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

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 $4d$ transition metals. The self-electromigration results for aluminum and the noble metals compare well with experimental data. For the $4d$ 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