Coherent Synthesis Research Articles

The Hydrothermal System of Solfatara Crater (Campi Flegrei, Italy) Inferred From Machine Learning Algorithms

Two machine learning algorithms were applied to three multivariate datasets acquired at Solfatara volcano. Our aim was to find an unbiased and coherent synthesis among the large amount of data acquired within the crater and along two orthogonal vertical NNE- and WNW-trending cross-sections. The first algorithm includes a new approach for a soft K-means clustering based on the use of the silhouette index to control the color palette of the clusters. The second algorithm which uses the self-organizing maps incorporates an alternative method for choosing the number of nodes of the neural network which aims to avoid the need for downstream clustering of the results of the classification. Both methods achieved an objective characterization of the shallow hydrothermal system of the volcano, enhancing and highlighting subtle geophysical anomalies likely correlated to structural pathways of deep magmatic degassing. Comparison between the results of K-means and self-organizing maps on the datasets with the largest number of nodes confirms that, with respect to the K-means, self-organizing maps compress the data in a way that better highlights finer details of the original data. However, the choice of the coloring scheme of the neurons is critical for an effective visualization of the results. Unsupervised integration of the three multivariate datasets allowed us to spatially correlate, with a high-degree of confidence, the geophysical anomalies recorded at the surface of the crater with those recorded at the subsurface along the two cross-sections. it also allowed us to associate those anomalies to different hydrothermal features such as shallow gas-saturated and water-saturated zones and their underlying fractures/faults feeding system. Our results suggest that the main shallow structural patterns, which influence the hydrothermal dynamics at Solfatara volcano, remained substantially unchanged in the last fifteen years. Our approach shows that the use of clustering methods to interpret multivariate data reduces interpretation uncertainties and achieves an improved understanding of the complex dynamics occurring in volcanoes.

Controllable Kerr and Raman-Kerr frequency combs in functionalized microsphere resonators

Abstract Optical frequency comb (OFC) based on the whispering-gallery-mode microresonator has various potential applications in fundamental and applied areas. Once the solid microresonator is fabricated, its structure parameters are generally unchanged. Therefore, realizing the tunability of the microresonator OFC is an important precondition for many applications. In this work, we proposed and demonstrated the tunable Kerr and Raman-Kerr frequency combs using the ultrahigh-quality-factor (Q) functionalized silica microsphere resonators, which are coated with iron oxide nanoparticles on their end surfaces. The functionalized microsphere resonator possesses Q factors over 108 and large all-optical tunability due to the excellent photothermal performance of the iron oxide nanoparticles. We realized a Kerr frequency comb with an ultralow threshold of 0.42 mW and a comb line tuning range of 0.8 nm by feeding the control light into the hybrid microsphere resonator through its fiber stem. Furthermore, in order to broaden the comb span, we realized a Raman-Kerr frequency comb with a span of about 164 nm. Meanwhile, we also obtained a comb line tuning range of 2.67 nm for the Raman-Kerr frequency comb. This work could find potential applications in wavelength-division multiplexed coherent communications and optical frequency synthesis.

Multiple Jobholding: An Integrative Systematic Review and Future Research Agenda

Despite sizable but varying estimates of multiple jobholding (MJH) and decades of research across disciplines (e.g., management, economics, sociology, health and medicine), our understanding of MJH is rather limited. The purpose of this review is to provide a coherent synthesis of the literature on MJH, or working more than one job. Beginning with a discussion of the motivations and demographic predictors that forecast MJH, we note a distinct divide between the research that predicts MJH and the research that examines outcomes, with few studies exploring how motivations might relate to MJH experiences and outcomes. Another significant observation in this review is the inconsistency of findings across and within disciplines regarding whether MJH is depleting or enriching. Using this framework to organize our review, we attempt to reconcile the generally mixed results by presenting research on mechanisms and boundary conditions of MJH to explain how and when multiple jobholders (MJHers) are depleted or enriched. By integrating findings from the literature, we are able to articulate more clearly the paths of depletion and enrichment and discuss how push versus pull-based motivations to hold multiple jobs likely predict these pathways. Finally, we provide a strategic agenda highlighting areas where additional research is urgently needed to equip scholars with practical knowledge on how to help MJHers manage their multiple work roles and how to help organizations manage MJHers.

