Degree Of Coherence Research Articles

Dynamical evolution of a five-level atom interacting with an intensity-dependent coupling regime influenced by a nonlinear Kerr-like medium

We present an analytical solution for a quantum system characterized by a double Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda$$\\end{document} five-level atom interacting with an intensity-dependent coupling regime, influenced by a nonlinear Kerr-like medium. We also derive the constants of motion through Heisenberg’s equations. Furthermore, the dynamical evolution of the entanglement and quantum coherence between the atom and the field is discussed using linear entropy and l1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$l_{1}$$\\end{document}-norm of coherence. Through a comprehensive examination of the quantum system, it is observed that both the detuning and the Kerr-like parameters exert a significant impact on the degree of entanglement and coherence. However, the impacts of detuning and the Kerr effect become less pronounced when the photon multiplicity is high. In addition, we conduct a comparison between the five-level atomic system and a four-level system, revealing that the number of energy levels has a profound impact on the behavior of entanglement and coherence. These findings highlight the importance of atomic structure and photon multiplicity in controlling and optimizing quantum processes, particularly in applications involving quantum communication and information processing.

Firing patterns transitions and resonance effects of the extended Hindmarsh-Rose neural model with Gaussian noise and transcranial magneto-acousto-electrical stimulation

Considering the fact that the typical three-variable Hindmarsh-Rose(HR) neural model has limitations in describing the complex non-linear features and precise behavior patterns of neuron, the influences of transcranial magneto-acousto-electrical stimulation(TMAES) on firing patterns and resonance effects are analyzed based on an extended HR neural model in this paper. Obtained results show that TMAES can induce transitions in the firing patterns of extended HR neuron, such as spiking and multi-periodic bursting state, etc If appropriate parameters are selected, the multimodal discharge modes can also be observed. Coefficient of variation is calculated to further investigate the effect of TMAES and Gaussian white noise on the firing rhythm of extended HR neuron, and relevant results indicate that TMAES can induce coherent resonance phenomena in HR neuronal systems similar to the effects of Gaussian white noise, which reveals a new mechanism of coherent resonance induced by TMAES. Further more, TMAES can also regulate coefficient of variation to exhibit anti-coherent resonance and multiple anti-coherent resonance structures, exhibiting richer regulatory functions than Gaussian white noise in regulating neuronal firing rhythm. This study seeks to enhance the understanding of the processes that influence the firing patterns and coherence degree of neuron under TMAES in neuroses or psychoses.

Measuring, processing, and generating partially coherent light with self-configuring optics

Optical phenomena always display some degree of partial coherence between their respective degrees of freedom. Partial coherence is of particular interest in multimodal systems, where classical and quantum correlations between spatial, polarization, and spectral degrees of freedom can lead to fascinating phenomena (e.g., entanglement) and be leveraged for advanced imaging and sensing modalities (e.g., in hyperspectral, polarization, and ghost imaging). Here, we present a universal method to analyze, process, and generate spatially partially coherent light in multimode systems by using self-configuring optical networks. Our method relies on cascaded self-configuring layers whose average power outputs are sequentially optimized. Once optimized, the network separates the input light into its mutually incoherent components, which is formally equivalent to a diagonalization of the input density matrix. We illustrate our method with numerical simulations of Mach-Zehnder interferometer arrays and show how this method can be used to perform partially coherent environmental light sensing, generation of multimode partially coherent light with arbitrary coherency matrices, and unscrambling of quantum optical mixtures. We provide guidelines for the experimental realization of this method, including the influence of losses, paving the way for self-configuring photonic devices that can automatically learn optimal modal representations of partially coherent light fields.

