Wave Picture Research Articles

Phase stability of convergence zone propagation at mid-frequency.

Mid-frequency transmissions (1.5 to 7.5 kHz) from a towed source to a drifting array one convergence zone away demonstrate smoothly varying phase. Calculations of the strength and diffraction parameters Φ and Λ for a representative background environment predict partially saturated propagation. For a single convergence zone path, the evolving phase rate due to the changing internal wave field corresponds to a narrowband coherent integration time, defined by the length of a discrete Fourier transform that likely captures the signal, from ∼370 s at 10 kHz to ∼1370 s at 1 kHz in the absence of source motion. Simulated propagation with a split-step parabolic equation solver through a sound speed field with thermocline fine structure and a Garrett-Munk internal wave displacement field provides a full wave picture that is consistent with the statistical predictions. Experimental data from the Philippine Sea demonstrates signal phase that is highly correlated with source tow body vertical excursions, measured by a pressure sensor, that couple into horizontal motion. The received signal can be integrated for up to 128 s at 5.5 kHz, with the upper limit thought to be due to non-uniform source motion rather than ocean dynamics.

Shaping entangled photons through arbitrary scattering media using an advanced wave beacon

Entangled photons provide transformative new paths in the fields of communication, sensing, and computing. However, when entangled photons propagate through a complex medium, their correlations are scrambled. Using wavefront shaping to compensate for the scattering and retrieve the two-photon correlations is challenging due to the low signal-to-noise ratio of the two-photon signal. While previous works partly addressed this challenge by using feedback from a strong classical laser beam that co-propagates with the entangled photons, such methods frequently depend on assumptions about the complex medium, limiting the applicability of quantum wavefront shaping. In this work, we propose and demonstrate a new feedback mechanism that is inspired by Klyshko’s advanced wave picture: the classical laser beam is emitted in one of the detection modes, counter-propagates with one of the entangled photons, reflects at the crystal plane, and co-propagates with the other. The new Klyshko feedback allows compensation of scattering in arbitrary samples and even in situations where each photon propagates through a different scattering medium. Since the advanced wave picture applies whenever optical reciprocity is valid, such Klyshko optimization can be used across a wide range of configurations, offering a robust and alignment-free setup. We therefore believe this protocol will open the door for real-world applications of quantum wavefront shaping.

On the existence of Rayleigh waves with full impedance boundary condition

The existence of Rayleigh waves (propagating in isotropic elastic half-spaces) with the tangential and normal impedance boundary conditions was investigated. It has been shown that for the tangential impedance boundary condition (TIBC), there always exists a unique Rayleigh wave, while for the normal impedance boundary condition (NIBC), there exists a domain (of impedance and material parameters) in which exactly one Rayleigh wave is possible and outside this domain a Rayleigh wave is impossible. In this paper, we consider the existence of Rayleigh waves with the full impedance boundary condition (FIBC) that contains both TIBC and NIBC. It is shown that the existence picture of Rayleigh waves for this general case is more complicated. It contains domain for which exactly one Rayleigh wave exists, domain where a Rayleigh wave is impossible, and domain for which all three possibilities may occur: two Rayleigh waves exist, one Rayleigh wave exists, and no Rayleigh wave exists at all. The obtained existence results recover the existence results established previously for the cases of TIBC and NIBC. The formulas for the Rayleigh wave velocity are derived. As these formulas are totally explicit, they are very useful in various practical applications, especially in the non-destructive evaluation of the mechanical properties of structures. In order to establish the existence results and derive formulas for the Rayleigh wave velocity, the complex function method, which is based on the Cauchy-type integrals, is employed.

Impact of internal waves on underwater acoustic propagation

The propagation of internal waves in the ocean can produce significant fluctuations in the local sound speed field. Understanding how these fluctuations affect acoustic propagation is an area of considerable interest in underwater acoustics. Previous studies have indicated that large fluctuations (of the order of 20 dB) in transmission loss (TL) of acoustic waves can occur due to focusing and defocusing effects as the acoustic waves propagate through an internal wave. This work looks to extend some of these studies by exploring the frequency and directional dependence of these fluctuations through the implementation of a 3D acoustic model (FOR3D) suitable for modelling low frequency (<1 kHz) acoustic propagation. The study utilises sound speed data produced using the non-hydrostatic model MITgcm, simulating a nonlinear three-dimensional internal wave field that was verified using in situ mooring observations. By also considering results from a study utilising an acoustic ray model (Bellhop3D) on the same data, this work gives a comprehensive picture of the internal wave induced TL fluctuations across a range of acoustic frequencies.

