International Journal of Theoretical Physics最新文献

Quantum nonlocality is a very important quantum resource. Different types of quantum correlation can present the quantum nonlocality in varying degrees. In this paper, we investigate the dynamic evolution of steered quantum coherence (SQC) for a system of interacting qubits in contact with various models of the environment, and emphatically compare the robustness of SQC and quantum entanglement (QE). The results show that from the given initially state, due to the decoherence effect, both SQC and QE evolve with time in the form of oscillation. In the process of dynamic evolution, the QE will appear death and rebirth for all different decay modes. Differently, the SQC will not emerge the sudden death or the dark and bright, which shows a stronger robustness than QE. Moreover, we find that, under the long-term limit condition, the SQC will approach the steady value in different decay modes, which provides a reliable resource foundation for the completion of quantum information processing.

In this comment, we showed that it is a mistake to work with the Dirac equation in the form presented by Haouam. Indeed, this happens because the Rashba Hamiltonian is a direct result of the non-relativistic limit of the Dirac equation and, therefore, it makes no sense to use such a Hamiltonian in the Dirac Hamiltonian itself, as Haouam did. Therefore, Haouam cannot simply introduce a non-relativistic Hamiltonian into the relativistic Hamiltonian itself in which it originated (this is something physically inconsistent). However, one way to get around this error would be if Haouam had applied his problem to “massive” graphene, where the Dirac equation with the Rashba coupling makes more sense (but it was not the case).

The main objective of this work is to construct novel optical soliton solutions for nematic liquid crystals with conformable derivative using the new Kudryashov approach, a method arising in plasma physics and fluid mechanics. The obtained optical soliton solutions such as W-shape, bell shape, singular, dark-bright, bright, dark, and periodic solutions are explored and expressed by the hyperbolic functions, the exponential functions, and the trigonometric functions to clarify the magnitude of the nematic liquid crystals model with conformable derivative. The resulting traveling wave solutions of the equation play an important role in the energy transport in soliton molecules in liquid crystals. This paper contributes to understanding the fantastic features of nematicons in optics and further disciplines. The kinetic behaviors of the real part, imaginary part, and the square of modulus soliton solutions are illustrated by two-dimensional (2D) and three-dimensional (3D) contours graphs choosing the suitable values of physical parameters. It can be noticed that the novel Kudryashov approach is a powerful tool and efficient technique to solve various types of nonlinear differential equations with fractional and integer orders. That will be extensively used to describe many interesting physical phenomena in the areas of gas dynamics, plasma physics, optics, acoustics, fluid dynamics, classical mechanics.

In this work, we use a monoatomic chain subject to an anharmonic potential with nearest neighbor couplings to derive the discrete nonlinear evolution equation. Thereafter, the modulational instability growth expression is derived by using the linear stability analysis. Our work displays the influence of the interaction potential and nearest neighbor couplings on the modulational instability and bandwidths. As a result, we show that the number of modulational unstable modes increases, while the number of modulational stable modes decreases when certain specific values are taken by the interaction potential. The same observation has been highlighted when the nearest neighbor couplings get high values. A numerical simulation of the continuous wave has been realized to confirm the fact that the modulational instability is sensitive to the nonlinear parameters due to the development of the modulated wave structures and trains of waves. Another particular result of this work has been displayed by driving the left and right ends of the chain into the lower and upper forbidden gaps. Supratransmission thresholds have been derived to get the corresponding driving amplitudes. It emerges that for the driving amplitude above the supratransmission threshold, the modulated waves occur in the lower forbidden frequency gap. At the same time, it results in a chaos-like motion in the propagation range of time in the upper forbidden gap. Such observations confirm the fact that in nonlinear structures, when the driving amplitude is considered above the supratransmission threshold, localized waves (gap solitons) are generated.

