121,978 research outputs found
Quantum Illumination with Multiplexed Photodetection
No full textThe advantages of using quantum states of light for object detection are often highlighted in schemes that use simultaneous and optimal measurements. Here, we describe a theoretical but experimentally realizable quantum illumination scheme based on nonsimultaneous and nonoptimal measurements, which can maintain this advantage. In particular, we examine the multiclick-heralded two-mode-squeezed vacuum state as a probe signal in a quantum illumination process. The increase in conditioned signal intensity associated with multiclick heralding is greater than that from a single detector-heralded signal. Our results show, for lossy external conditions, the presence of the target object can be revealed earlier using multiclick measurements. We demonstrate this through sequential shot measurements based on Monte Carlo simulation
Poissonian twin-beam states and the effect of symmetrical photon subtraction in loss estimations
No full textWe have devised an experimentally realizable model generating twin-beam states whose individual beam photon statistics are varied from thermal to Poissonian (by temporal mode averaging) keeping the nonclassical mode correlation intact. We have studied the usefulness of these states for loss measurement by considering three different estimators, comparing with the correlated thermal twin-beam states generated from spontaneous parametric down conversion or four-wave mixing. We then incorporated the photon subtraction operation into the model and demonstrated their performance in loss estimations with respect to unsubtracted states at both fixed squeezing and per photon exposure of the absorbing sample. For instance, at fixed squeezing, for two photon subtraction, up to three times advantage is found. An unexpected result in the latter case is that in some operating regimes the photon subtraction scheme can also give up to 20% advantage over the correlated thermal beam result and no advantages are obtained when the statistics of each beam turns to Poissonian. We have also made a comparative study of these estimators for finding the best measurement for loss estimations. We present results for all the values of the model parameters changing the statistics of twin-beam states from thermal t
Single-phase and correlated-phase estimation with multiphoton annihilated squeezed vacuum states: An energy-balancing scenario
No full textIn recent years, several works have demonstrated the advantage of photon-subtracted Gaussian states for various quantum optics and information protocols. In most of these works, the relation between the advantages and the usual increasing energy of the quantum state related to photon subtraction was not clearly investigated. In this paper, we study the performance of an interferometer injected with multiphoton-annihilated squeezed vacuum states mixed with coherent states for both single- and correlated-phase estimations. For single-phase estimation, although the use of multiphoton-annihilated squeezed vacuum states at low mean photons per mode provides an advantage compared to classical strategy, when the total input energy is held fixed, the advantage due to photon subtraction is completely lost. However, for the correlated case in the analogous scenario, some advantage appears to come from both the energy rise and improvement in photon statistics. In particular quantum enhanced sensitivity with photon-subtracted states appears more robust to losses, showing an advantage of about 30% with respect to the squeezed vacuum state in the case of a realistic value of the detection efficiency
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Improving resolution-sensitivity trade off in sub-shot noise quantum imaging
No full textOne of the challenges of quantum technologies is realizing the quantum advantage, predicted for ideal systems, in real applications, which have to cope with decoherence and inefficiencies. In quantum metrology, sub-shot-noise quantum imaging (SSNQI) and sensing methods can provide genuine quantum enhancement in realistic situations. However, wide-field SSNQI schemes realized so far suffer a trade-off between the resolution and the sensitivity gain over a classical counterpart: small pixels or integrating area are necessary to achieve high imaging resolution, but larger pixels allow a better detection efficiency of quantum correlations, which means a larger quantum advantage. Here, we show how the SSNQI protocol can be optimized to significantly improve the resolution without giving up the quantum advantage in sensitivity. We show a linear resolution improvement (up to a factor 3) with respect to the simple protocol used in previous demonstrations
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
One- and two-mode squeezed light in correlated interferometry
No full textWe study in detail a system of two interferometers aimed at detecting extremely faint phase fluctuations.
This system can represent a breakthrough for detecting a faint correlated signal that would remain otherwise
undetectable even using the most sensitive individual interferometric devices, as in the case of so-called
holographic noise. The signature of this kind of noise emerges as a correlation between the output signals
of the interferometers. On the other hand, when holographic noise is absent one expects uncorrelated signals
since the time-averaged fluctuations due to shot noise and other independent contributions vanish (though limiting
the overall sensitivity).We showhowinjecting quantum light in the free ports of the interferometers can reduce the
photon noise of the system beyond the shot noise, enhancing the resolution in the phase-correlation estimation.We
analyze the use of both the two-mode squeezed vacuum and two independent squeezed states. Our results confirm
the benefit of using squeezed beams together with strong coherent beams in interferometry. We also investigate
the possible use of the two-mode squeezed vacuum, discovering interesting and unexplored areas of application
of bipartite entanglement, in particular the possibility of reaching in principle a surprising uncertainty reduction
Comparison of two ventilation modes in post-cardiac surgical patients
No full textBackground: The cardiopulmonary bypass (CPB)-associated atelectasis accounted for most of the marked post-CPB increase in shunt and hypoxemia. We hypothesized that pressure-regulated volume-control (PRVC) modes having a distinct theoretical advantage over pressure-controlled ventilation (PCV) by providing the target tidal volume at the minimum available pressure may prove advantageous while ventilating these atelactic lungs. Methods: In this prospective study, 36 post-cardiac surgical patients with a PaO 2 /FiO 2 (arterial oxygen tension/Fractional inspired oxygen) < 300 after arrival to intensive care unit (ICU), (n = 34) were randomized to receive either PRVC or PCV. Air way pressure (Paw ) and arterial blood gases (ABG) were measured at four time points [T1: After induction of anesthesia, T2: after CPB (in the ICU), T3: 1 h after intervention mode, T4: 1 h after T3]. Oxygenation index (OI) = [PaO 2 / {FiO 2 × mean airway pressure (Pmean )}] was calculated for each set of data and used as an indirect estimation for intrapulmonary shunt. Results: There is a steady and significant improvement in OI in both the groups at first hour [PCV, 27.5(3.6) to 43.0(7.5); PRVC, 26.7(2.8) to 47.6(8.2) (P = 0.001)] and second hour [PCV, 53.8(6.4); PRVC, 65.8(7.4) (P = 0.001)] of ventilation. However, the improvement in OI was more marked in PRVC at second hour of ventilation owing to significant low mean air way pressure compared to the PCV group [PCV, 8.6(0.8); PRVC, 7.7(0.5), P = 0.001]. Conclusions: PRVC may be useful in a certain group of patients to reduce intrapulmonary shunt and improve oxygenation after cardiopulmonary bypass-induced perfusion mismatch
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