Resonant Interaction Research Articles

Light squeezing enhancement by coupling nonlinear optical cavities

In this paper, we explore the squeezing effect generated by two coupled optical cavities. Each cavity contains a second-order nonlinear material and coherently pumped by a laser. Our results show that light intensity is strongly improved due to the presence of the nonlinearities and mainly depends on the detunings between external laser frequencies and cavity modes. More interestingly, the proposed scheme could enhance light squeezing for moderate coupling between cavities : the squeezing generated by one cavity is enhanced by the other one. For resonant interaction, highest squeezing effect is obtained near resonance. When fields are non resonant, squeezing increases near resonance of the considered cavity, but decreases for large detunings relative to the second cavity. Further, when the dissipation rate of the second cavity is smaller than the first, the squeezing could be improved, attaining nearly the perfect squeezing. While the temperature elevation has a negative impact overall on the nonclassical light, squeezing shows an appreciable resistance against thermal baths for appropriate parameter sets.

Resonant Interactions Between Relativistic Electrons and EMIC Waves Modified by Partial Shell Proton Velocity Distributions

AbstractResonant interactions of relativistic electrons with electromagnetic ion cyclotron (EMIC) waves were previously considered under the cold plasma approximation or in hot plasmas with bi‐Maxwellian distributions. Here, we examine their resonant interactions in hot plasmas with partial shell distributions and find that such distributions can significantly alter the dispersion relation of EMIC waves and thus the corresponding wave‐induced electron pitch angle scattering rates and loss timescales compared to those under the cold plasma assumption. Regardless of wave band and frequency, partial shell distributed hot protons tend to uplift the electron minimum resonant energy, and reduce (raise) the pitch angle scattering rates of electrons at low (high) energies and large (small) pitch angles. Correspondingly, the loss timescales lengthen for low‐energy electrons but shorten for high‐energy electrons. Such tendencies are generally more significant for lower‐frequency EMIC waves and larger shell temperature, anisotropic degree, and concentration.

A Hamiltonian theory for nonlinear resonant wave–particle interaction in weakly inhomogeneous magnetic field

We develop a Hamiltonian theory for the nonlinear resonant interactions between energetic particles and nonlinear frequency chirping waves in the weakly inhomogeneous magnetic field. A canonical transformation is constructed to separate the fast and slowly varying scales, and the Hamiltonian of the resonant particle is transformed to the local resonance reference frames. The Vlasov equation of the local distribution function moving at the local resonance velocity is obtained using Liouville's theorem. The evolution for the slowly varying wave envelope is derived from the Ampère's law with both cold plasma and energetic particle currents. The Vlasov equation coupled with the wave envelope equation self-consistently describes the dynamics of the deeply trapped resonant particles and the slowly varying coherent wave envelope. The application of the theory to the frequency chirping chorus wave in magnetospheric plasmas is also discussed.

Suprathermal Electron Transport in the Solar Wind: Effects of Coulomb Collisions and Whistler Turbulence

The nature and radial evolution of solar wind electrons in the suprathermal energy range are studied. A wave–particle interaction tensor and a Fokker–Planck Coulomb collision operator are introduced into the kinetic transport equation describing electron collisions and resonant interactions with whistler waves. The diffusion tensor includes diagonal and off-diagonal terms, and the Coulomb collision operator applies to arbitrary electron velocities describing collisions with both background protons and electrons. The background proton and electron densities and temperatures are based on previous turbulence models that mediate the supersonic solar wind. The electron velocity distribution functions and electron heat flux are calculated. Comparison and analysis of the numerical results with analytical solutions and observations in the near-Sun region are made. The numerical results reproduce well the creation of the sunward electron deficit observed in the near-Sun region. The deficit of the electron velocity distribution function below the core Maxwellian fit at low velocities results from Coulomb collisions, and the excess part above the core Maxwellian fit at high velocities is determined by strong wave–particle interactions.