Highly coherent mid-infrared wideband supercontinuum generation by a silica cladded silicon nitride core buried waveguide

Abstract Optical waveguides with semiconductor cores are drawing considerable research interest in the domain of supercontinuum (SC) generation in recent times. In this work, we design a square-core silicon nitride buried waveguide with a silica-clad, aiming for a wideband spectrum generation in the mid-IR region when operated at the standard telecommunication wavelength of 1550 nm. Among different such silicon nitride square-core buried waveguides, we propose a typical design with dimensions of 400 nm × 400 nm along its height and width, capable of producing a highly coherent broadband intensity spectrum ranging from 810 nm to 5441 nm after propagating through just a few millimeters of the waveguide. The group velocity dispersion maintains minimal value over a broad wavelength range in the mid-IR region, while the nonlinear coefficient is estimated to be sufficiently high. The nonlinear pulse propagation through such a waveguide leads to achieving an SC spanning over 2.76 octaves, sufficiently broader than previously reported silicon nitride-based waveguides. Furthermore, our calculations confirm the highly coherent nature of the generated SC. To the best of our knowledge, this is the first report of SC generation maintaining a high degree of coherence over such a wide wavelength range in the mid-IR zone using a square-core silicon nitride buried waveguide.

A comprehensive analysis of the spectroscopic and drug-like properties of dimethyl 5-hydroxybenzene-1,3-dicarboxylate: insights from DFT and MD simulations

ABSTRACT An in-depth investigation was undertaken to explore the ground-state molecular and electronic structure of Dimethyl 5-hydroxybenzene-1,3-dicarboxylate (D5HD). The potential energy scan of D5HD at various dihedral angles identified the lowest energy conformer, which was re-optimised at the higher basis set. The recorded FT-Raman and FT-IR spectra were compared with corresponding theoretical spectra, demonstrating a high degree of coherence. A comprehensive Natural Bond Orbital analysis was done for D5HD to gain insights for the overall electronic distribution within the molecule. Additionally, nonlinear optical (NLO) properties along with various DFT-based descriptors were calculated. Molecular docking studies against human acetylcholinesterase enzyme (PDB 2JF0), D5HD displayed good binding affinity. The study revealed that hydrogen bonded as well as van der Waals interactions exist between D5HD and different residues in the binding cavity of the target protein. The 100 ns MD simulation confirms the conformational stability of protein (2JF0)–ligand (D5HD) complex. The binding energy and residue decomposition analysis performed using MM-GBSA approach showed positive results with binding energy of −17.76 kcal/mol. Furthermore, D5HD effectively passed all pharmacokinetic filters, establishing its potential as a promising candidate in the quest for novel acetylcholinesterase inhibitors. Highlights Systematic exploration of the structure and spectroscopic properties of D5HD. Molecular docking between D5HD and acetylcholinesterase (PDB 2JF0) reveals the establishment of hydrogen bonds and Van der Waals interactions. D5HD successfully complies with all relevant pharmacokinetic filters. MD simulation analysis on 2JF0–D5HD complex confirms the conformational stability. Energy and residue decomposition based on MMGBSA approach.

OAM degree of coherence.

A new, to the best of our knowledge, scalar quantity characterizing radial correlations among all the orbital angular momentum (OAM) modes present in a random beam is introduced. It is given by the maximum value of the interference fringe contrasts produced by the filtered pairs of the OAM modes. This new measure is termed the OAM degree of coherence (DOC) in similarity with the electromagnetic (EM) degree of coherence which describes two-point correlations in polarization components of the electric field. The theoretical development is augmented by several numerical examples. Moreover, the possibility of combining the OAM and the EM degrees of coherence in one quantity is also outlined.

Prime number factorization and degree of coherence of speckled light beams.

We discover a connection between a Gauss sum of number theory and the degree of coherence (DOC) of the field in a transverse plane of structured speckled light beams. We theoretically demonstrate and experimentally validate that prime number factorization can be achieved by manipulating the source beam's DOC in Young's double-slit experiment. The determination of whether a number can be factored is based solely on the visibility of the resulting interference patterns. Our findings offer new insights into information encryption and decryption, data compression, etc.

