Dipolar Bose-Hubbard model in finite-size real-space cylindrical lattices

Based on the exact solution method, the ground state and quench dynamics properties of one-dimensional single-spin flipped Fermi gas with repulsion interaction are studied. With the Bethe wave function, the single-body correlation function and two-body correlation function of the ground state and those between different eigen-states can be reduced into a summation of simple functions, thereby greatly reducing the computational difficulty. For the system in the ground state, the single-body correlation functions and two-body correlation functions as well as momentum distributions for spin-up particles are investigated in real space with different interaction strengths. As the interaction strength increases, the number of nodes in the single-body correlation function remains unchanged, while the amplitude of oscillation decreases. Meanwhile, the number of peaks in the two-body correlation function increases by one due to interaction, indicating that the spin-down particle behaves as a spin-up particle. The momentum distribution becomes more smooth around Fermi surface with the interaction strength increasing. The interaction quench dynamics is investigated. The system is prepared in the ground state of ideal Fermi gas, and then the interaction strength is quenched to a finite positive value. The system evolves under time-dependent Schrödinger equation. The overlap between the initial state and eigen-state of post-quench interaction strength is expressed in the form of continued multiplication. The square of the modulus of this overlap, which represents the occupation probability, is calculated. We find that the occupation probabilities of the ground state and doubly degenerated excited state always have the first and the second largest value for an arbitrary interaction strength, respectively, which means that the difference in eigenenergy between these two states gives the primary period of oscillation. For relatively large particle number (<inline-formula><tex-math id="M2">\begin{document}$ N\geqslant10$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20231425_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20231425_M2.png"/></alternatives></inline-formula>), the primary period always does not change under different interaction strengths.It is found that in the case of interaction quenching, the momentum distribution and the correlation function show periodic oscillations. When the interaction strength is adjusted to a relatively small value, the oscillation periodicity is well-defined and the oscillation amplitude is small. The system can be approximated by a two-level model. When the interaction strength increases to a very large value, the oscillation periodicity worsens and the amplitude increases, but a primary period remains unchanged. Although the overall deviation is far from the initial state, it is very close to the initial state at time <inline-formula><tex-math id="M3">\begin{document}$ t=mL^2/(2\pi\hbar)$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20231425_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20231425_M3.png"/></alternatives></inline-formula>. This is because the difference between most energy eigenvalues is almost an integral multiple of energy unit <inline-formula><tex-math id="M4">\begin{document}$ 2\times\left(2\pi/L\right)^{2}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20231425_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20231425_M4.png"/></alternatives></inline-formula>.

Nonperturbative coupling between cavity photons and excitons leads to the formation of hybrid light-matter excitations, termed polaritons. In structures where photon absorption leads to the creation of excitons with aligned permanent dipoles, the elementary excitations, termed dipolar polaritons, are expected to exhibit enhanced interactions. Here, we report a substantial increase in interaction strength between dipolar polaritons as the size of the dipole is increased by tuning the applied gate voltage. To this end, we use coupled quantum well structures embedded inside a microcavity where coherent electron tunneling between the wells creates the excitonic dipole. Modifications of the interaction strength are characterized by measuring the changes in the reflected light intensity when polaritons are driven with a resonant laser. The factor of 6.5 increase in the interaction-strength-to-linewidth ratio that we obtain indicates that dipolar polaritons could constitute an important step towards a demonstration of the polariton blockade effect, and thereby to form the building blocks of many-body states of light.