Coherent beam combining based on the SPGD algorithm with a momentum term

The stochastic parallel gradient descent with a momentum term (named MomSPGD) algorithm is innovatively presented and applied for coherent beam combining to substitute for the traditional SPGD algorithm. The feasibility of coherent synthesis system using the MomSPGD algorithm is validated through numerical simulations and experiments. The results of the simulations and the experiment indicate that the proposed algorithm can improve convergence speed and immunity of the synthesis system compared with the traditional SPGD algorithm.

Understanding quantum mechanics: a review and synthesis in precise language

AbstractThis review, of the understanding of quantum mechanics, is broad in scope, and aims to reflect enough of the literature to be representative of the current state of the subject. To enhance clarity, the main findings are presented in the form of a coherent synthesis of the reviewed sources. The review highlights core characteristics of quantum mechanics. One is statistical balance in the collective response of an ensemble of identically prepared systems, to differing measurement types. Another is that states are mathematical terms prescribing probability aspects of future events, relating to an ensemble of systems, in various situations. These characteristics then yield helpful insights on entanglement, measurement, and widely-discussed experiments and analyses. The review concludes by considering how these insights are supported, illustrated and developed by some specific approaches to understanding quantum mechanics. The review uses non-mathematical language precisely (terms defined) and rigorously (consistent meanings), and uses only such language. A theory more descriptive of independent reality than is quantum mechanics may yet be possible. One step in the pursuit of such a theory is to reach greater consensus on how to understand quantum mechanics. This review aims to contribute to achieving that greater consensus, and so to that pursuit.

Corrigendum to “Coherent synthesis of genomic associations with phenotypes and home environments”

We discovered an error in our analyses (Lasky, Forester, & Reimherr, 2018). The specific error was in the analysis of enrichment of (a) SNPs associated with G×E for fitness with (b) SNPs associated with G×E for flowering time under experimental warming (Li, Cheng, Spokas, Palmer, & Borevitz, 2014). The error resulted from a failure to convert SNPs from two different versions of the Arabidopsis reference genome assembly: from TAIR8 (used in Li et al., 2014 supplemental materials, which we reanalyzed in our paper) to TAIR9 (used in our analyses of G×E for fitness, Lasky et al., 2018). We fixed the error, converting the Li et al. (2014) SNPs from TAIR8 to TAIR9 and reanalyzing the enrichments. This reanalysis showed (as in Lasky et al., 2018) that SNPs associated with flowering time response to experimental warming (G×E, Li et al., 2014) were significantly and most strongly enriched in SNPs associated with change in fitness across gradients of growing season minimum temperatures (Table 1 here, which supersedes the relevant row from Table 2 in Lasky et al., 2018). Additionally, reanalysis showed a weaker, but significant enrichment of flowering time G×E SNPs in SNPs associated with change in fitness across gradients of growing season variability in precipitation. As in Lasky et al. (2018), SNPs associated with change in fitness across gradients of annual aridity or winter cold were not enriched in flowering time G×E SNPs. In summary, our conclusion that “variants causing flowering time plasticity drive changes in fitness across growing season temperature gradients” (Lasky et al., 2018) is supported by this reanalysis and corrigendum. Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Simple method for simultaneous long-term stabilization of relative timing and carrier-envelope phase in waveform synthesis

We present an f-to-2f interferometry method to simultaneously measure and control the relative timing (RT) and carrier-envelope phase (CEP) of an arbitrarily tailored optical-field waveform. Long-term stabilization of the phase-locking system results in a CEP stability of 280 mrad and a RT stability of 110 attosecond over 8 h at a repetition rate of 1 kHz. The synthesized optical field characterized by a transient-grating frequency-resolved optical gating delivers 3.8-fs near single-cycle waveforms. This technique constitutes a versatile tool for coherent pulse synthesis, which can be applied in experiments using a dual-color light field for high-harmonic generation and attosecond timing precision pump-probe spectroscopy.