The ingredients for spreading tourism culture

The importance of spreading tourism components lies in identifying these tourism structures and trying to use them. This is to raise the cultural level of the population towards tourism culture and raise the level of tourism culture in a way that treats tourists properly without distorting the culture of the host country. The aim of this study is to identify the factors for the Spreading the elements of tourism and defining society is crucial for building a tourism industry in developing nations, which is seen as a valuable economic resource. The research has two sides: theoretical and operational, and the descriptive analytical approach was applied. Theoretically, reference was made to numerous publications and academic theses that had been written specifically to the factors contributing to the rise of tourist culture. Regarding the operational element, a questionnaire was created and given to a random sample of guests in both these hotels and tourist areas. To gauge the questionnaire's stability, Cronbach's alpha was used. The study questionnaire was next examined for the presence of internal stability (credibility), which demonstrates the degree of coherence or correlation between the questionnaire's paragraphs. In order to determine whether the study's assumptions of which indicates that (there is an importance of the components in spreading the tourism culture) and another of which argues that (there is a statistically significant relationship between the components and the tourism culture). The research produced a number of recommendations and conclusions, the most significant of which was that the desire to promote tourism awareness and culture is one of the prerequisites for the development of tourism infrastructure because it is practically impossible to discuss the growth of the tourism industry without a high level of public awareness of the industry. The creation of a national center or institute for the dissemination of tourism culture, which develops educational programs and studies for the community, workers, and those involved in the tourism sector, is one of the most crucial recommendations. This will help everyone, especially the residents of Sulaymaniyah governorate, understand the significance of tourism culture.

Heterodyne coherent detection of the electric field temporal trace emitted by frequency-modulated comb lasers

Frequency-modulated (FM) combs are produced by mode-locked lasers in which the electric field has a linearly chirped frequency and nearly constant amplitude. This regime of operation occurs naturally in certain laser systems and constitutes a valuable alternative to generate spectra with equidistant modes. Here, we use a low-noise fs-pulse comb as the local oscillator and combine dual comb heterodyne detection with time domain analysis of the multi-heterodyne signal to reveal the temporal trace of both amplitude and phase quadratures of FM comb lasers’ electric field. This technique is applied to both a dense and a harmonic mid-infrared free-running quantum cascade laser frequency comb and shows direct evidence of the FM behavior together with the high degree of coherence of these sources. Our results furnish a deeper insight on the origin of the FM combs and pave the way to further improvement and optimization of these devices.

Reconstructing the spatial structure of quantum correlations in materials

Quantum correlations are a fundamental property of quantum many-body states. Yet they remain experimentally elusive, hindering certification of genuine quantum behavior, especially in quantum materials. Here we show that the momentum-dependent dynamical susceptibility measured via inelastic neutron scattering enables the systematic reconstruction of a general family of quantum correlation functions, which express the degree of quantum coherence in the fluctuations of two spins at an arbitrary mutual distance. Using neutron scattering data for the compound KCuF3—a system of weakly coupled S=1/2 Heisenberg chains—and numerically exact quantum Monte Carlo data, we show that quantum correlations possess a radically different spatial structure with respect to conventional correlations. Indeed, they exhibit a different emergent length scale—the quantum coherence length—which is finite at any finite temperature (including when long-range magnetic order develops). Moreover, we show theoretically that coupled Heisenberg spin chains exhibit a form of quantum monogamy, with a trade-off between quantum correlations along and transverse to the spin chains. These results highlight real-space quantum correlators as an informative, model-independent means of probing the underlying quantum state of real quantum materials. Published by the American Physical Society 2024

A fresh look at the Gulf of St. Lawrence, Eastern Canada: Geophysical imaging of salt bodies and volcanic rocks in the upper Paleozoic Magdalen Basin

In the Gulf of St. Lawrence, the late Middle Devonian to early Permian Magdalen Basin hosts numerous salt bodies, but their number and geometry remained poorly constrained due to the poor quality of industry-seismic data. Salt originates from the Middle Mississippian (Visean) Windsor Group, which includes marine carbonates and evaporites. In this study, we use multibeam bathymetry as well as unpublished aerogravity and aeromagnetic data to better characterize the geometry of salt bodies. These datasets show a high degree of coherency and illustrate deformation on the seafloor, gravity lows and magnetic highs, all associated with salt bodies and overlying volcanic rocks. In map view, the geometry of individual salt bodies varies from nearly circular to ovoid and strongly elongated. Some salt bodies coalesce in complex-shaped salt walls elongated NNE, parallel to some of the faults that controlled the early stages of the Magdalen Basin development. Forward modeling indicates that low density salt bodies overlain by a 100–300 m thick volcanic pile may account for both gravity and magnetic signals. The ubiquity of mafic volcanic rocks indicates that the late Visean to Serpukhovian volcanic episode is more voluminous than previously thought. This episode is possibly associated with a series of dykes continuous for up to 225 km and with a period of underplating now recorded by a lower crustal layer with high seismic velocity.