In this article, with an overview to the dynamics of the homogeneous and isotropic cosmology for the usual and phantom scalar fields, we investigate the model of exponentially damping fields. We obtain the extract solutions for the potential function, the scale factor of the model and the dynamics of the parameter of the equation of state. We present two proposals for the scalar field to achieve the exponential potential function in terms of time and extract Hubble’s cosmological parameters, scale factor and equation of state parameter for each model. At the end of the work, we turn our attention to the quantum cosmology of the model with time-damped exponential potential and form the Wheeler-Dewitt equation with some new variables. The Wheeler-DeWitt wave packets with the Gaussian weight function are obtained for the scalar fields in different cases and draw the probability function of each one.

I propose, as geometric structure in an internal space, a helical field that is responsible for intrinsic properties of point particles, particularly, electron. For the novel theoretical development, plasma astrophysical analogy is made extensively. Transition between our conventional space and the infinitesimal space is considered in an operational manner. It is shown that rotational eigenvalue equation satisfied by the vector field equivalent to Gromeka-Beltrami flow provides a coordinate-rotor that captures complex orthogonality between the internal coordinate space and isotopic, angular momentum space. Self-consistent normalization of rotational coordinate owing to the rotor is compared to renormalization of electric charge. It is also found that chiral asymmetry of the helical eigenflows can be reflected in electroweak symmetry breaking. The theoretical prototype suggests possible geometrical features of a fundamental framework ruling matters and forces with higher dimensions.

We develope a new method of constraining non-Newtonian gravity at the nanometer range. In this method, we consider a hybrid electro-optomechanical system. By applying a strong driving field, we may obtain normal mode splitting of the electromechanical subsystem. Provided that the Casimir background is suppressed and our system is operated at critical points, by investigating the relationship between this splitting and the resonance frequency of the mechanical oscillator, we set a constraint on the non-Newtonian gravity. This constraint significantly improves the previous bounds at the nanometer range, indicating that the method is considerable.

We investigate solutions to the Tolman-Oppenheimer-Volkoff equations and their implications, deriving an equation of state for the star’s surface as a function of two geometric parameters, (lambda (r)) and (nu (r)). We find that the parameter (lambda (r)) is essential for explaining fluctuations in the baryon number density and baryonic chemical potential within and outside a neutron star, enabling simulations of regions with varying neutron matter densities. We also highlight the significant role of the (nu (r)) parameter for describing the explosive transition of a neutron star to a black hole, establishing a direct connection between the neutron star’s radius and the event horizon’s radius. The parameter (lambda (r)) is crucial for understanding how the baryon number density and baryonic chemical potential fluctuate inside and outside a neutron star. The core is characterized by (lambda >0), and the outer crust is defined by (lambda <0). Finally, by analyzing the polytropic equation of state, we find that the neutron stars are composed of two distinct regions: a low-density outer crust and a very high-density core, separated by a sharp boundary. The mixing region between the two layers is known as the inner crust and outer core.

We investigated the stability of the chameleon screening mechanism in the Brans-Dicke scalar-tensor model. We define a constraint on the Brans-Dicke parameter (varvec{omega }_{BD}^*) identifying two stability groups, (varvec{omega }_{BD}>varvec{omega }_{BD}^*) and (0<varvec{omega }_{BD}<varvec{omega }_{BD}^*). The first group achieves stability with both appropriate eigenvalues and a density profile consistent with dark energy dominance. The second exhibits eigenvalue stability but contradicts conditions for a stable universe. We explore the impact of variations in the scalar field potential and matter coupling by analyzing different parameter sets. Each unique set of parameters results in a distinct (varvec{omega }_{BD}^*). Dynamic analysis reveals that stability is achieved when the scalar field dominates, highlighting the importance of the kinetic and potential terms while minimizing the influence of matter density. In high matter density regions, the scalar field’s negligible presence aligns with standard gravitational behavior, whereas in low matter density regions, the scalar field grows exponentially, driving dark energy and cosmic acceleration.