20,212 research outputs found

    Linking Ultracold Polar Molecules

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    We predict that pairs of polar molecules can be weakly bound together in an ultracold environment, provided that a dc electric field is present. The field that links the molecules together also strongly influences the basic properties of the resulting dimer, such as its binding energy and predissociation lifetime. Because of their long-range character these dimers will be useful in disentangling cold collision dynamics of polar molecules. As an example, we estimate the microwave photoassociation yield for OH-OH cold collisions.Comment: 4 pages 2 figure

    Interference fringes with maximal contrast at finite coherence time

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    Interference fringes can result from the measurement of four-time fourth-order correlation functions of a wave field. These fringes have a statistical origin and, as a consequence, they show the greatest contrast when the coherence time of the field is finite. A simple acoustic experiment is presented in which these fringes are observed, and it is demonstrated that the contrast is maximal for partial coherence. Random telegraph phase noise is used to vary the field coherence in order to highlight the problem of interpreting this interference; for this noise, the Gaussian moment theorem may not be invoked to reduce the description of the interference to one in terms of first-order interference.M.W. Hamilto

    Metamaterials for light rays: ray optics without wave-optical analog in the ray-optics limit

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    Volumes of sub-wavelength electromagnetic elements can act like homogeneous materials: metamaterials. In analogy, sheets of optical elements such as prisms can act ray-optically like homogeneous sheet materials. In this sense, such sheets can be considered to be metamaterials for light rays (METATOYs). METATOYs realize new and unusual transformations of the directions of transmitted light rays. We study here, in the ray-optics and scalar-wave limits, the wave-optical analog of such transformations, and we show that such an analog does not always exist. Perhaps, this is the reason why many of the ray-optical possibilities offered by METATOYs have never before been considered.Comment: 10 pages, 3 figures, references update

    Experimental verification of minima in excited long-range Rydberg states of Rb_2

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    Recent theoretical studies with alkali atoms A^{\ast} excited to high Rydberg states predicted the existence of ultra long-range molecular bound states. Such excited dimers have large electric dipole moments which, in combination with their long radiative lifetimes, make them excellent candidates for manipulation in applications. This letter reports on experimental investigations of the self-broadening of Rb principal series lines, which revealed multiple satellites in the line wings. The positions of the satellites agree quantitatively with theoretically-predicted minima in the excited long-range Rydberg states of Rb2_2.Comment: 3 figures, 5 pages in two-column forma

    Hard to recall but easy to judge: retrieval strategies in social information processing

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    The present research distinguishes two different retrieval modes: exhaustive and heuristic retrieval. Whereas exhaustive retrieval is elemental and retrieves specific memory traces, the output of heuristic retrieval is a memory composite. Different memory tasks depend upon these two retrieval modes in various degrees. Using a part-list cueing paradigm, we found a dissociation: providing part-list cues hindered the retrieval of the non-cued behaviors in free recall but boosted frequency estimates. In a second study, using a collaborative recall paradigm, each of three participants recalled one of the previously presented behaviors in turn. We hypothesized that behaviors recalled by other participants would become hyper-accessible, inhibiting the retrieval of non-recalled behaviors but boosting the corresponding frequency estimates relative to non-collaborative recall conditions. The results supported the hypotheses. The parallelism of the results of the two studies suggests that retrieval interference or inhibition is a crucial feature of social memory.info:eu-repo/semantics/acceptedVersio

    Enhancing the comparability between part-list cueing and collaborative recall

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    The effects of part-list cueing and of collaborative recall in memory performance have been recently addressed as parallel phenomena. Notably they both impair recall (and boost frequency estimates) and they have been explained by the same underlying mechanisms. However the comparability between the two paradigms is hindered by a number of procedural differences. The main contribution of this paper is the introduction of a new paradigm that makes standard part-list cueing and collaborative recall more comparable. In our study we compared free recall and frequency estimates of participants in a non-cueing condition with the same performance in a standard partlist cueing condition and in a condition in which part-list cues were gradually presented during recall (as it occurs in collaborative recall). Results indicate that the effects of part-list cueing continued to be reliable in both cueing conditions. Namely, recall was impaired and frequency estimates were boosted relatively to a non-cueing condition. The results obtained with this new method that enhances the direct comparability of the two paradigms, provides further evidence for the parallel between the two effects.info:eu-repo/semantics/acceptedVersio

    Quaternion Analysis for Generalized Electromagnetic Fields of Dyons in Isotropic Medium

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    Quaternion analysis of time dependent Maxwell's equations in presence of electric and magnetic charges has been developed and the solutions for the classical problem of moving charges (electric and magnetic) are obtained in unique, simple and consistent manner

    On the spectra of the quantized action-variables of the compactified Ruijsenaars-Schneider system

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    A simple derivation of the spectra of the action-variables of the quantized compactified Ruijsenaars-Schneider system is presented. The spectra are obtained by combining Kahler quantization with the identification of the classical action-variables as a standard toric moment map on the complex projective space. The result is consistent with the Schrodinger quantization of the system worked out previously by van Diejen and Vinet.Comment: Based on talk at the workshop CQIS-2011 (Protvino, Russia, January 2011), 12 page

    Compression and diffusion: a joint approach to detect complexity

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    The adoption of the Kolmogorov-Sinai (KS) entropy is becoming a popular research tool among physicists, especially when applied to a dynamical system fitting the conditions of validity of the Pesin theorem. The study of time series that are a manifestation of system dynamics whose rules are either unknown or too complex for a mathematical treatment, is still a challenge since the KS entropy is not computable, in general, in that case. Here we present a plan of action based on the joint action of two procedures, both related to the KS entropy, but compatible with computer implementation through fast and efficient programs. The former procedure, called Compression Algorithm Sensitive To Regularity (CASToRe), establishes the amount of order by the numerical evaluation of algorithmic compressibility. The latter, called Complex Analysis of Sequences via Scaling AND Randomness Assessment (CASSANDRA), establishes the complexity degree through the numerical evaluation of the strength of an anomalous effect. This is the departure, of the diffusion process generated by the observed fluctuations, from ordinary Brownian motion. The CASSANDRA algorithm shares with CASToRe a connection with the Kolmogorov complexity. This makes both algorithms especially suitable to study the transition from dynamics to thermodynamics, and the case of non-stationary time series as well. The benefit of the joint action of these two methods is proven by the analysis of artificial sequences with the same main properties as the real time series to which the joint use of these two methods will be applied in future research work.Comment: 27 pages, 9 figure
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