What evidence exists on the effectiveness of the techniques and management approaches used to improve the productivity of field grown tomatoes under conditions of water-, nitrogen- and/or phosphorus-deficit? A systematic map protocol

BackgroundThere is an urgent need to ensure that food production is maintained in response to either a reduction in use or lack of availability of natural resources. To this end, several strategies have been investigated to determine which agronomic approaches may improve crop yields under conditions of reduced water and/or nutrients provision, with special attention upon nitrogen (N) and phosphorus (P). New technologies and practices have been developed for key commercial crops, such as tomatoes. However, few of these are widely adopted in the field and evidence of their value in this production setting is limited.MethodsThis protocol sets out a systematic map methodology that aims to provide a coherent synthesis of the available evidence among the literature on the techniques and management approaches that may ensure the productivity of field-grown tomatoes under conditions of water-, N- and/or P-deficits, either as single or combined stresses. To conduct the literature search, a search strategy was produced to define the scope of the systematic map and to allow reproducibility of the approach. A list of published and unpublished sources of literature were selected and a preliminary trial identified best-fit-for-purpose search-terms and -strings. A literature screening process was set with consistency checks amongst reviewers at the title, abstract and full text screening stages. A series of eligibility criteria were defined to ensure objectivity and consistency in the selection of studies that are best suited to address the research question of the systematic map. In addition, a coding strategy was designed to set the means for meta-data extraction out from the literature for review. A drafted structured questionnaire will serve as the base for collating the meta-data to produce a database where variables will be queried for the evidence synthesis. This work is expected to inform stakeholders, researchers and policy makers regarding the extent and nature of the existing evidence base, and so serve as a basis by-which specific approaches may be highlighted as potential focal-areas in future.

High Energy, Sub-Cycle, Field Synthesizers

Tailoring the electromagnetic field transients has been a prominent research focus over the last decade. Advances in ultrashort pulse generation and stabilizing the carrier phase of the electromagnetic field relative to its envelope allowed for extension of coherent synthesis to optical frequencies and ultrashort pulse domain at tens of microjoules of energy. In parallel, ytterbium-doped lasers become a mature technology. They are able to deliver down to 1-picosecond scale pulses at hundreds of millijoule energy and kilowatt-scale average power, making them suitable frontends for scaling the energy and power of light transients. In this paper, we discuss two conceptual schemes, our experimental results, and technological challenges for generation of sub-cycle light transients based on Yb:YAG thin-disk lasers by direct and efficient spectral broadening of ytterbium-doped lasers, and by coherent combination of pulses from multiple broadband optical parametric amplifiers. Moreover, a conceptual design study for a novel synthesis scheme based on polarization splitting of a broadband spectrum and amplification of each polarization in a separate stage is presented. The novel sources hold promise for studying and controlling the nonlinear interactions of matter with custom-tailored light transients at a sub-cycle period of their electric field, opening up unprecedented opportunities in attoscience and strong-field physics.

Generation of few-cycle laser pulses by coherent synthesis based on a femtosecond Yb-doped fiber laser amplification system

We demonstrate a coherent synthesis system based on femtosecond Yb-doped fiber laser technology. The output pulse of the amplification system is divided into two replicas and seeded into photonic crystal fibers of two parallel branches for nonlinear pulse compression. Because of the different nonlinear dynamics in the photonic crystal fibers, the compressed pulses show different spectra, which can be spliced to form a broad coherent spectrum. The integrated timing jitter between the pulses of two branches is less than one tenth of an optical cycle. By coherently synthesizing pulses from these two branches, 8 fs few-cycle pulses are produced.

