This study analyzes the scattering of electromagnetic waves in a cold and uniform plasma-filled waveguide driven by an intense relativistic plasma beam under a strong magnetic field. The strong interaction of plasma with electromagnetic waves enables its potential use in different types of waveguides. The Helmholtz equation governs the boundary value problem, which is solved by incorporating the mode matching technique. Invoking the boundary and matching conditions and the derived orthogonality and dispersion relations in this scheme gives an exact solution to the scattering problem. The numerical results shed light on the occurrence of reflection and transmission and flow of power. The power flux is plotted against angular frequency and various duct configurations. The solution is completely validated through the benefit of analytical and numerical results. The investigation of this structure reveals not only its mathematical, but also its physical features.

For the dynamics of three-dimensional electron–positron–ion plasmas, a fluid quantum hydrodynamic model is proposed by considering Landau quantization effects in dense plasma. Ion–neutral collisions in the presence of the Coriolis force are also considered. The application of the reductive perturbation technique produces a wave evolution equation represented by a damped Korteweg–de Vries equation. This equation, however, is insufficient for describing waves in our system at very low dispersion coefficients. As a result, we considered the highest-order perturbation, which resulted in the damped Kawahara equation. The effects of the magnetic field, Landau quantization, the ratio of positron density to electron density, the ratio of positron density to ion density, and the direction cosine on linear dispersion laws as well as soliton and conoidal solutions of the damped Kawahara equation are explored. The understanding from this research can contribute to the broader field of astrophysics and aid in the interpretation of observational data from white dwarfs.

A waveguide-QED with giant atoms, which is capable of accessing various limits of a small one, provides a new paradigm to study photon scatterings. Thus, how to achieve nonreciprocal photon transmissions via such a giant atom setup is highly desirable. In this study, the nonreciprocal single-photon scattering characteristics of a double-driven Λ-type three-level giant atom, where one of the transition couples to a 1D waveguide at two separate points, and the other is driven by two coherent driving fields, are investigated. It is found that a frequency-tunable single-photon diode with an ideal contrast ratio can be achieved by properly manipulating the local coupling phases between the giant atom and the waveguide, the accumulation phase between the two waveguide coupling points, the Rabi frequencies and phase difference of the two driven fields. Compared to the previous single driving schemes, on the one hand, the presence of the second driving field can provide more tunable parameters to manipulate the nonreciprocal single-photon scattering behavior. On the other hand, here perfect nonreciprocal transmission for photons with arbitrary frequencies is achievable by tuning the driving phases while the two driving fields keep on turning, which provides an alternative way to control the nonreciprocal single-photon scattering. Furthermore, the results reveal that both the location and width of each optimal nonreciprocal transmission window is also sensitive to the driving detuning, and a single-photon diode with wide or narrow bandwidth can be realized based on demand. These results may be beneficial for designing nonreciprocal single-photon devices based on a double-driven giant atom setup.

The quantum hydrodynamic model for electrons and ions and the generalized hydrodynamic model for the strongly coupled dust particles are proposed in the strongly coupled quantum dusty plasma, where the combined quantum effects of quantum diffraction, quantum statistic pressure, as well as electron exchange and correlation effects are all considered in the quantum hydrodynamic model. The shear and bulk viscosity effects are included in the viscoelastic relaxation, which leads to the decay of the dust-ion-acoustic waves. The approximate time-dependent solitary solution is obtained by the momentum conservation law in the presence of viscosity.

In this paper, the dust particle surface potential for argon-helium plasma is evaluated analytically and numerically in the context of negatively charged dust particles by employing a power-law $\left({\rm{r}},{\rm{q}}\right)$-distribution function. Recent studies have reported the argon-helium plasma and conducted a brief theoretical and experimental survey. To deepen our understanding further, this study aims to analyze the argon-helium plasma comprehensively using the same pattern but with the $\left({\rm{r}},{\rm{q}}\right)$-distribution function. For this purpose, the current balance equations are derived for electron, helium and argon ions, when these charge species attain the quasineutrality condition. We numerically examined the currents of plasma species for a broad range of effective distribution function parameters ${\rm{r}}$ and ${\rm{q}}.$ It is revealed that the surface potential of dust particles is significantly affected by the parameters ${\rm{r}}$ and ${\rm{q}},$ helium ion-to-electron temperature ratio, argon ion-to-electron temperature ratio, and helium ion to argon ion number density ratio. By incorporating the multi-ion (argon-helium) species, the significance of low-temperature non-Maxwellian dusty (complex) plasma is briefly examined.