Boreal Summer Extratropical Intraseasonal Waves over the Eurasian Continent and Real-Time Monitoring Metrics

Abstract Boreal summer extratropical intraseasonal oscillation (EISO) is crucial in modulating regional subseasonal variation and particularly causing extreme meteorological events, but it has yet to be well clarified and operationally monitored. This study first objectively sorts out three dominant EISOs trapped along two extratropical westerly jet streams over Eurasia, and then proposes the corresponding real-time metrics. The three dominant EISOs are (i) an 8–25-day eastward-propagating wave along the subtropical westerly jet (EISO-SJE) initiating at the exit of the North America–North Atlantic jet and strengthening over the Black Sea–Caspian Sea–arid central Asia region; (ii) a 10–30-day eastward-traveling wave along the polar front jet (EISO-PJE), starting near Scandinavia and enhancing from the East European Plain to the West Siberian Plain and then decaying over the Okhotsk region; (iii) a 10–40-day westward-migrating wave along the polar front jet (EISO-PJW), which enhances near the Ural Mountains and weakens over Scandinavia. The real-time metrics then, following the three EISOs, have been constructed, and they are able to capture the spatiotemporal features of three EISOs in application. Moreover, the close linkages between these EISOs and the regional extremes/the blocking occurrence have been clearly demonstrated, confirming the importance of real-time EISO metrics. Together with tropical intraseasonal oscillation, this study provides the subseasonal-to-seasonal (S2S) community with a well-portrayed unified picture of extratropical intraseasonal waves and the real-time metrics for monitoring boreal summer intraseasonal signals over Eurasia and facilitate subseasonal predictions. Significance Statement Boreal summer extratropical intraseasonal oscillation (EISO) has drawn increasing attention owing to its importance in triggering extreme weather events and affecting regional subseasonal prediction. However, despite the urgent need of the subseasonal-to-seasonal (S2S) community, a comprehensive delineation of EISO diversity and real-time EISO monitoring remain the gap of knowledge. This study objectively sorts out and comprehensively clarifies three dominant EISOs trapped along two extratropical westerly jet streams over Eurasia. More importantly, the well-portrayed real-time EISO metrics are constructed based on three EISOs, which are applicable for operational real-time monitoring, subseasonal prediction, and model evaluation. This study stimulates an extratropical focus in the S2S community as a complementary component in addition to monitoring the MJO’s teleconnection to the mid- to high latitudes.

Toward developing a comprehensive algorithm for solving kinetic plasma dispersion relations for parallel propagation with a kappa distribution

In general, it is challenging to numerically solve all the roots of plasma wave dispersion relations. The velocity distributions of multi-component particles in an anisotropic high-energy plasma can be better described by a drift loss-cone bi-Kappa distribution or a mixed drift loss-cone distribution containing bi-Kappa and bi-Maxwellian plasma in space and laboratories. In this work, we have developed a code with a new numerical algorithm to solve all roots of the kinetic dispersion relation for parallel propagation in hot magnetized plasmas with drift loss-cone bi-Kappa distribution. Solving all roots of the rational expansions of the kinetic dispersion relation is equivalent to a matrix eigenvalue problem of a linear system. We have performed detailed numerical solutions for three kinds of plasmas: bi-Maxwellian, bi-Kappa, and cold plasmas. We have also proposed a unified numerical method to solve the mixed dispersion relation based on the bi-Kappa and bi-Maxwellian distributions. The numerical results and benchmark studies demonstrate that the new algorithm is in agreement with the data from previous studies. This is a crucial step toward revealing a full picture of kinetic plasma waves and instabilities.

The noise sense effects on the characteristic nonlinearly Schrödinger equation solitary propagations

The nonlinearly stochastic Schrödinger equation (NLSSE) predicts the nonlinear process that produces the waves decay in many physics applications. The unified method has been used in obtaining different new stochastic forms for NLSSE damped by noises in Itô sense. The derived structures appear in the form of rational, solitons, soliton-like shocks, and explosive propagations. The new stochastic solutions investigated the change of frequencies by noise term in NLSSE in nonlinear process that may be produced in many nonlinear wave applications. Finally, wave picture properties may controlled by noise term in Itô sense effect, which gives new information’s for NLSSE in physics applications which is believed to be affected by the influence of Brownian motion that change the shape and structures of the generated decaying and damping waves.