Spiral spectrum analysis and application ofcoherent synthetic vortex beams

The vortex beam is a ring-shaped beam whose center intensity or axial intensity is zero in the propagation direction and whose phase has a spiral rising or falling gradient distribution, which is also called a dark hollow beam. Vortex beams have important applications in free-space optical communication, optical micromanipulation, quantum information processing, optical measurement, super-resolution imaging, laser processing, and material processing. In recent years, with the in-depth research on vortex beams, the application requirements for high-power vortex beams also increase. High-power and high-quality vortex beam can be obtained by coherent combining technology. However, the spiral spectrum characteristics of the vortex beam generated by coherent combining technology need further exploring. In this paper, based on the theory of spectral analysis, we derive the position and magnitude of the spiral phase spectral component of the coherent synthetic vortex beam. The numerical results verify the correctness of the theoretical derivation. Based on the above spectral analysis theory, the mode purity of the target synthesis topology charge can be used as the evaluation function to evaluate quality and optimize the parameters for the coherent synthetic vortex beam, and then to quantitatively guide the coherent synthesis of the vortex beam. The results show that with the increase of the number of sub-beams and the radius of the beam waist of the source plane, the reduction of the radius of the bundle ring and the mode purity of the target synthesis topology charge can be improved, and then we can obtain the high-quality vortex beam. This is consistent with the conclusion obtained by using traditional evaluation functions such as power in the bucket. The spiral spectrum analysis of the coherent synthetic vortex beam not only makes up for the lack of evaluation of the spiral phase synthesis effect by the traditional evaluation function, but also has certain reference significance for understanding the nature of the coherent synthesis technique.

父脉冲参数对飞秒脉冲相干合成质量的影响

父脉冲参数对飞秒脉冲相干合成质量的影响

Generation of 3.9-cycle pulses from the coherent synthesis of two continuous-wave injection seeded optical parametric amplifiers at 53 MHz.

A high repetition-rate, few-cycle light pulse is of great importance due to its potential for a variety of applications, including two-dimensional infrared spectroscopy and time-resolved imaging of molecular structures, which benefit from its ultrabroadband spectrum and ultrashort pulse duration. The generation of an ultrabroadband coherent spectrum is one of the frontiers of ultrafast optics, and accessing such few-cycle pulses is presently under active exploration. Here, we demonstrate a simple yet effective pulse synthesizer. It is based on two continuous-wave (cw) injection-seeded high-repetition-rate optical parametric amplification systems and the following self-phase-modulation dominated spectra-broadening processes. The combined spectrum spans from 1250 to 1670nm, and a near Fourier-transform-limited 3.9-cycle (19.2fs) synthesized pulse with a central wavelength of 1470nm is obtained accordingly.

An Emerging Archaeology of the Nazi Era

The archaeology of the Nazi era is a relatively new field of research. This review addresses motivations and ethical circumstances of such research, as well as the complex relations between archaeological evidence and a variety of other sources, including documents, oral history, and photography. Archaeologists work with two fundamentally different conceptualizations: an objectivist one concerned with recording material remains, for which scale is a prominent issue, and interpretive approaches based on the evocative power of things, in which different degrees of victims’ anonymity play a core role. Other issues involve questions about the possibility of any coherent synthesis of this period. Investigations into the Nazi past also invariably include commemorative politics whose complex development is outlined. An engagement with this time of extremes has wider consequences, posing the question of the role of suffering and desolation in human history as a whole.

Optical response mediated by a two-level system in the hybrid optomechanical system

The optical response is studied in a hybrid nanomechanical system which is that a superconducting qubit is coupled with the mechanical mode. We show that the system displays the phenomena of the coherent perfect photon reflection, transmission, absorption, and synthesis. The qubit–mechanical interaction can lead to significantly modified optical response properties and provide a new interference channel for the optical response and add an additional perfect transmission, reflection, absorption, or synthesis point in such a hybrid system. This work may open up the hybrid optomechanical system as a perfect reflector, transistor, absorber, and synthesizer for the study of optical switch in the future quantum networks.