If related species share enemies, variation in the damage experienced by species within a community may be predictable based on phylogeny. We examined the hypothesis that plant species more closely related to other community members experience greater herbivory by assessing leaf damage to native and exotic plants in two North American communities: an Eastern hardwood forest and a Rocky Mountain montane community. Pairwise phylogenetic distances between focal species and the hundreds of other native species in each community were calculated. We examined the influence of four measures of relatedness within each community: NND (phylogenetic distance to the nearest native neighbor), MPD (mean phylogenetic distance to the native species in the community), and two new metrics, MIPD (mean inverse phylogenetic distance) and INND (inverse nearest neighbor distance). These new metrics assume a nonlinear increase in interaction strength with relatedness; in the context of natural enemies, they posit that the sharing of enemies between any two species increases nonlinearly with their relatedness. Using regression models, we found that herbivore damage decreased with decreasing phylogenetic similarity of focal species to native species (as measured by MIPD) in both sites, although the pattern was significant only for native focal species in the montane community and exotic focal species in the hardwood forest. Similar decreases in herbivory with decreasing relatedness were detected using INND (montane natives) and MPD (hardwood forest exotics). There was no significant relationship between NND and herbivory for any of the four site by focal plant origin combinations. Our results are the first to support the hypothesis that native species can escape attack as a function of their phylogenetic dissimilarity to the larger community of native species, and to demonstrate that exotic species show these patterns in the wild (as opposed to in common gardens). We suggest that phylogenetic distance metrics assuming a nonlinear increase in interaction strength with relatedness show promise for broader application.

Scattering characteristics of anisotropic cylindrical phase-gradient metasurfaces (MSs) with various helical Pancharatnam-Berry phase (PB-phase) coding are studied. The efficiencies of the scattering field reduction of circularly polarized (CP) waves in the forward half-space is compared for three different MS models with the same PB-phase gradient in the azimuthal direction and different phase gradients in the axial direction. The metasurfaces are conformally located on semi-cylindrical metallic polyhedral prisms. The meta-particles are of the form of triple coupled split-ring resonators. Spiral coding of the PB-phase of MS unit cells in the azimuthal and axial directions is carried out by the rotation of the meta-particles. The effect of constant phase gradients on the frequency characteristics of backscattered fields and bistatic diagrams of scattering of CP-waves in the azimuthal and meridional planes is numerically estimated. It is shown that the axial phase gradient causes more efficient anomalous scattering of co- and cross-polarized CP-waves. It leads to the deviation of intense diffraction lobes from the normal in the meridional plane by a large angle, with a shift of the lobes in the azimuthal plane. Bigradient MSs provide the scattering field reduction of CP-waves by at least 10 dB in the band from 10-12 GHz to 18.5 GHz in almost the entire forward half-space in the azimuthal plane and in the sector of angles up to ±45° in the meridional plane.

Evolution of disturbances in three-dimensional boundary layers

Hematopoietic stem cells (HSC) reside within specialized microenvironments that undergo dynamic changes throughout development and aging to support HSC function. However, the evolving cell-cell communication networks within these niches remain largely unexplored. This study integrates single-cell RNA sequencing datasets to systematically characterize the HSC niche interactome from ontogeny to aging. We reconstructed single-cell atlases of HSC niches at different developmental stages, revealing stage-specific cellular compositions and interactions targeting HSC. During HSC maturation, our analysis identified distinct patterns of ligand-receptor interactions and signaling pathways that govern HSC emergence, expansion, and maintenance. HSC aging was accompanied by a decrease in supportive niche interactions, followed by an adaptive increase in interaction strength in old adult bone marrow. This complex aging process involved the emergence of interactions associated with inflammation, altered stem cell function, and a decline in the efficacy of key signaling pathways. Our findings provide a comprehensive understanding of the dynamic remodeling of the HSC niche interactome throughout life, paving the way for targeted interventions to maintain HSC function and promote healthy aging. This study offers valuable insights into the intricate cell-cell communication networks that govern HSC behavior and fate, with implications for hematological disorders and regenerative medicine.

The role of interaction energy in driving planar liquid crystalline systems towards the formation of nematic phases is analyzed for a series of Gay-Berne mesogen which differs in their inter-particle interaction strengths. In an attempt to gain a deeper insight into how the Gay-Berne potential controls the inter-particle interaction and in consequence the system properties, we choose its exponents [υ, µ] as our control parameter. Isochoric-Isothermal (NVT) Monte Carlo Simulation is performed in 2 dimensions on the above systems to study their structural correlations. The correlations present in the system is studied both as a function of temperature and inter-particle interaction strength. Our results depict that the nematic ordering bears a direct relation with the increase in interaction strength while varying inversely with an increase in temperature.

