly exceeds the standard quantum limit, T s = 0.5, set by the high gain limit of a phase insensitive linear amplifier. We use the scheme to amplify a small signal carried by 35% amplitude squeezed light and demonstrate that, unlike the fragile squeezed input, the signal amplified output is robust to propagation losses
Unconditional Continuous Variable Dense Coding
We investigate the conditions under which unconditional dense coding can be
achieved using continuous variable entanglement. We consider the effect of
entanglement impurity and detector efficiency and discuss experimental
verification. We conclude that the requirements for a strong demonstration are
not as stringent as previously thought and are within the reach of present
technology
Generation of a frequency comb of squeezing in an optical parametric oscillator
The multimode operation of an optical parametric oscillator (OPO) operating below threshold is calculated. We predict that squeezing can be generated in a comb that is limited only by the phase matching bandwidth of the OPO. Effects of technical noise on the squeezing spectrum are investigated. It is shown that maximal squeezing can be obtained at high frequency even in the presence of seed laser noise and cavity length fluctuations. Furthermore the spectrum obtained by detuning the laser frequency off OPO cavity resonance is calculated
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A decision analytical framework for evaluating technical innovation and diffusion: The case of electronic ballasts for commercial buildings
The authors present a decision analytical framework for studying the decision to purchase new energy-efficient magnetic ballasts for commercial buildings as a special case study for understanding the decision environment that could either encourage or retard the penetration of new carbon-saving technologies. The framework is particularly germane to situations where uncertainty in the investment outcome prevails as a dominant dimension of the problem. It allows the policy analyst to consider policies that operate through other considerations than through the price alone. A key effect is how a policy will either truncate a probability distribution to remove the worst outcomes or cause the probability distribution to narrow. Such considerations appear important when studying information programs, vendor warranty, and other factors that condition the investment decision
Theory for the electromigration wind force in dilute alloys
A multiple scattering formulation for the electromigration wind force on
atoms in dilute alloys is developed. The theory describes electromigration via
a vacancy mechanism. The method is used to calculate the wind valence for
electromigration in various host metals having a close-packed lattice
structure, namely aluminum, the noble metals copper, silver and gold and the
transition metals. The self-electromigration results for aluminum and the
noble metals compare well with experimental data. For the metals small
wind valences are found, which make these metals attractive candidates for the
experimental study of the direct valence.Comment: 18 pages LaTeX, epsfig, 8 figures. to appear in Phys. Rev. B 56 of
15/11/199
Community detection in networks with positive and negative links
Detecting communities in complex networks accurately is a prime challenge,
preceding further analyses of network characteristics and dynamics. Until now,
community detection took into account only positively valued links, while many
actual networks also feature negative links. We extend an existing Potts model
to incorporate negative links as well, resulting in a method similar to the
clustering of signed graphs, as dealt with in social balance theory, but more
general. To illustrate our method, we applied it to a network of international
alliances and disputes. Using data from 1993--2001, it turns out that the world
can be divided into six power blocs similar to Huntington's civilizations, with
some notable exceptions.Comment: 7 pages, 2 figures. Revised versio
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