In the quantized field formalism, using Kramers–Henneberger unitary transformation as the semi-classical counterpart of Block–Nordsieck transformation, the dynamics of entanglement during the low energy scattering processes in bi-partite systems at the presence of a laser beam fields are studied. The stationary-state Schrodinger equation for the quantum scattering process is obtained for such systems. Then, using partial wave analysis, we introduce a new form of entanglement fidelity considering the effect of high-intensity laser beam fields. The effective potential of hot quantum plasma including plasmon and quantum screening effects is used to obtain the entanglement fidelity ratio as a function of the laser amplitude, and plasmon and Debye length parameters for the elastic electron-ion collisions. It is shown that the plasma free electrons oscillations under interaction with laser beam fields improve the correlations between charged particles and consequently lead to the increase in the system entanglement.

We perform benchmark calculations of the p-wave resonances in the exponentially cosine screened Coulomb potential using the uniform complex-scaling generalized pseudo-spectral method. The present results show significant improvement in calculation accuracy compared to previous predictions and correct the misidentification of resonance electron configuration in previous works. It is found that the resonance states approximately follow an n²-scaling law which is similar to the bound counterparts. The birth of a new resonance would distort the trajectory of an adjacent higher-lying resonance.

In this work, we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring. Accordingly, we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov–Bohm effect and a uniform magnetic field for the considered potential. According to the solution of the equation, we calculated the eigenvalues and eigenfunctions of the considered system. Using the calculated energy spectrum, we obtained the partition function and thermodynamic properties of the system, such as the mean energy, specific heat, entropy and free energy. Our results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum ring. We also study other effects of the rotating term: (1) the effect of different values of rotating parameters, and (2) the effect of negative rotation on the thermodynamic properties of the system. Our results are discussed in detail.

Gaining an understanding of the effects and dynamics of the solar wind is crucial for the study of space weather, Earth's magnetosphere, spacecraft protection, the dynamics of the Solar System, and various other subjects. Observations show that Alfvén waves effectively transfer energy to resonant particles. This study demonstrates how inertial Alfvén waves deliver their energy to resonant plasma particles in different solar environments under certain conditions. The analysis shows that inertial Alfvén waves experience more rapid damping with increasing parallel wavenumber, ambient magnetic field strength, and particle number density, coupled with a decrease in temperature. The rate of energy transfer to resonant particles intensifies with higher temperatures and reduced parallel wavenumber and particle number density. Particles with higher initial velocities actively participate in Landau damping, especially in regions with a stronger ambient magnetic field.

The relativistic binary-encounter-Bethe model with Wannier-type threshold law is employed to obtain the inner-shell ionization cross sections of multi-electron atoms (Ni, Cu, Y, Ag, Au, Yb, Ta, and Pb) for positron impact energies from the thresholds up to 10⁵ keV. There is good agreement between the present calculations and the experimental data. The constant in the acceleration term derived from the Wannier law is determined to be 0.2 and 0.5 for the K- and L-shells, respectively.

In this work, for the first time in the relevant literature, the persistent currents (PC) and induced magnetic fields (IMF) of an endofullerene molecule entrapping a hydrogen atom, under spherical confinement, are investigated. The endofullerene molecule is enclosed within a spherical region and embedded in a plasma environment. The plasma environment is depicted with the more general exponential cosine screened Coulomb potential, and its relevant effects are analyzed by considering plasma screening parameters. The relevant model for endohedral confinement is the Woods–Saxon confinement potential, which is compatible with experimental data. The effects of various forms of C_n are thoroughly elucidated via the analysis of the confinement depth, spherical shell thickness, the inner radius, and the smoothing parameters. To find the bound states in the spherically confined endofullerene, the decoupling of the second-order Dirac equation for the large and small components of the radial atomic wave functions is considered. The Dirac equation with the interaction potential is solved numerically by using the Runge–Kutta–Fehlberg method via the decoupling formalism. The influence of spin orientations on the PC and IMF is also elucidated. The effects of spherical confinement, plasma shielding, and the structural properties of the fullerene on the PC and IMF are thoroughly viewed. Moreover, under given physical conditions, the optimal ranges of these effects are determined.