Coherent Control of a Plasmonic Nanoantenna Integrated on a Silicon Chip

Illuminating a plasmonic nanoantenna by a set of coherent light beams should tremendously modify its scattering, absorption, and polarization properties, thus, enabling all-optical dynamic manipulation. However, diffraction inherently makes coherent control of isolated subwavelength-sized nanoantennas highly challenging when illuminated from free-space. Here, we overcome this limitation by placing the nanoantenna at a subwavelength distance of the output facet of silicon waveguides that provide monolithically defined paths for multibeam coherent illumination. Inspired by coherent perfect absorption (CPA) concepts, we demonstrate experimentally modulation of the nanoantenna scattering by more than 1 order of magnitude and of the on-chip transmission by >50% over a ∼200 nm bandwidth at telecom wavelengths by changing the phase between two counter-directional coherent guided beams. Moreover, we demonstrate coherent synthesis of polarization of the radiated field by illuminating the nanoantenna from orthogona...

Framework for Conducting and Writing a Synthetic Literature Review

The framework presented in this article supports researchers in translating the copious information gleaned from the research literature into a coherent synthesis and critical analysis of the state of knowledge on the topic, identification of gaps and inconsistencies in the body of research, and recognition of the next logical steps in the line of research inquiry. The framework sequence guides the researcher in a step-by-step fashion from selecting the research literature to be reviewed to analyzing the studies, identifying the patterns and trends in the literature, writing the literature review narrative, and drawing conclusions and implications. The framework approach ensures that the literature review will reflect the quality indicators expected of this kind of research whether the end product is the rationale for an empirical study or a freestanding synthetic literature review.

Photonic coherent perfect transmission, absorption, and synthesis in a bimodal cavity quantum electrodynamics system

In this paper, we investigate an optical hybrid system in which a single quantum emitter is coupled to both modes of a bimodal optical microcavity, and propose a scheme for coherent perfect transmission, coherent perfect absorption, and coherent perfect synthesis of optical photons by utilizing such a bimodal cavity quantum electrodynamics (QED) system. In the present scheme, each mode of the bimodal microcavity can be coherently driven by an external monochromatic continuous-wave driving laser and the two cavity modes are not directly coupled to each other due to their orthogonal polarizations. It is found that three important phenomena, i.e., photonic coherent perfect transmission, absorption, and synthesis can be achieved in the optical hybrid system under appropriate conditions. We discuss in detail the theoretical model and present results of numerical simulation of the system in the steady state with experimentally achievable system parameters. Also, the possible experimental realization of the scheme in a solid-state approach is analyzed based on the semiconductor quantum dot and the photonic crystal defect microcavity. This study may provide further insight into the understanding of bimodal cavity QED system and find potential applications in quantum information processing and future quantum networks.

Coherent synthesis of ultrashort pulses based on balanced optical cross-correlator

Coherent synthesis of laser pulses is a major trend in the generation of ultrafast pulse field. There is no good way to compensate for the whole spectrum when the spectrum of ultrashort pulses is wide enough to reach an octave, so it is difficult to realize a sub-cycle pulse in a single-path laser system even if the spectrum range is wide enough. In this paper, 0.8 mJ, 30 fs laser pulses at 1 kHz repetition rate with 790 nm center wavelength from a Ti:sapphire chirped pulse amplifier (CPA) system are focused into hollow fiber with an inner diameter of 250 μm and a length of 1 m to produce an octave-spanning white-light supercontinuum (450-950 nm). Using this supercontinuum, we conduct two sets of comparative experiments. 1) We split the supercontinuum into two pulses with different spectrum ranges (450-750 nm and 650-1000 nm) by a dichroic mirror (HR, 500-700 nm; HT, 700-1000 nm), and we compress the two pulses by the double-chirped mirrors and wedge pairs to generate two few-cycle pulses:the long and short wavelength yielding pulses are 7.9 fs and 6.1 fs, respectively. Then we coherently synthesize two pulses by using another dichroic mirror, and controlling the relative time delay between the two pulses, and thus we synthesize a pulse of 4.1 fs. 2) We directly compress the supercontinuum by the double-chirped mirrors and wedge pairs, and obtain an optimization result of 5.3 fs, of which the pulse duration is wider than that in experiment 1. In these comparative experiments, the advantage of coherent synthesis for shorter pulse duration is preliminarily verified. Besides, the balanced optical cross-correlator technique is used to lock the relative time delay between two pulses. The root-mean-square value of relative time delay drift is less than 80 as in the case with feedback control loop, which ensures the stability of coherent synthesis system. This scheme can be adopted to accurately compensate for the dispersion and obtain the sub-cycle synthesized pulse, which is useful for generating the high harmonic and atto-second pulse.