The Spatiotemporal Matching Relationship between Metro Networks and Urban Population from an Evolutionary Perspective: Passive Adaptation or Active Guidance?

With the operation of the first route in Xi’an City, the matching relationship between the metro networks and the urban population is a root factor affecting the utilization of rail transit facilities. The mismatch between the metro networks and the urban population has led to an imbalance between the supply and demand for rail transport, resulting in wasted urban infrastructure. Based on this issue, the research objective is to focus on the spatiotemporal variations of the matching relationship. Firstly, the topological network model abstractly extracted metro spatial distribution features, and the spatial autocorrelation model was adopted to identify the evolution characteristics of the metro networks and urban population. Secondly, this paper adopted a time-lagged regression model to demonstrate the action relationship from 2011 to 2021. Then, the compositive coordination index was utilized to assess the variation of the global matching relationship. Finally, the paper explored spatial heterogeneity through the coupling coherence degree attached to grid cells. The research results indicate that the Moran’s I value of metro elements decreased from 0.782 to 0.510 with the further complexity of topological networks, while the population was consistently high in spatial dependence with a Moran’s I value of around 0.75 during the decade. Based on the regression coefficients and significance, this paper verified the hypothesis that the metro networks and urban population had a positive time-lagged feedback effect in urban development. From 2011 to 2021, the compositive coordination index symbolizing the global matching relationship increased from 0.29 to 0.90, but the coupling coherence degree shows significant spatial heterogeneity in different grid units. Differentiated spatial planning strategies were proposed for varied areas to efficiently utilize rail transit, which may provide a reference for other cities with the same reality problem.

Partial coherence enhances parallelized photonic computing

Advancements in optical coherence control1–5 have unlocked many cutting-edge applications, including long-haul communication, light detection and ranging (LiDAR) and optical coherence tomography6–8. Prevailing wisdom suggests that using more coherent light sources leads to enhanced system performance and device functionalities9–11. Our study introduces a photonic convolutional processing system that takes advantage of partially coherent light to boost computing parallelism without substantially sacrificing accuracy, potentially enabling larger-size photonic tensor cores. The reduction of the degree of coherence optimizes bandwidth use in the photonic convolutional processing system. This breakthrough challenges the traditional belief that coherence is essential or even advantageous in integrated photonic accelerators, thereby enabling the use of light sources with less rigorous feedback control and thermal-management requirements for high-throughput photonic computing. Here we demonstrate such a system in two photonic platforms for computing applications: a photonic tensor core using phase-change-material photonic memories that delivers parallel convolution operations to classify the gaits of ten patients with Parkinson’s disease with 92.2% accuracy (92.7% theoretically) and a silicon photonic tensor core with embedded electro-absorption modulators (EAMs) to facilitate 0.108 tera operations per second (TOPS) convolutional processing for classifying the Modified National Institute of Standards and Technology (MNIST) handwritten digits dataset with 92.4% accuracy (95.0% theoretically).

Perfect correlation vortices.

We introduce perfect correlation vortices and show that the degree of coherence of any such vortex at the source is nearly statistically homogeneous and independent of the topological charge of the vortex. We demonstrate that while slowly diffracting in free space, perfect correlation vortices maintain their "perfect" vortex structure; they are capable of preserving said structure even in strong atmospheric turbulence. Structural resilience to diffraction and turbulence sets the discovered perfect vortices apart from their coherent cousins and makes them suitable for free-space optical communications.