Motivated by experiments with interacting quantum gases across high partial wave resonance, we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interaction strengths for both p- and d-wave interactions. The equation of state, contact density, momentum distributions and self-energies of single-particle Green’s functions are obtained in the spirit of ladder diagram approximations. The radio-frequency (RF) spectrum, as an important experimental approach for detecting Feshbach molecules or the interaction effect, is calculated at different temperatures. A reversed temperature dependence on the Bose–Einstein condensation side and Bardeen–Cooper–Schrieffer side is identified for both p- and d-wave interactions. An estimate for the signal of RF spectra under typical experimental conditions is also provided.

In a previous paper [Phys. Rev. A 95, 060 701(R) (2017)], we demonstrated that a new type of two-body interaction, which depends on the center of mass (CoM) momentum, can be realized for ultracold atoms via laser-modulated magnetic Feshbach resonance (MFR). Further studies (e.g. L He et al, Phys. Rev. Lett. 120, 045 302 (2018)) show that various interesting phenomena, such as Fulde–Ferrell superfluids, can be induced by scattering between ultracold atoms with this interaction. In this work we investigate the shallow bound states of two ultracold atoms with this type of interaction. We show that when the magnetic field B is below the MFR point B₀, two shallow bound states can appear in this system. Namely, a ‘two-component dimer’ or a dimer with pseudo-spin 1/2 can be formed by two atoms. Furthermore, the dispersion curve of the dimer may have either single or double minimums in the CoM momentum space. The latter case can be explained as a result from significant pseudo-spin-orbital coupling (SOC) effects. Our results show that the ultracold gases with CoM momentum dependent interaction may be a candidate for quantum simulations with ultracold two-component molecules, especially the molecule gases with SOC.

This article presents advancements in an analytical mode-matching technique for studying electromagnetic wave propagation in a parallel-plate metallic rectangular waveguide. This technique involves projecting the solution onto basis functions and solving linear algebraic systems to determine scattering amplitudes. The accuracy of this method is validated via numerical assessments, which involve the reconstruction of matching conditions and conservation laws. The study highlights the impact of geometric and material variations on reflection and transmission phenomena in the waveguide.

In this study, we successfully extracted the ‘knee structure’ for non-sequential double ionization (NSDI) in the helium atom. To achieve this, for the first time, we solved the time-dependent Schrödinger equation in three dimensions for the helium atom, utilizing the shielding charge approximation. Our findings corroborate prior observations by Wang et al [Wang and Eberly, Phys. Rev. Lett. 105, 083001 (2010)], demonstrating that NSDI occurs within a narrower time window in circular polarization compared to linear polarization. As a result, the yield of linear polarization was higher than that of circular polarization, aligning with the previously reported results. Notably, in the case of circular polarization, the time window further narrows with increasing intensity, attributed to a decrease in the time-of-flight.

By numerically solving the time-dependent Schrödinger equation and employing the analytical perturbative model, we investigated the chirp-induced electron vortex in the photoionization of hydrogen atoms by a pair of counter-rotating circularly polarized chirped attosecond extremely ultraviolet pulses. We demonstrated that single-photon ionization of hydrogen atoms generates photoelectron momentum distributions (PMDs) with distinct helical vortex structures either with or without a time delay between two counter-rotating circularly polarized laser pulses. These structures are highly sensitive to both the time delay between the pulses and their chirp parameters. Our analytical model reveals that the splitting of vortex spirals is caused by the sign changing of the chirp-induced frequency-dependent time delay. We showed that to obtain the counterpart of the PMD under a pair of counter-rotating circularly polarized chirped pulses, both chirp parameters and ordering of pulses need to be reversed.