Mulla Sadra by Ibrahim Kalin

Reviewed by: Mulla Sadra by Ibrahim Kalin Edward Moad (bio) Mulla Sadra. By Ibrahim Kalin. Oxford: Oxford University Press, 2014. Pp. 192. Paperback $24. isbn: 978-0-19-945117-3. This introduction to the life and thought of Muhammad ibn Ibrahim ibn Yahya Qawami al-Shirazi (Sadr al-Din al Shirazi, or Mulla Sadra), is part of the Makers of Islamic Civilization series, conceived by the Oxford Centre for Islamic studies, edited by Farhan Nizami, and published by Oxford University Press. The self-described aim of the series is to provide a set of introductory texts on outstanding figures in the history of Islamic civilization. This volume represents an important contribution to the literature on a neglected period of Islamic philosophy, by a scholar who is emerging as one of the most important contemporary Muslim thinkers. Ibrahim Kalin states his own aims in the book in terms of its four main chapters. The first is to give a brief account of Mulla Sadra's life and influence. The second is to describe the cultural and intellectual context in which his thought developed. The third is to introduce Sadra's main intellectual contribution: his doctrine of the primacy of existence. The fourth provides an overview of Sadra's thought and assesses the extent to which it succeeded (or not) in arriving at a coherent synthesis." (p. 9) Kalin thoroughly accomplishes the first two of these objectives. He does a great job of putting Mulla Sadra in historical context, including the preceding rise of the Safavid dynasty with Shah Ismaʿil's conversion of the Safawiyya Sufi order from Sunnism to Twelve-Imam Shiʿism in 1501. Sadra emerges a generation later, as a major intellectual at the beginning of Shi'a ascendency in Iran. Kalin provides a clear and readable account of the intellectual climate of the time, including the akhbari-usuli controversy and the emergence of a new Shʿia oriented Sufism. He shows how the work of Sadra emerged out of a bubbling cauldron of diverse ideas, including the peripatetic philosophy of Al-Farabi and Ibn Sina, the ishraqi school of Suhrawardi, the Sufi metaphysics of Ibn ʿArabi, and the various schools of Shiʿʿa and Sunni kalam. He is also generous in describing Sadra's influence on future thinkers. Unfortunately, Kalin is not as successful with his fourth objective, of providing a critical assessment of the success of Sadra's overall project; and the reason for this seems to be that the way he approached the third objective, of introducing the 'primacy of existence' doctrine, upon which the success of [End Page 1] Sadra's project turns, was not such as to make a critical assessment possible. That need not necessarily detract from the book, because there is some reason to believe that the doctrine itself is simply not accessible to critical assessment, at least of any sort that can be accomplished in a book. As Kalin puts it: For Sadra, one of the goals of philosophy is to equip us with the proper epistemic tools and cognitive means to 'see' the self-evident (badihi) reality of existence. This, however, cannot be achieved by mental or rational analysis alone because demonstrative and rational analyses give us only a mental picture of existence, not its reality. (p. 82) But there is some ambiguity on this point, which first appears in Kalin's account of Sadra's view of the relation between ʿirfan, and burhan. On the one hand, he says that "gnosis is not without cognitive content, and a true sage can explain his vision by using ordinary rational arguments." (p. 47). On the other, he quotes Sadra as saying "the knowledge of what is tasted and the knowledge of spiritual states cannot be captured in the garment of letters and words." (p. 49). The latter position lends itself to Wittgenstein's famous dictum, "that of which we cannot speak we must pass over in silence." But the former characterization of Sadra's position, and the fact that he did have a lot to write on the primacy of existence, whets the appetite for a satisfying burhani treatment of the topic; one that, as Kalin puts it, "ensures that...