Climate dynamics and the effect of topography on snow cover variation in the Indus-Ganges-Brahmaputra river basins

The river basins of the Indus-Ganges-Brahmaputra (IGB) are characterized by rapid population growth, increased water demand, and rapid snow/ice melting, all of which combine to make these catchments especially vulnerable to climate change. Here, we present a comprehensive dataset (2003−2020) for precipitation, temperature and snow cover area (SCA) to investigate the spatio-temporal variability of important climate factors in relation to elevation and across three major sub-basins of the IGB. Improved MODIS (Moderate Resolution Imaging Spectro-radiometer) Terra and Aqua snow cover data are used to estimate regional snow cover, while Climate Hazards Group InfraRed Precipitation with Station Data version 2.0 (CHIRPS-V2.0) is deployed for precipitation, and MODIS Land Surface Temperature (LST) data are used to estimate temperature. The analysis reveals significant changes in precipitation, LST and snow cover throughout the IGB region together with a strong degree of spatial coherence between SCA and regional surface topography (R2 = 0.82).Maximum changes were observed in the Brahmaputra basin at mean annual precipitation (13.9 mm/year) and reduced SCA (155.4 km2/year) over the period studied. Similar trends are also evident, albeit with relatively lower absolute values in the other two basins, whereby the Indus basin evidences a significant reduction in annual SCA, averaging 82.2 km2/year with increased precipitation (3.12 mm/year) and LST. This investigation further highlights the relative influence of climate change factors and regional human activities in determining high-elevation changes in SCA. Most of the middle elevation regions of the Ganges experienced a significant reduction in SCA, with human impact contributing 82% of the observed variation, while climate factors are more prominent in the Indus and Brahmaputra basins. Understanding the dynamics of snow cover and its regional influencing factors is crucial to the more accurate evaluation of water resources and to defining appropriate mitigation and adaptation strategies for the coming decades.

Single-modulator, dual comb serrodyne spectroscopy.

Dual optical frequency comb spectroscopy allows for high speed, broadband measurements without any moving parts. Here, we combine differential chirp downconversion to probe large spectral bandwidths and serrodyne modulation to separate the positive and negative sidebands in a single modulator. As an initial demonstration, we apply this approach to measure a sharp cavity resonance to illustrate the system performance. We then measure methane transitions in the near-infrared and compare the resulting spectra to models based upon the current spectroscopic databases. The serrodyne method has lower hardware requirements compared to many existing approaches, and its simplicity enables a high degree of mutual coherence between the two combs. Further, this method is readily amenable to chip-scale photonic integration.

Scattering of the generalized multi-Gaussian correlated Schell-model beam upon a deterministic medium with semi-hard boundary

In this paper, based on the first-order Born approximation, the scope of scattering theory was broadened by analyzing the scattering of generalized multi-Gaussian correlated Schell-model (GMGCSM) beam upon a deterministic medium with semi-hard boundary. It was revealed that the scattering spectral density and degree of coherence (DOC) are affected by several parameters, covered semi-hard boundary medium’s summation index L and effective radius σR, and GMGCSM beam’s coherence length δ, index M and transverse width σ0. The valuable and meaningful results obtained here could contribute to the expansion of the application range of scattering theory, making it applicable in various fields such as optical communication, remote sensing, and medicine.

К ВОПРОСУ О ЦЕННОСТНО-СЕМАНТИЧЕСКОЙ РАЗНИЦЕ АВТОРСКИХ ПОДХОДОВ ПРИ ЛИТЕРАТУРНОЙ ОБРАБОТКЕ ПЕРВОЙ И ВТОРОЙ ЧАСТЕЙ ЭПИЧЕСКОЙ ПОЭМЫ «ДИГЕНИС АКРИТ»