Electron Resonant Interaction With Coherent ULF Waves: Hamiltonian Approach

AbstractElectron resonant interaction with ultra‐low‐frequency (ULF) waves is considered to be a driver of electron radial transport in Earth’s inner magnetosphere. Traditional concept of such interaction assumes the electron slow diffusive scattering by a broad‐band ULF spectrum, but recent spacecraft observations reported a possibility for electrons to resonate nonlinearly with intense coherent ULF waves. This study proposes a theoretical model describing the main elements of such nonlinear resonant interactions. We implement a Hamiltonian approach to describe equatorial electron motion in a dipole magnetic field and electric ULF wavefield and demonstrate the ULF‐electron interactions has two basic nonlinear resonant regimes: phase bunching and phase trapping. Finally, we discuss possible applications of the proposed theoretical approach and the importance of ULF‐electron nonlinear resonances.

Thelxinoë: Recognizing Human Emotions Using Pupillometry and Machine Learning

In this study, we present a method for emotion recognition in Virtual Reality (VR) using pupillometry. We analyze pupil diameter responses to both visual and auditory stimuli via a VR headset and focus on extracting key features in the time-domain, frequency-domain, and time-frequency domain from VR-generated data. Our approach utilizes feature selection to identify the most impactful features using Maximum Relevance Minimum Redundancy (mRMR). By applying a Gradient Boosting model, an ensemble learning technique using stacked decision trees, we achieve an accuracy of 98.8% with feature engineering, compared to 84.9% without it. This research contributes significantly to the Thelxinoë framework, aiming to enhance VR experiences by integrating multiple sensor data for realistic and emotionally resonant touch interactions. Our findings open new avenues for developing more immersive and interactive VR environments, paving the way for future advancements in virtual touch technology.

Development of methods and means to improve environmental, radiation and industrial safety of NPPs with WWER-1200

The introduction provides an overview of scientific research on the sources of generation, characteristics and classification of infrasound. It is noted that infrasound has a number of features related to the low oscillation frequency of the elastic medium and the diffraction property. Infrasound has harmful effects on hearing, breathing, vision, gastrointestinal tract, nervous and cardiovascular systems, brain and vestibular apparatus, leading to decreased performance, general malaise and premature aging of the human body. The methodology of theoretical substantiation of methods for detecting previously unknown sources of infrasound, improving the environmental, radiation and industrial safety of nuclear power plants with WWER-1200 is based on the use of digital acoustic models of primary circuit equipment responsible for operational safety developed under the guidance of K.N. Proskuryakov. The methodology of practical confirmation of the results of computational and theoretical forecasting of acoustic parameters of previously unknown infrasound sources is presented in the form of two stages: a) development of a methodology for verifying forecasting results and selection of power units No. 1, 2 of Novovoronezh NPP-2 in the form of objects; b) investigation of the conditions for the occurrence of vibro-infrasound resonances in the first circuit. The developed method for investigating infrasound sources has been verified at the WWER-1200 reactor plant. When discussing the results of the conducted research, previously unknown sources of infrasound were identified. Innovative methods of analysis and damping of infrasound sources have been developed and a patent for invention No. 2803181 «A method for preventing resonant interaction of vibrations of water-water power reactor equipment with acoustically standing waves and a device for its implementation» has been obtained. The errors of the chief designer of reactor installations with WWER in the regulations for the launch of new power units are noted; their negative consequences for the health of personnel and the condition of equipment responsible for environmental, radiation and industrial safety of nuclear power plants with WWER are indicated