Three analogues of the SIFSIX-3-M family, namely SIFSIX-3-Zn, SIFSIX-3-Ni, and SIFSIX-3-Cu were investigated using theoretical methods to determine the effect of pore-size and pore-chemistry on the adsorption of CO2 in Hybrid Ultramicroporous Materials (HUMs). Classical Grand Canonical Monte Carlo (GCMC), Molecular Dynamics (MD), and Density Functional Theory (DFT) were used to explore the sorption properties of these HUMs, which show high affinity toward CO2. Simulated adsorption isotherms are in good agreement with experimental results. Also, calculated isosteric enthalpies of adsorption (Qst) follow the trend: SIFSIX-3-Cu > SIFSIX-3-Ni > SIFSIX-3-Zn, which agrees with experimental measurements. The interaction energy between a CO2 molecule and the HUM pore was determined by DFT-D2 level of theory calculations. As might be expected, the strongest interaction energy (56.89 kJ mol-1) was observed in the HUM with smallest pore size (SIFSIX-3-Cu) compared to SIFSIX-3-Ni (52.21 kJ mol-1) and SIFSIX-3-Zn (48.46 kJ mol-1) each with increasing pore dimensions, respectively. This increase in interaction strength is attributed to the shorter distance between the electronegative equatorial fluorine atoms of the SiF62- pillar and electropositive carbon atom of carbon dioxide. Finally, uncertainty about the exact crystallographic position of equatorial fluorine atoms was clarified with DFT-D2 calculations. It was observed that simulated interaction energies are in best agreement with experimental Qst values when equatorial fluorine atoms are at a 45° angle with respect to a-axis. Our observations will be valuable in aiding the rational design of improved variants of SIFSIX-3-M and related materials for the selective adsorption of CO2.

Motivated by the significant effect of particle–particle interactions on the driven stochastic transport system, we examine how interacting particles control the lattice polymerization and depolymerization dynamics under the restricted supply of involved resources. We carried out a theoretical analysis based on the simple mean-field and cluster mean-field theory to predict the fundamental role of interactions on the steady-state length dynamics. It has been detected that there is a strong correlation between the lattice length dynamics and the concentration of the total number of lattice sites in the reservoir. For lower and higher values of available resources, depolymerization and polymerization process dominates the lattice dynamics, respectively, while for intermediate values of resources we observe a competition between polymerization and depolymerization kinetics. Further, it is examined that for a specific range of interaction energy E, the system remains in low density phase, on the contrary, for its significantly higher value, the system transits to high-density phase. In contrast to the high density phase, it is observed that in low density phase, lattice length decreases with an increase in interaction strength. Finally, the theoretical outcomes are validated with extensive Monte Carlo simulations.

A mesoscopic system of dipolar bosons trapped by a harmonic potential is considered. The system has a number of physical realizations including dipole excitons, atoms with large dipolar moment, polar molecules, and Rydberg atoms in inhomogeneous electric field. We carry out a diffusion Monte Carlo simulation to define the quantum properties of a two-dimensional system of trapped dipoles at zero temperature. In dimensionless units the system is described by two control parameters, namely, the number of particles and the strength of the interparticle interaction. We have shown that when the interparticle interaction is strong enough a mesoscopic crystal is formed. As the strength of interactions is decreased a multistage melting takes place. Off-diagonal order in the system is tested using natural-orbitals analysis. We have found that the system might be Bose condensed even in the case of strong interparticle interactions. There is a set of parameters for which a spatially ordered structure is formed while simultaneously the fraction of Bose-condensed particles is nonzero. This might be considered as a realization of a mesoscopic supersolid.