Internal Solitary Waves in the White Sea: Hot-Spots, Structure, and Kinematics from Multi-Sensor Observations

A detailed picture of internal solitary waves (ISWs) in the White Sea is presented based on an analysis of historical spaceborne synthetic aperture radar (SAR) data and field measurements. The major hot-spot of ISW generation locates in the southwestern (SW) Gorlo Strait (GS), characterized by the presence of strong tides, complex topography, and two distinct fronts. Here, pronounced high-frequency isopycnal depressions of 5–8 m were regularly observed during flood and flood/ebb slackening. Other regions of pronounced ISW activity are found near Solovetsky Islands and in the northwestern Onega Bay. The spatial and kinematic properties of the observed ISWs are linked to water depth, with larger wave trains and higher propagation speeds being observed over the deep regions. Direct estimates of ISW propagation speeds from sequential and single SAR images agree well, while theoretical ones obtained using a two-layer model overestimate the observed values by 2–3 times. This is explained by the effective modulation of ISW propagation speed during the tidal cycle by background currents that are not accounted for in the model. Enhanced values of diapycnic diffusion coefficient in the pycnocline layer were registered near the frontal zones, where intense 14–17 m high ISWs were regularly observed.

Normalizing the brain connectome for communication through synchronization.

Networks in neuroscience determine how brain function unfolds, and their perturbations lead to psychiatric disorders and brain disease. Brain networks are characterized by their connectomes, which comprise the totality of all connections, and are commonly described by graph theory. This approach is deeply rooted in a particle view of information processing, based on the quantification of informational bits such as firing rates. Oscillations and brain rhythms demand, however, a wave perspective of information processing based on synchronization. We extend traditional graph theory to a dual, particle-wave, perspective, integrate time delays due to finite transmission speeds, and derive a normalization of the connectome. When applied to the database of the Human Connectome Project, it explains the emergence of frequency-specific network cores including the visual and default mode networks. These findings are robust across human subjects (N = 100) and are a fundamental network property within the wave picture. The normalized connectome comprises the particle view in the limit of infinite transmission speeds and opens the applicability of graph theory to a wide range of novel network phenomena, including physiological and pathological brain rhythms. These two perspectives are orthogonal, but not incommensurable, when understood within the novel, here-proposed, generalized framework of structural connectivity.

Transverse Traveling-Wave and Standing-Wave Ray-Wave Geometric Beams

Ray-wave geometric beam is an exotic kind of structured light with ray-wave duality and coupled diverse degrees of freedom (DoFs), which has attracted intense attention due to its potential applications in theories and applications. This work offers a new insight that the traditional ray-wave geometric beams can be seen as the transverse standing-wave (SW) beams, and can be decomposed into the superposition of transverse traveling-wave (TW) beams. We construct a generalized model for transverse TW and SW ray-wave geometric beams in the wave picture. In experiment, we exploit a digital hologram system with more flexible tunable DoFs to generate the transverse TW and SW beams, inspiring the exploration for the spatial wave structure of more complex structured light.

Characteristics of stochastic Langmuir wave structures in presence of Itô sense

This article focuses on the new wave structures for the system of equations for the ion sound and Langmuir waves (ISALWs) in plasma via stochastic sense. Namely, we consider this model damped by noises in Itô sense. The new presented stochastic solutions investigated the change of frequencies by noise term in nonlinear process that may be produced in many nonlinear wave applications. With the aid of Matlab release, some profile pictures were designed to illustrate the behavior of these solutions. These wave picture may controlled by noise term in Itô sense effects which gives new information’s for the system of equations for the ion sound and Langmuir waves in physics applications.

Traveling waves for a nonlocal KPP equation and mean-field game models of knowledge diffusion

We analyze a mean-field game model proposed by economists Lucas and Moll [J. Political Econ. 122 (2014)] to describe economic systems where production is based on knowledge growth and diffusion. This model reduces to a PDE system where a backward Hamilton–Jacobi– Bellman equation is coupled with a forward KPP-type equation with nonlocal reaction term. We study the existence of traveling waves for this mean-field game system, obtaining the existence of both critical and supercritical waves. In particular, we prove a conjecture raised by economists on the existence of a critical balanced growth path for the described economy, supposed to be the expected stable growth in the long run. We also provide nonexistence results which clarify the role of parameters in the economic model. In order to prove these results, we build fixed point arguments on the sets of critical waves for the forced speed problem arising from the coupling in the KPP-type equation. To this purpose, we provide a full characterization of the whole family of traveling waves for a new class of KPP-type equations with nonlocal and nonhomogeneous reaction terms. This latter analysis has independent interest since it shows new phenomena induced by the nonlocal effects and a different picture of critical waves, compared to the classical literature on Fisher–KPP equations.