High-speed impulsive stimulated Brillouin microscopy

Brillouin microscopy, which maps the elastic modulus from the frequency shift of scattered light, has evolved to a faster speed for the investigation of rapid biomechanical changes. Impulsive stimulated Brillouin scattering (ISBS) spectroscopy has the potential to speed up measurement through the resonant amplification interaction from pulsed excitation and time-domain continuous detection. However, significant progress has not been achieved due to the limitation in signal-to-noise ratio (SNR) and the corresponding need for excessive averaging to maintain high spectral precision. Moreover, the limited spatial resolution also hinders its application in mechanical imaging. Here, by scrutinizing the SNR model, we design a high-speed ISBS microscope through multi-parameter optimization including phase, reference power, and acquisition time. Leveraging this, with the further assistance of the Matrix Pencil method for data processing, three-dimensional mechanical images are mapped under multiple contrast mechanisms for a millimeter-scale polydimethylsiloxane pattern immersed in methanol, enabling the identification of these two transparent materials without any contact or labeling. Our experimental results demonstrate the capability to maintain high spectral precision and resolution at a sub-millisecond integration time for one pixel. With a two-order improvement in the speed and a tenfold improvement in the spatial resolution over the state-of-the-art systems, this method makes it possible for ISBS microscopes to sensitively investigate rapid mechanical changes in time and space.

A (2+1) -dimensional evolution model of Rossby waves and its resonance Y-type soliton and interaction solutions

In this paper, we derive a Kadomtsev-Petviashvili equation by using the multi-scale expansion and perturbation method, which is a model from the potential vorticity equation in the traditional approximation and describes the Rossby wave propagation properties. The N-soliton solutions, resonance Y-type soliton solutions, resonance X-type soliton solutions and interaction solutions of the equation are obtained with the help of dependent-variable transformation. In addition, the composite graphs are given to view the resonance phenomenon of Rossby waves. The results better enrich the research of Rossby waves in ocean dynamics and atmospheric dynamics.

The challenge to understand the zoo of particle transport regimes during resonant wave-particle interactions for given survey-mode wave spectra

Quasilinear theories have been shown to well describe a range of transport phenomena in magnetospheric, space, astrophysical and laboratory plasma “weak turbulence” scenarios. It is well known that the resonant diffusion quasilinear theory for the case of a uniform background field may formally describe particle dynamics when the electromagnetic wave amplitude and growth rates are sufficiently “small”, and the bandwidth is sufficiently “large”. However, it is important to note that for a given wave spectrum that would be expected to give rise to quasilinear transport, the quasilinear theory may indeed apply for given range of resonant pitch-angles and energies, but may not apply for some smaller, or larger, values of resonant pitch-angle and energy. That is to say that the applicability of the quasilinear theory can be pitch-angle dependent, even in the case of a uniform background magnetic field. If indeed the quasilinear theory does apply, the motion of particles with different pitch-angles are still characterised by different timescales. Using a high-performance test-particle code, we present a detailed analysis of the applicability of quasilinear theory to a range of different wave spectra that would otherwise “appear quasilinear” if presented by e.g., satellite survey-mode data. We present these analyses as a function of wave amplitude, wave coherence and resonant particle velocities (energies and pitch-angles), and contextualise the results using theory of resonant overlap and small amplitude criteria. In doing so, we identify and classify five different transport regimes that are a function of particle pitch-angle. The results in our paper demonstrate that there can be a significant variety of particle responses (as a function of pitch-angle) for very similar looking survey-mode electromagnetic wave products, even if they appear to satisfy all appropriate quasilinear criteria. In recent years there have been a sequence of very interesting and important results in this domain, and we argue in favour of continuing efforts on: (i) the development of new transport theories to understand the importance of these, and other, diverse electron responses; (ii) which are informed by statistical analyses of the relationship between burst- and survey-mode spacecraft data.

Minimal Quantization Model in Pilot-Wave Hydrodynamics.

