Enhanced Interactions between Dipolar Polaritons.

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.

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>.

We discuss effects of elastic adsorbate-substrate interactions in processes of nanostructuring of thin films during low-pressure condensation in the framework of theoretical approaches and numerical simulations. It will be shown that an increase in the elastic interaction strength induces first-order transitions and pattern formation. We simulate deposition on one- and multicomponent substrates with different strengths of adsorbate-substrate interactions. We will show that an increase in the strength of adsorbate-substrate interactions stimulates the formation of stable surface structures during deposition, which leads to an increase in its coverage and the formation of a smaller number of adsorbate islands of larger size. At elevated adsorption rates, an increase in adsorbate-substrate interactions results in the transformation of the surface morphology and the formation of percolating adsorbate structures. Deposition onto multicomponent substrates leads to the formation of a stationary surface morphology with an elevated number of adsorbate islands of smaller size, compared to one-component substrates. This study provides a deep insight into the peculiarities of nanostructured thin films' growth in low-pressure systems with different adsorbate-substrate bonding.

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.

Recent experimental progress in magnetic atoms and polar molecules has created the prospect of simulating dipolar Hubbard models with off-site interactions. When applied to real-space cylindrical optical lattices, these anisotropic dipole-dipole interactions acquire a tunable spatially-dependent component while they remain translationally-invariant in the axial direction, creating a sublattice structure in the azimuthal direction. We numerically study how the coexistence of these classes of interactions affects the ground state of hardcore dipolar bosons at half-filling in a finite-size cylindrical optical lattice with octagonal rings. When these two interaction classes cooperate, we find a solid state where the density order is determined by the azimuthal sublattice structure and builds smoothly as the interaction strength increases. For dipole polarisations where the axial interactions are sufficiently repulsive, the repulsion competes with the sublattice structure, significantly increasing entanglement and creating two distinct ordered density patterns. The spatially-varying interactions cause the emergence of these ordered states in small lattices as a function of interaction strength to be staggered according to the azimuthal sublattices.

Output field squeezing in a weakly-driven dissipative quantum Rabi model

The spectral function of a single hole in the two-dimensional Hubbard model is studied numerically through exact diagonalization for a nine-site cluster over a wide range of interaction strengths U. In the weak-interaction limit, the spectral function consists of sharp quasiparticle peaks corresponding to the allowed single-particle excitations of the noninteracting system. As the interaction strength increases, the spectral weight begins to spread over a large range of energies, and satellite structures appear at higher excitation energy. The band-narrowing effect and the quasiparticle weight are investigated. The results are discussed in connection with other analytical and numerical studies on the spectral function.

The collective-excitation spectrum from a filled Landau level in a rotating dipolar Fermi gas is investigated through the equation of motion method. The predicted excitation spectrum exhibits a roton structure which is affected by the strength of dipolar interactions and trapping potential. The correlation effect on the roton minimum is observed by varying the dipolar interaction strength. An increase of the dipolar interaction strength leads to a deeper roton minimum. The roton minimum can even become zero, where the system exhibits instability, as the dipolar strength approaches a critical value. As the dynamical stability of the system is studied through the roton structure, we find that this zero-value roton minimum is a precursor of the occurrence of a bubble crystal.

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.

We consider the effect of electron-electron interactions on a voltage biased quantum point contact in the tunneling regime used as a detector of a nearby qubit. We model the leads of the quantum point contact as Luttinger liquids, incorporate the effects of finite temperature and analyze the detection-induced decoherence rate and the detector efficiency, $Q$. We find that interactions generically reduce the induced decoherence along with the detector's efficiency, and strongly affect the relative strength of the decoherence induced by tunneling and that induced by interactions with the local density. With increasing interaction strength, the regime of quantum-limited detection ($Q=1$) is shifted to increasingly lower temperatures or higher bias voltages respectively. For small to moderate interaction strengths, $Q$ is a monotonously decreasing function of temperature as in the non-interacting case. Surprisingly, for sufficiently strong interactions we identify an intermediate temperature regime where the efficiency of the detector increases with rising temperature.

We analyze a system of interacting arrays of globally coupled nonlinear oscillators. The relaxation in the interacting arrays with different interaction strengths is compared to that in an array not subject to interaction with others. The relaxation of the latter is found to be an exponential function of time. On the other hand the relaxation of the interacting arrays is slowed down and departs from an exponential of time. There exists a crossover time, ${t}_{c}$, before which relaxation of the interacting arrays is still an exponential function. However, beyond ${t}_{c}$ relaxation is no longer exponential but well approximated by a stretched exponential $\mathrm{exp}[\ensuremath{-}{(\frac{t}{\ensuremath{\tau}})}^{\ensuremath{\beta}}]$. The fractional exponent $\ensuremath{\beta}$ decreases further from unity with increasing interaction strength. The result bears strong similarity to the basic features suggested by the coupling model and seen experimentally by neutron scattering for relaxation in densely packed interacting molecules in glass-forming liquids.

Thermophoresis refers to the motion of small particles suspending in a fluid with non-uniform temperature distribution due to the temperature gradient around the particle. Usually, the fluid molecules coming from the hot side carry more kinetic energy than those from the cold side, which results in a net thermophoretic force in the direction opposite to the temperature gradient. Since it was discovered more than 100 years ago, thermophoresis has been of major importance in a variety of applications, where it can play either beneficial role or adverse role, including material synthesis, micro- and nano-fabrication, and environmental science. Therefore, it is necessary to accurately evaluate the thermophoretic force. In the present work, the thermophoretic force on nanoparticles is examined in the free molecule regime by using non-equilibrium molecule dynamics (MD) simulation. It has been widely accepted that the thermophoretic force conforms with the Waldmann equation for large Knudsen numbers. However, due to the effect of the nonrigid-body interactions between the particle and gas molecules, the thermophoretic force on nanoparticles might deviate greatly from the classical theory. In our MD model, a single nanoparticle with a diameter of several nanometers suspends in a diluted gas. The Lennard-Jones (L-J) potential is employed to simulate the intermolecular interactions. To avoid deforming the nanoparticle, the solid molecules within the nanoparticles are linked to their nearest neighbors through a finite extensible nonlinear elastic bonding potential. The thermophoretic force on a nanoparticle is calculated by imposing a harmonic potential on the nanoparticle, which eliminates the effect of the Brownian motion of the nanoparticle on the thermophoresis. The effective thermal conductivity of the ambient gas is employed in Waldmann equation for the thermophoretic force due to the finite volume effect. It is found that the Waldmann theory for thermophoresis is still valid for nanoparticles in the case of weak gas-particle interaction or high gas temperature. With the increase of the gas-particle interaction strength or the decrease of the gas temperature, the Waldmann theory is invalid due to the effect of gas-particle nonrigid-body collisions and the adsorption of gas molecules on the particle surface. By considering the gas-particle nonrigid-body interaction and the modified particle size, the theoretical results for thermophoretic force accord with the MD simulations quite well.