A hierarchical decomposition of internal wave fields

Internal gravity wave fields are decomposed into temporal modes revealing the hierarchical structure of nonlinear wave–wave interactions. We present a novel fusion of Green's functions for solving the forced internal wave equation with a weakly nonlinear perturbation expansion. Our approach is semi-analytical, based on integration over finite elements with the perturbation expansion ensuring source terms at each order are only dependent on the solutions at lower orders. Thus, the procedure is purely inductive and efficient to compute. To perform a thorough validation of our new method, we diagnose experiments using synthetic Schlieren and apply sophisticated post-processing techniques, including dynamic mode decomposition, to obtain these temporal modes for systems with discrete input frequencies. By decomposing the experimental field and comparing individual constituents against equivalents synthesised by our model, we are able to present the first truly comprehensive, validated, mechanistic picture of wave–wave interactions to arbitrary order. This synergy enables us to identify non-wave oscillatory behaviour at frequencies shared by waves in the hierarchy and leads us to discover an important open question regarding transmission efficiency within individual wave–wave interactions. Although our experiments are generated by boundary displacements, we present equivalences between source terms and boundary displacements so that the class of applicable systems may be broadened. Our technique also generalises to aperiodic and unbounded configurations and to any weakly nonlinear wave-governed system for which there is an available Green's function.

The progress of gravitational wave detection in China and its further physical application

Contemporarily, a gravitational wave is one of the most important approaches to gather information from the enormous universe. In short, a gravitational wave is a wave that carries energy, and it is created by the acceleration of massive celestial body propagation with a speed of light. This paper discusses the recent progress of gravitational wave detection in China and clarifies our own opinion on future development. Specifically, a basic description is first presented about the definition and basic knowledge for gravitational wave models and detection methods. Subsequently, this section contains the plan and achievement of the Chinese gravitational wave observatory. Finally, the usages and applications of the gravitational wave to help to detect more phenomena in the universe are demonstrated. These results shed light on a clearer picture of gravitational waves, which may offer a better understanding of the background, principle of detection, and the uses of gravitational waves, i.e., emphasizes its importance in modern astrophysics scientific researches.

From Imbert–Fedorov shift to topologically spin-dependent walking off for highly confining fiber-guided twisted light

Light–matter interaction at dielectric interfaces usually manifests as spin-dependent correction to light propagation, known as classical Imbert–Fedorov (IF) shift or photonic spin Hall effect, ruled by the general spin–orbit interaction (SOI) of light. Even though vector wave equations and strong SOI-based perturbation theory in a wave picture can offer good solutions to describe the modal dispersion in optical fibers, it is difficult for all these to provide an intuitive insight into the walking off for twisted (or vortex) light beams carrying orbital angular momentum (OAM). Here we present a new perspective to the topologically spin-dependent modal splitting for the twisted light highly confined in optical fibers based on the classical IF shift on geometric optics. We verify this topologically IF-shift-based walking off by comparing the analytical results of modal splitting degrees with the solutions of eigen equation, and associate the longitudinal projection of IF shift with an interesting resonance of fiber Bragg gratings locked by the signs of SAM or OAM. This interpretation provides an insight supplement to describe light ray propagating in optical fibers together with both longitudinal Goos–Hänchen and transverse IF shift under the total internal reflection, and may benefit the development of nanoscale fiber-based light on optically classical or quantum communication and metrology.

Excitonic insulator emerging from semiconducting normal state in 1T−TiSe2

A new state of matter, an excitonic insulator (EI) state, was predicted to emerge from Bose-Einstein condensation of electron-hole pairs. Some candidate materials were suggested but it has been elusive to confirm its existence. Recent works gave renewed support for the EI picture of the charge density wave (CDW) state below the critical temperature $T_c \approx 200 $ K of $1T$-TiSe$_{2}$. Yet, an important link to its establishment is to show that a majority fraction of the measured $T_c$ indeed follows from the Coulomb interaction alone, while a quantitative match of the $T_c$ may require assistance from the electron-lattice coupling. This will establish that the CDW is formed predominantly by the Coulomb interaction and help confirm the EI view for TiSe$_2$. Here, we provide such calculations by solving the exciton gap equation with material specific electronic structures. We obtain, with no fitting parameters, $T_c \approx 135 \pm 27$ K for the normal state gap of $E_g \approx 74 \pm 15$ meV. It seems that the calculated $T_c$ from Coulomb interaction gives a majority fraction of experimental $T_c$ for recently determined values of $E_g$. The measured doping dependence of $T_c$ was satisfactorily reproduced as well. Also in agreement with experiments are the same set of calculations of the photoemission spectroscopy and density of states. The semiconducting state above and EI below $T_c$ together should give a coherent picture of $1T$-TiSe$_2$.