Investigating how classical systems may manifest dynamics analogous to those of quantum systems is a broad subject of fundamental interest. Walking droplets, which self-propel through a resonant interaction with their own wave field, provide a unique macroscopic realization of wave-particle duality that exhibits behaviors previously thought exclusive to quantum particles. Despite significant efforts, elucidating the precise origin and form of the wave-mediated forces responsible for the walker's quantumlike behavior remained elusive. Here, we demonstrate that, owing to wave interference, the force responsible for orbital quantization originates from waves excited near stationary points on the walker's past trajectory. Moreover, we derive a minimal model with the essential ingredients to capture quantized orbital dynamics, including quasiperiodic and chaotic orbits. Notably, this minimal model provides an explicit distinction between local forces, which account for the walker's preferred speed and wave-induced added mass, and spatiotemporal nonlocal forces responsible for quantization. The quantization mechanism revealed here is generic, and will thus play a role in other hydrodynamic quantum analogs.

Near-Unity Light-Matter Interaction in Mid-Infrared van der Waals Metasurfaces.

Accessing mid-infrared radiation is of great importance for a range of applications, including thermal imaging, sensing, and radiative cooling. Here, we study light interaction with hexagonal boron nitride (hBN) nanocavities and reveal strong and tunable resonances across its hyperbolic transition. In addition to conventional phonon-polariton excitations, we demonstrate that the high refractive index of hexagonal boron nitride outside the Reststrahlen band allows enhanced light-matter interactions in deep subwavelength (<λ/15) nanostructures across a broad 7-8 μm range. Emergence and interplay of Fabry-Perot and Mie-like resonances are examined experimentally and theoretically. Near-unity absorption and high quality (Q ≥ 80) resonance interaction in the vicinity of the hBN transverse optical phonon is further observed. Our study provides avenues to design highly efficient and ultracompact structures for controlling mid-infrared radiation and accessing strong light-matter interactions with hBN.

Universal and Ultrafast Quantum Computation Based on Free-Electron-Polariton Blockade

Cavity QED, wherein a quantum emitter is coupled to electromagnetic cavity modes, is a powerful platform for implementing quantum sensors, memories, and networks. However, due to the fundamental trade-off between gate fidelity and execution time, as well as limited scalability, the use of cavity QED for quantum computation was overtaken by other architectures. Here, we introduce a new element into cavity QED—a free charged particle, acting as a flying qubit. Using free electrons as a specific example, we demonstrate that our approach enables ultrafast, deterministic, and universal discrete-variable quantum computation in a cavity-QED-based architecture, with potentially improved scalability. Our proposal hinges on a novel excitation blockade mechanism in a resonant interaction between a free-electron and a cavity polariton. This nonlinear interaction is faster by several orders of magnitude with respect to current photon-based cavity-QED gates, enjoys wide tunability and can demonstrate fidelities close to unity. Furthermore, our scheme is ubiquitous to any cavity nonlinearity, either due to light-matter coupling as in the Jaynes-Cummings model or due to photon-photon interactions as in a Kerr-type many-body system. In addition to promising advancements in cavity-QED quantum computation, our approach paves the way towards ultrafast and deterministic generation of highly entangled photonic graph states and is applicable to other quantum technologies involving cavity QED. Published by the American Physical Society 2024

Eccentric black hole mergers via three-body interactions in young, globular, and nuclear star clusters

Eccentric mergers are a signature of the dynamical formation channel of binary black holes (BBHs) in dense stellar environments and hierarchical triple systems. Here, we investigate the formation of eccentric mergers via binary-single interactions by means of 2.5 × 105 direct N-body simulations. Our simulations include post-Newtonian terms up to the 2.5th order and model the typical environment of young (YSCs), globular (GCs), and nuclear star clusters (NSCs). Around 0.6% (1%) of our mergers in NSCs (GCs) have an eccentricity &gt; 0.1 when the emitted gravitational wave frequency is 10 Hz in the source frame, while in YSCs this fraction rises to 1.6%. Approximately ∼63% of these mergers are produced by chaotic, resonant interactions where temporary binaries are continuously formed and destroyed, while ∼31% arise from an almost direct collision of two black holes (BHs). Lastly, ∼6% of these eccentric mergers occur in temporary hierarchical triples. We find that binaries undergoing a flyby generally develop smaller tilt angles with respect to exchanges. This result challenges the idea that perfectly isotropic spin orientations are produced by dynamics. The environment dramatically affects BH retention: 0%, 3.1%, and 19.9% of all the remnant BHs remain in YSCs, GCs, and NSCs, respectively. The fraction of massive BHs also depends on the host cluster properties, with pair-instability (60 ≤ MBH/M⊙ ≤ 100) and intermediate-mass (MBH ≥ 100 M⊙) BHs accounting for approximately ∼44% and 1.6% of the mergers in YSCs, ∼33% and 0.7% in GCs, and ∼28% and 0.4% in NSCs, respectively.