Multiple quantum coherences are often employed to describe quantum many-body dynamics in nuclear spin systems and recently, to characterize quantum phase transitions in trapped ions. Here we investigate the multiple-quantum-coherence dynamics of a spin-1 Bose–Einstein condensate. By adjusting the quadratic Zeeman shift, the condensate exhibits three quantum phases. Our numerical results show that the spectrum of multiple quantum coherence does indeed catch the quantum critical points. More importantly, with only a few low-order multiple quantum coherences, the spin-1 condensate exhibits rich signals of the many-body dynamics, beyond conventional observables. The experimental implementation of such multiple quantum coherence protocol is also discussed.

Motivated by the recent experimental developments in ultracold molecules and atoms, we propose a simple theoretical model to address the disassociation, reflection, and transmission probability of a one-dimensional cold molecule via quantum scattering. First, we show the Born approximation results in the weak interaction regime. Then, by employing the Lippmann-Schwinger equation, we give the numerical solution and investigate the disassociation's dependence on the injection momentum and the interaction strengths. We find that the maximum disassociation rate has a limit when increasing the interaction strengths and injection momentum. We expect that our model can be realized in experiments in the near future.

The influence of a self-focused beam on the stimulated Raman scattering (SRS) process in collisional plasma is explored. Here, collisional nonlinearity arises as a result of non-uniform heating, thereby causing carrier redistribution. The plasma density profile gets modified in a perpendicular direction to the main beam axis. This modified plasma density profile greatly affects the pump wave, electron plasma wave (EPW) and back-scattered wave. The well-known paraxial theory and Wentzel-Kramers-Brillouin approximation are used to derive second-order ordinary differential equations for the beam waists of the pump wave, EPW and the scattered wave. Further to this, the well-known fourth-order Runge-Kutta method is used to carry out numerical simulations of these equations. SRS back-reflectivity is found to increase due to the focusing of several waves involved in the process.

In our previous work [2022 Phys. Chem. Chem. Phys. 24 9685], we used molecular dynamics simulations to show that bulk nanobubbles can be stabilized by forming a compressed amphiphile monolayer at bubble interfaces. This observation closely matches the origin of stability of microemulsions and inspired us to propose here that, in certain cases, stable bulk nanobubbles can be regarded as gaseous analogues of microemulsions: the nanobubble phase and the bubble-containing solution phase coexist with the external gas phase. This three-phase coexistence is then validated by molecular dynamics simulations. The stability mechanism for bulk nanobubbles is thus given: the formation of a compressed amphiphilic monolayer because of microbubble shrinking leads to a vanishing surface tension, and consequently the curvature energy of the monolayer dominates the thermodynamic stability of bulk nanobubbles. With the monolayer model, we further interpret several strange behaviors of bulk nanobubbles: gas supersaturation is not a prerequisite for nanobubble stability because of the vanishing surface tension, and the typical nanobubble size of 100 nm can be explained through the small bending constant of the monolayer. Finally, through analyzing the compressed amphiphile monolayer model we propose that bulk nanobubbles can exist ubiquitously in aqueous solutions.

We investigate the ground-state properties and the dynamics of quasi-one-dimensional quantum droplets of binary Bose condensates by employing the Gaussian state theory. We show that there exists three quantum phases for the ground states of the droplets, including a coherent state and two macroscopic squeezed states. The phase transition between two macroscopic squeezed states is of the third order; while between the macroscopic squeezed state and the coherent is of a crossover type. As for the dynamics, we find that, by tuning the reduced scattering length to a negative value, a significant fraction of the atoms can be transferred from a coherent state to a macroscopic squeezed state. Our studies open up the possibility of generating macroscopic squeezed states using binary condensates.

Strong-field-seeking states are the lowest-energy configurations for paramagnetic molecules in the magnetic field. Molecules in strong-field-seeking states cannot be trapped in a magnetostatic field because a magnetostatic maximum in free space is not allowed. In this paper, we propose an AC magnetic trap composed of two pairs of Helmholtz coils. The spatial magnetic field distribution is numerically calculated and the time-sequential control is depicted. We investigate the influence of the switching frequency and the electric current in the coils on the performance of our trap. Variations of the location and phase-space distribution during a whole switching cycle are simulated. Finally, we study the impact of time during which the field is switched off on the number of captured molecules in a switching cycle.