A three-dimensional transient round liquid jet within a low-speed coaxial outer gas flow is numerically simulated and analysed via vortex dynamics ($\unicode[STIX]{x1D706}_{2}$ analysis). Two types of surface deformations are distinguished, which are separated by a large indentation on the jet stem. First, there are those inside the recirculation zone behind the leading cap – directly affecting the cap dynamics and well explained by the local vortices. Second, deformations upstream of the cap are mainly driven by the Kelvin–Helmholtz (KH) instability, unaffected by the vortices in the behind-the-cap region (BCR), and are important in the eventual atomization process. Different atomization mechanisms are identified and are delineated on a gas Weber number ($We_{g}$) versus liquid Reynolds number ($Re_{l}$) map based on the relative gas–liquid velocity. In a frame moving with the liquid velocity, this result is consistent with prior temporal studies. A simpler and clearer portrait of similarity of the atomization domains is shown by using the relative gas–liquid axial velocity, i.e. $We_{r}$ and $Re_{r}$, and avoiding the widely used velocity ratio as a third key parameter. A detailed comparison of vorticity along the axis in an Eulerian frame versus a frame fixed to a surface wave reveals that the vortex development and surface deformations are periodic in the upstream region, but this periodicity is lost closer to the BCR. In the practical range of the density ratio and for early times in the process, axial vorticity is mainly generated by baroclinicity while streamwise vortex stretching becomes more important at later times and only at lower relative velocities when pressure gradients are reduced. The inertia, vortex, pressure, viscous and surface tension forces are analysed to delineate the dominant causes of the three-dimensional instability of the axisymmetric KH structure due to surface acceleration in the axial, radial and azimuthal directions. The inertia force related to the axial gradient of kinetic energy is the main cause of the axial acceleration of the waves, while the azimuthal acceleration is mainly caused by the pressure and viscous forces. The viscous forces are negligible in the radial direction and away from the nozzle exit in the axial direction. It is interesting to note that azimuthal viscous forces are important even at high $Re_{l}$, indicating that inertia is not totally dominant in this instability occurring early in the atomization cascade.

We spectroscopically investigate a pathway for the conversion of 23Na39K Feshbach molecules into rovibronic ground state molecules via stimulated Raman adiabatic passage. Using photoassociation spectroscopy from the diatomic scattering threshold in the a3Σ+ potential, we locate the resonantly mixed electronically excited intermediate states and which, due to their singlet–triplet admixture, serve as an ideal bridge between predominantly a3Σ+ Feshbach molecules and pure X1Σ+ ground state molecules. We investigate their hyperfine structure and present a simple model to determine the singlet–triplet coupling of these states. Using Autler–Townes spectroscopy, we locate the rovibronic ground state of the 23Na39K molecule () and the second rotationally excited state N = 2 to unambiguously identify the ground state. We also extract the effective transition dipole moment from the excited to the ground state. Our investigations result in a fully characterized scheme for the creation of ultracold bosonic 23Na39K ground state molecules.

Core-annular flow of two fluids in down-flow is examined at the onset of a n = ±1 non-axisymmetric instability. This leads to a pattern selection problem; the bifurcating solutions are traveling waves and standing waves. The former travel in the azimuthal direction as well as the axial direction and would be observed as corkscrew waves. The standing waves travel in the axial direction but not in the azimuthal direction and appear as snakes. Weakly nonlinear interactions are studied to see whether one of these waves will be stable to small amplitude perturbations. The corkscrews are found to be preferred when the armulus is narrow and snakes are preferred when the annulus is wide.

Core-annular flow of two fluids is examined at the onset of the azimuthal mode number ±1 non-axisymmetric instability. The patterns that emerge are traveling waves and standing waves. The former travel in the azimuthal direction as well as the axial direction and would be observed as corkscrew waves. The standing waves travel in the axial direction but not in the azimuthal direction and appear as snakes. Weakly nonlinear interactions are studied to see whether one of these waves will be stable to small amplitude perturbations. Sample situations for down-flow are discussed. The corkscrews tend to be preferred when the annulus is narrow, while snakes are more likely when the annulus is wide.KeywordsReynolds NumberStanding WaveMaximum Growth RateFree FallPattern SelectionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

We study non-equilibrium properties of a strongly correlated quantum dot system, represented by the single impurity Andersonmodel, by means of the recently introduced non-equilibrium variational cluster approach [1]. We focus on the steady-state current density and non-equilibrium density of states in a parameter region of high interaction strength in the particle-hole symmetric case, which lies in the center of the Kondo regime. The bias dependent current density shows a gradually developing two peak structure with increasing interaction strength. It agrees with the linear response result in the low bias region and vanishes as expected at high bias due to a vanishing band overlap. The non-equilibrium density of states exhibits a linear splitting of the Kondo resonance with applied bias voltage. We compare results obtained via non-equilibrium variational cluster approach with non-equilibrium cluster perturbation theory.