Key Factors Determining Nightside Energetic Electron Losses Driven by Whistler‐Mode Waves

AbstractEnergetic electron losses by pitch‐angle scattering and precipitation to the atmosphere from the radiation belts are controlled, to a great extent, by resonant wave particle interactions with whistler‐mode waves. The efficacy of such precipitation is primarily modulated by wave intensity, although its relative importance, compared to other wave and plasma parameters, remains unclear. Precipitation spectra from the low‐altitude, polar‐orbiting ELFIN mission have previously been demonstrated to be consistent with energetic precipitation modeling derived from empirical models of field‐aligned wave power across a wide swath of local‐time sectors. However, such modeling could not explain the intense, relativistic electron precipitation observed on the nightside. Therefore, this study aims to additionally consider the contributions of three modifications—wave obliquity, frequency spectrum, and local plasma density—to explain this discrepancy on the nightside. By incorporating these effects into both test particle simulations and quasi‐linear diffusion modeling, we find that realistic implementations of each individual modification result in only slight changes to the electron precipitation spectrum. However, these modifications, when combined, enable more accurate modeling of ELFIN‐observed spectra. In particular, a significant reduction in plasma density enables lower frequency waves, oblique, or even quasi field‐aligned waves to resonate with near ∼1 MeV electrons closer to the equator. We demonstrate that the levels of modification required to accurately reproduce the nightside spectra of whistler‐mode wave‐driven relativistic electron precipitation match empirical expectations and should therefore be included in future radiation belt modeling.

Quasi-Periodic Traveling Waves on an Infinitely Deep Perfect Fluid Under Gravity

We consider the gravity water waves system with a periodic one-dimensional interface in infinite depth and we establish the existence and the linear stability of small amplitude, quasi-periodic in time, traveling waves. This provides the first existence result of quasi-periodic water waves solutions bifurcating from a completely resonant elliptic fixed point. The proof is based on a Nash–Moser scheme, Birkhoff normal form methods and pseudo differential calculus techniques. We deal with the combined problems of small divisors and the fully-nonlinear nature of the equations. The lack of parameters, like the capillarity or the depth of the ocean, demands a refined nonlinear bifurcation analysis involving several nontrivial resonant wave interactions, as the well-known “Benjamin-Feir resonances”. We develop a novel normal form approach to deal with that. Moreover, by making full use of the Hamiltonian structure, we are able to provide the existence of a wide class of solutions which are free from restrictions of parity in the time and space variables.

Fast generation of spin squeezing via resonant spin-boson coupling

We propose protocols for the creation of useful entangled states in a system of spins collectively coupled to a bosonic mode, directly applicable to trapped-ion and cavity QED setups. The protocols use coherent manipulations of the resonant spin-boson interactions naturally arising in these systems to prepare spin squeezed states exponentially fast in time. The resonance condition harnesses the full spin-boson coupling and thus avoids the slower timescales when operating in the off-resonance regime. We demonstrate the robustness of the protocols by analyzing the effects of natural sources of decoherence in these systems and show their advantage compared to more standard slower approaches where entanglement is generated with off-resonant spin-boson interactions.