The present study shows that the Rayleigh-Taylor (RT) instability and its growth rate are strongly dependent on the charge-mass ratio of charged particles in a charged fluid. A higher charge-mass ratio of the charged fluid appears to result in a stronger effect of the magnetic field to suppress the RT instability. We study the RT instabilities for both dusty plasma (small charge-mass ratio of charged particles) and ion-electron plasma (large charge-mass ratio of charged particles). It is found that the impact of the external magnetic field to suppress the RT instability for ion-electron plasma is much greater than that for dusty plasma. It is also shown that, for a dusty plasma, in addition to region parameters such as the external magnetic field, region length, its gradient, as well as dust particle parameters such as number density, mass, and charge of dust particles, the growth rate of the RT instability in a dusty plasma also depends on parameters of both electrons and ions such as the number densities and temperatures of both electrons and ions.

The present work explores the propagation characteristics of high-power beams in weakly relativistic-ponderomotive thermal quantum plasma. A q-Gaussian laser beam is taken in the present investigation. The quasi-optics equation obtained in the present study is solved through a well-established Wentzel–Kramers–Brillouin approximation and paraxial theory approach for obtaining the second-order differential equation describing the behavior of beam width of the laser beam. Further, a numerical simulation of this second-order differential equation is carried out for determining the behavior of the beam width with dimensionless distance for established laser–plasma parameters. The comparison of the present study is made with ordinary quantum plasma and classical relativistic plasma cases.

We propose a method to implement electromagnetically induced grating in a phaseonium medium that has been coherently generated via atomic mechanisms. Phaseonium atoms have a Λ-type structure and three distinct energy levels; such atoms are originally generated in a coherent superposition of two lower levels. The phaseonium system is comprised of three-level atoms with a Λ-type configuration, which are initially prepared in a coherent superposition of two lower levels. To accomplish this spatial modulation based on the susceptibility of phaseonium medium, a standing-wave field is used. By looking at how an optical field diffracts at different relative phases, we find that the zeroth and first order diffraction intensities increase as the relative phase changes. We also investigate the impact of the Rabi frequency of the field on diffraction intensity and notice that an increasing strength of the Rabi frequency leads to amplification in the intensity of both central zeroth order and first-order diffraction. Furthermore, it has been observed that a significant rise in diffraction intensity occurs at longer interaction lengths between external fields and the atomic medium.

By combining all optical, electronic, and mechanical capabilities, electro-optomechanical systems, along with the use of mechanical displacement, the conversion of low-frequency electrical signals into much higher-frequency optical signals is possible. This process provides several capabilities that have very important applications in various fields, including classical, as well as quantum communications. In this regard, the inevitable effect of dissipation on the performance indicators of such systems is one of the important issues affecting its efficiency. One approach for investigating the effect of dissipation is based on a time-dependent Hamiltonian has been known as the Caldirola-Kanai (CK) Hamiltonian, wherein the exponentially increasing mass, i.e. $m\left(t\right)={m}_{0}{{\rm{e}}}^{\gamma t}$ enters the mechanical oscillator system. Utilizing this approach shows that, the performance of the system under the influence of dissipation with CK Hamiltonian formalism, in which the dissipation terms are embedded in the Hamiltonian, are more logical, analytical, and reliable than considering the effect of dissipation with the phenomenological method (including the dissipation effects in the equations of motion by hand), which has been recently used in Bagci et al. (Nature, 507, 81, 2014). In our method, it is also possible to monitor the performance of the system via the adjustment of dissipation components, i.e., resistance $R$ and reactance $L$ (and CK damping parameter $\gamma $) in the electrical (mechanical membrane) part of the system.