The question of the correlation between the first and second parts of the Byzantine epic poem “Digenes Akritas” is still insufficiently covered in academic literature. Thus, for example, Byzantine scholars highlight both this work’s semantic-value integrity, and the fact that the folk songs serving as the basis of it had presumably been of diachronous nature. This determines the relevance of the poem’s axiological analysis, aiming to compare its parts with one another, as well as to clarify whether the artistic organization of “Digenes Akritas” involves a certain degree of inner unity and coherence. According to the present article, the famous Byzantine epic poem, when systematically studied in such a manner, reveals itself as a work implying a fundamental difference between its various plot-compositional parts. Examining the poem in terms of the heroes’ motivational values – which are, as a consequence, decisive for the plot, – we have identified eight axiomotifs (one for the introduction, three for the first part, and four for the second one) and analyzed them successively. The results are of obvious regularity. Thus, the poem’s first part – the one depicting the main hero’s parents – presupposes a Christian value perspective (i. e., a plot emphasis put on the categories of neighbor, compassionate love, and the glory of God), while the life story of the protagonist himself focuses on such individualistic unchristian concepts as personal fame and personal honor. Digenes, even if depicted in the poem as a man of faith, turns out to be motivated only by his own interests, and never acts selflessly for the sake of other people, religious shrines or the glory of God. As a result, it is possible not only to emphasize the fact that the epic in question has been created on the basis of different folk works, but also to establish that these works have been processed by at least two separate individuals – one of them a practicing Orthodox believer, while the other a person completely alien to Christian values – and combined mechanically only later. Consequently, an axiological analysis of the poem “Digenes Akritas” allows one to understand its genesis and its semantic-compositional structure in a more complete way, while creating prerequisites for similar studies of other Byzantine folk and literary epics, among them “The Tale of Belisarius”, “The Lay of Armouris”, and the more recent “Acritic Songs”.

Pixel-super-resolved lens-free quantitative phase microscopy with partially coherent illumination

Lens-free on-chip microscopy (LFOCM) has been widely utilized in digital pathology, drug screening, point-of-care testing (POCT), and quantitative phase imaging (QPI) due to its high throughput imaging capability and compactness. Initially, coherent laser sources were used in LFOCM to generate interference fringes to reconstruct the intensity and phase information of an object. The use of partially coherent light-emitting diodes (LEDs) in LFOCM offers a more portable and cost-effective alternative to conventional coherent illumination sources. However, the coherence-gating effect from a relatively low degree of coherence may cause a blur of high-frequency information in holograms, leading to an inaccurate object recovery. Thus, we present a pixel-super-resolved lens-free quantitative phase microscopy (PSR-LFQPM) with partially coherent illumination, which not only compensates for the impact of low coherence without increasing the volume of the system but also suppresses the theoretical Nyquist-Shannon sampling resolution limit imposed by the sensor pixel size (0.9 μm). Based on the partially coherent imaging model, we integrate the spatial coherence transfer function (SCTF) obtained from the pre-calibrated LED source distribution during the iteration process to obtain an accurate high-resolution recovery. Applying PSR-LFQPM to image living HeLa cells in vitro, we achieve real-time dynamic high-throughput QPI performance (half-pitch resolution of 780 nm with a 1.41-fold improvement compared to results without considering the effect of coherence) across a wide FOV (19.53 mm2). The proposed method provides a compact, low-cost, and high-throughput lens-free on-chip microscopy system for biomedical and POCT applications.

Differential phase-amplitude coupling in nucleus accumbens and orbitofrontal cortex reflects decision-making during a delay discounting task

BackgroundThe impulsive choice is characterized by the preference for a small immediate reward over a bigger delayed one. The mechanisms underlying impulsive choices are linked to the activity in the Nucleus Accumbens (NAc), the orbitofrontal cortex (OFC), and the dorsolateral striatum (DLS). While the study of functional connectivity between brain areas has been key to understanding a variety of cognitive processes, it remains unclear whether functional connectivity differentiates impulsive-control decisions. MethodsTo study the functional connectivity both between and within NAc, OFC, and DLS during a delay discounting task, we concurrently recorded local field potential in NAc, OFC, and DLS in rats. We then quantified the degree of phase-amplitude coupling (PAC), coherence, and Granger Causality between oscillatory activities in animals exhibiting either a high (HI) or low (LI) tendency for impulsive choices. ResultsOur results showed a differential pattern of PAC during decision-making in OFC and NAc, but not in DLS. While theta-gamma PAC in OFC was associated with self-control decisions, a higher delta-gamma PAC in both OFC and NAc biased decisions toward impulsive choices in both HI and LI groups. Furthermore, during the reward event, Granger Causality analysis indicated a stronger NAc➔OFC gamma contribution in the HI group, while the LI group showed a higher OFC➔NAc gamma contribution. ConclusionsThe overactivity in NAc during reward in the HI group suggests that exacerbated contribution of NAcCore can lead to an overvaluation of reward that biases the behavior toward the impulsive choice.