Realization of an Extremely Anisotropic Heisenberg Magnet in Rydberg Atom Arrays

Strong mutual interaction which correlates elementary excitations of quantum matter plays a key role in a range of emergent phenomena, from binding and condensation to quantum thermalization and many-body localization. Here, we employ a Rydberg quantum simulator to experimentally demonstrate strongly correlated spin transport in anisotropic Heisenberg magnets, where the magnon-magnon interaction can be tuned 2 orders of magnitude larger than the magnon hopping strength. In our approach, the motion of magnons is controlled by an induced spin-exchange interaction through far off-resonant driving, which enables coherent transport of a single Rydberg excitation across a chain of ground-state atoms. As the most prominent signature of a giant anisotropy, we show that nearby Rydberg excitations form distinct types of magnon-bound states, where a tightly bound pair exhibits frozen dynamics in a fragmented Hilbert space, while a loosely bound pair propagates and establishes correlations beyond a single lattice site. Our scheme complements studies using resonant dipole-dipole interactions between Rydberg states and opens the door to exploring quantum thermodynamics with ultrastrong interactions and kinetic constraints. Published by the American Physical Society 2024

A survey of westward‐propagating mixed Rossby–Gravity waves and quantification of their association with extratropical disturbances

AbstractIn this study we have conducted a survey of westward‐propagating mixed Rossby–Gravity (MRG) wave events in the upper troposphere and quantified their association with the intrusions of extratropical disturbances for the period 1979–2019. MRG wave events are identified by imposing the meridional structure of theoretical MRG waves onto the equatorial meridional winds at 200 hPa. In all, 2390 MRG wave events are identified and the majority (61%) of them occurred during the months of May–October, and 65% of the total MRG wave events occurred over the central–east Pacific and Atlantic Ocean domains. Not only the frequency of occurrence but also the amplitude, wavenumber and trapping scale of the MRG wave events are found to exhibit a clear seasonality. MRG wave events associated with intrusions of extratropical disturbances are identified as when the potential vorticity on the 350‐K isentropic surface at 15° latitude exceeded 1 Potential Vorticity Unit (PVU) in the vicinity of the MRG wave events. We find that 37% of the MRG wave events are intrusion MRG wave events and a large majority (88%) of such events occurred over the central–east Pacific and Atlantic Ocean domains. It is also noteworthy that nearly 70% of such intrusions occurred in the winter hemisphere where the westerly wind ducts are well developed. Over the central–east Pacific during northern hemispheric (NH) winter, it is observed that the intrusion MRG wave events have a bigger amplitude and have a larger meridional extent compared to non‐intrusion MRG wave events. They also exhibit a similar spatial scale as the extratropical disturbances implying that resonant interactions may be a primary mechanism for the genesis of MRG wave events. During NH summer, on the other hand, MRG wave events are primarily triggered by convective processes and the extratropical disturbances may be instrumental in amplifying their amplitude.

Possible Global Generation Region of Nonlinear Whistler‐Mode Chorus Emission Waves at Mercury

AbstractChorus waves are a kind of intense electromagnetic emission wave in magnetized planets and can play important roles in the kinetic electron dynamics in planetary magnetospheres. Rapid changes of the ring electron current belt in Mercury’s magnetosphere and the contribution of chorus waves have remained long‐standing scientific issues from the first Mercury flyby observations by Mariner 10 in 1970s because of the small size of the magnetosphere. Based on theoretical analyses and simulations successfully reconstructing Earth’s chorus wave properties, we report on possible generation regions of chorus waves in Mercury’s magnetosphere. The theoretical analysis for low‐temperature‐anisotropy electrons shows a clear asymmetric day–night spatial distribution of the possible chorus generation region because of the difference in the nonlinear convective wave growth along the magnetic field lines. Simulation results show a rapid enhancement of the ring electron current belt by resonant interactions with repetitive chorus waves. Our study suggests that energetic electrons in Mercury’s magnetosphere can be enhanced locally by nonlinear chorus wave–particle interactions.