Based on the relativistic hydrodynamic model of EM wave–spin plasmas interaction, the spin effects on the relativistic strong EM modes in magnetized plasma are investigated. The dispersion relations of the EM wave propagating parallel and perpendicular to the external magnetic field are obtained. Results show that the strong EM wave modes are affected by the time component of four-spin as well as the increase of electron effective mass. Especially in the case of EM wave propagating parallel to the external magnetic field, the time component of four-spin amplifies the influence of spin effects on the low-frequency modes obviously.

We investigate theoretically the photoionization of triatomic molecular ion ${{\rm{H}}}_{3}^{2+}$ by numerically solving the two-dimensional time-dependent Schrödinger equations under Bohn-Oppenheimer approximation. The results show that the photoelectron momentum distributions (PMDs) of ${{\rm{H}}}_{3}^{2+}$ with different initial states are strongly dependent on the laser ellipticities and molecular orbital symmetry, and the PMDs of degenerate electronic states E^± are mirror images. Also, for degenerate electronic states E^±, vortex structures appear in the PMDs by the counter-rotating circularly polarized laser pulses as the time delay between the two pulses increases, which can be explained by multi-center ionization and ultrafast photoionization model.

We explore the spin–orbit coupling (SOC) mechanism for structured light in coherent atomic media with low-light-level cross-Kerr nonlinearity. Using the five-level M-type electromagnetic induced transparency (EIT) system as a prototype, we show that spin–orbit splitting for a weak spinor image can be generated by a weak trigger field carrying orbital angular momentum (OAM) at low-light intensity. By quantum-optical analogy, the paraxial focusing and defocusing of the two pseudo-spin states in the spinor image can be governed by a Pauli-like equation. More importantly, by changing the EIT parameters, especially the topological charge of the weak trigger field, the SOC-induced radial quantization of the spinor image can be rather significant, giving rise to positive or negative OAM-OAM mode separation in free space. This suggests that the separation can be flexibly controlled due to strong image-vortex interaction based on few-photon cross-Kerr modulation. Our findings may have the potential for all-optical OAM multiplexing and demultiplexing of structured light fields toward few-photon quantum control and multimode communication.

Based on plasma kinetic theory, the instabilities of self-gravitation systems under perturbation with orbital angular momentum (OAM) are investigated, and the concept of twisted Jeans mode is introduced to describe the new phenomenon. The result shows that the growth rate of the Jeans instability is enhanced with the OAM parameter increased, while the critical wave number is consistent with the classical Jeans critical value. It is expected that the present results would give more insight into the evolution and dynamics of a self-gravitational system.

In this paper, an active tunable terahertz bandwidth absorber based on single-layer graphene is proposed, which consists of a graphene layer, a photo crystal plate, and a gold substrate. When the Fermi energy (E_f) of graphene is 1.5 eV, the absorber shows high absorption in the range of 3.7 THz–8 THz, and the total absorption rate is 96.8%. By exploring the absorption mechanism of the absorber, the absorber shows excellent physical regulation. The absorber also shows good adjustability by changing the E_f of graphene. This means that the absorber exhibits excellent tunability by adjusting the physical parameters and E_f of the absorber. Meanwhile, the absorber is polarization independent and insensitive to the incident angle. The fine characteristics of the absorber mean that the absorber has superior application value in many fields such as biotechnology and space exploration.

The transmission properties in Fibonacci quasi-periodic photonic crystals containing negative-zero-positive index metamaterials (NZPIM) are investigated systematically. Because of linear dispersion, an asymmetric band gap appears near the optical Dirac point (DP) only at an oblique incidence. Zero-$\bar{n}$ gaps and Bragg gaps exist when the refractive indexes of NZPIM are negative and positive, respectively. We also obtain gaps induced by total reflection on both sides of the DP gap. The corresponding Goos-Hänchen (GH) shifts and phase variations are also demonstrated in detail. It is shown that the characteristics of the band gaps, GH shifts, and phase variations depend crucially on the incident angle, number of periods, and layer thickness.