Real-time sub-wavelength imaging of surface waves with nonlinear near-field optical microscopy

Imaging evanescent waves is of crucial importance for sub-wavelength-scale investigation of various phenomena. However, frequently used techniques for near-field imaging require either a strong perturbation of the field, long acquisition times or complex electron-based tools. Here, we introduce nonlinear near-field optical microscopy (NNOM), which is capable of real-time evanescent wave imaging by nonlinear wave mixing while using only standard optical components. As a proof-of-concept, we present non-perturbative, single-shot mapping of evanescent plasmonic patterns, utilizing the nonlinearity of the host metal, and monitor in real time the externally controlled changes to the patterns. We further demonstrate the ability to extract the full field information—the amplitude and phase of all electric-field components—in a polarization-sensitive, spin-selective manner. This simple and highly tunable technique could be extended to deep sub-wavelength imaging of polaritons in two-dimensional materials or other nanophotonic guided modes, for swift photonic device characterization and optimized light−matter interactions. A near-field imaging approach based on nonlinear wave mixing that can provide a detailed picture of evanescent waves in real time and with a single shot is demonstrated. Using only standard optical components, this approach will make near-field imaging much more affordable and accessible.

Post-acceleration of electron bunches from laser-irradiated nanoclusters

In this paper the energy gain of attosecond electron bunches emitted during the interaction of intense, few-cycle linearly polarized lasers with nanoscale spherical clusters is determined. In this case electron bunches are emitted from the rear side of the cluster and are then further accelerated while co-propagating with the laser. A previous study has shown how this two-stage process readily occurs for clusters whose radii lie between the relativistic skin depth, δ r = γ 1/2 c/ω p , and the laser spot size σ L (Di Lucchio & Gibbon, Phys. Rev. STAB 18, 2015). An analytical model for focused light waves interacting with compact, overdense electron bunches in vacuum is derived heuristically from world-line equations of motion of an electron. The functional integral approach is followed under the mathematical point of view of integration with respect to a stochastic variable. The resulting picture of the laser wave crossing the electron’s trajectory leads to a finite energy gain of the electron in light–matter interaction in vacuum. The analytical theory is compared with three-dimensional PIC simulations from which trajectories of the electron bunches can be extracted. The effective increase in bunch energy is determined under realistic conditions both for the peak (mode) and the cutoff energy of the emitted bunch, in order to make quantitative comparisons with theory and the experimental findings of Cardenas et al , Nature Sci. Reports 9 (2019).

Rock porosity estimation research using refraction seismic waves in Bora Village, Sigi Regency

Rock Porosity Estimation Research Using Refraction Seismic Waves in Bora Village, Sigi Regency has been conducted. The purpose of this study was to determine the distribution of porosity of shallow subsurface rocks at geothermal locations. Data is collected on 6 different trajectories using ES-3000 to get a picture of subsurface waves. The data processing method uses Seisimager software to get a cross-section of the wave velocity and Rockwork software to get a cross-section of the porosity of subsurface rocks. The results showed different rock porosity values for each trajectory. Rock porosity values obtained at track 1 to track 6 are in the range of 27.1% to 30.5%. All trajectories are on a special porosity scale which means they have a large porosity volume as a place to store fluid.

ROGUE WAVE ASYMMETRY IN THE DIRECT NUMERICAL SIMULATIONS OF DIRECTIONAL JONSWAP WAVES

The asymmetry between the troughs from the rear and front sides of rogue waves is the particular object of the present study. In our previous simulations of unidirectional waves the typical picture of a rogue waves possesses the trend that most of the rogue waves where characterized by deeper rear troughs. In the present work we broaden the discussion of the rogue wave front-to-crest asymmetry to the directional case. The direct numerical simulation of primitive water equations is an affordable alternative to the in-situ or laboratory measurements, in particularly when the interest is focused on the long-term evolution or on the detailed consideration of the water wave movement in space and time. In this work we simulate irregular surface waves in the hydrodynamic equations using the High-Order Spectral Method, and focus on the so-called rogue waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/plseXdjpE6c