We study the spatial structure of a Bose-Einstein condensate (BEC) with a space-dependent s-wave scattering length in a combined trap. There exists a space-dependent nonlinear atomic current in the system. The atomic current has an important influence on the spatial structure of the BEC. Research findings reveal that a large chemical potential can effectively suppress the chaotic spatial structure in the BEC system. Due to the large chemical potential, a strong atomic current is necessary to make the system lose its periodic spatial structure and lead the system into a chaotic spatial structure. But when the atomic current intensity exceeds a critical value, the chaotic spatial structure of the BEC will be completely eliminated and the system will always be kept in a series of single-periodic states as the atomic current becomes stronger. For a very weak atomic current, the spatial structure of the BEC is very sensitive to the intensity of the atomic current and a very small change of the intensity can dramatically change the spatial structure of the BEC. The effects of the combined trap parameters on the spatial structure of BECs are also discussed.

We theoretically investigate the frustrated double ionization (FDI) of molecules with different alignment-dependence using a three-dimensional classical ensemble method. The numerical results show that the FDI probability decreases with increasing wavelength, which is similar to the wavelength dependence of the FDI probability of atoms. Tracing the classical trajectories reveals that the contributions to molecular FDI from single-recollision and multiple-recollision mechanisms are equal in the short wavelength regime. In the long wavelength regime, the single-recollision FDI channel dominates in FDI. The nature in which molecular FDI occurs is identified and explained.

In this work, we investigate the molecular-frame photoelectron momentum and angular distributions (MF-PMD and MF-PAD) of ${{\rm{H}}}_{2}^{+}$ in the presence of XUV Attosecond Pulses. We present the alignment-sensitive effect of MF-PMDs and MF-PADs when the laser field polarization and the molecular axis are close to parallel geometry. Our results show that the MF-PADs and MF-PMDs of single-photon ionization of ${{\rm{H}}}_{2}^{+}$ ion vary drastically when the alignment slightly shifts from parallel geometry to a small alignment angle (e.g. 4°) between the laser polarization direction and the molecular axis at the equilibrium inter-nuclear distance of R_c = 2 atomic units. As R_c increases to 4 atomic units, such sensitivity is decreased. The R_c-dependent transition cross-sections in different channels are found to be the origin of such sensitivity.

A patterned monolayer graphene metamaterial structure consisting of six graphene blocks and two graphene strips is proposed to generate triple plasmon-induced transparency (PIT). Triple-PIT can be effectively modulated by Fermi levels of graphene. The theoretically calculated results by coupled mode theory show a high matching degree with the numerically simulated results by finite-difference time-domain. Intriguingly, the high-sensitive refractive index sensing and excellent slow-light performance can be realized in the proposed graphene metamaterial structure. The sensitivity (S) and figure of merit can reach up to 5.7115 THz RIU⁻¹ and 116.32, respectively. Moreover, the maximum group refractive index is 1036. Hence, these results may provide a new idea for designing graphene-based sensors and slow light devices.

Doppler cooling of ⁸⁸Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser fields. Using a semi-classical approach, we show that the relevant physical quantities in the cooling process, such as optical forces, the damping coefficient, Doppler temperature, and atom number in the trap, are strongly affected by the laser amplitude and phase fluctuations. We find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating lasers. This implies an additional heating mechanism exists due to the laser fluctuations. Furthermore, our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.

Attosecond transient absorption (ATA) has been developed as an all-optical technique for probing electron dynamics in matter. Here we present a scheme that can modify the laser-induced state and the corresponding ATA spectrum via excitation by a pair of XUV attosecond pulses and by a time-delayed mid-infrared (MIR) laser probe. Different from the scheme of the electronic excitation by a single XUV attosecond pulse, the application of a pair of XUV pulses provides extra degrees of freedom, such as the time delay and the intensity ratio between two XUV pulses, which make it possible to adjust the pump process, resulting in the modification of the ATA spectrum. We show that by varying the time delay between the two XUV pulses, the population of the dark state and the ATA spectrum of the laser-induced state have periodic modulations. We also demonstrate that the peak of the ATA spectrum of the laser-induced state appears at a fixed time delay between the XUV pair and the MIR laser when the intensity ratio is large, and it changes with the time delay when the intensity ratio is small, which can be related to either one of two peaks in the population of the dark state.