International Journal of Theoretical Physics最新文献

In this article one introduces a formalism of classical mechanics where complex Lagrangian functions are admitted. The results include complex versions of the Lagrangian function, of the Euler-Lagrange equation, of the Hamilton principle, a geometric formulation, and the relation to a previous complex Hamiltonian formalism. The framework is particularly suitable for non-stationary motion, and various pathways can be followed in future investigation.

In this study, we investigate the (2+1)-dimensional generalized Benjamin-Ono equation, a model relevant in fluid dynamics, nonlinear optics, and plasma physics. Our primary aim is to analyse the equation using Lie group theory and derive exact solutions that capture its dynamic behaviours. We first determine the Lie point symmetries of the equation and compute their commutator and adjoint representations. Using these symmetries, we perform reductions that facilitate the construction of closed-form solutions via different ansatz methods. These yield solutions expressed in diverse functional forms such as Jacobi elliptic, hyperbolic, rational, exponential, and trigonometric functions, which are central to nonlinear science and engineering applications. To aid interpretation, we present visual analyses of the solutions via 3D, 2D, and density plots. With appropriate parameter choices, these graphs illustrate wave behaviours. Finally, conserved vectors of the model are derived using Ibragimov’s theorem, offering insight into the system’s underlying conservation laws.

In this paper, we study the noncommutative Dirac field in (1+1)-dimensional Rindler spacetime. An exact solution to the wave equation is obtained. Using Bogoliubov transformations, the pair creation probability and the density of created particles are calculated. Our results show that, in a noncommutative curved spacetime background, the rate of particle creation is inversely proportional to the noncommutativity scale in a manner consistent with the principles of quantum mechanics.

The Landau–Ginzburg–Higgs equation, which arises within the framework of superfluids and Bose–Einstein condensates, is currently under investigation. The main objectives of this study are to obtain novel exact solutions using two analytical techniques and to analyze the corresponding phase portraits. The derived solutions include kink, anti-kink, dark, bright, singular, periodic singular, and complexion soliton solutions. Moreover, the complexion solutions incorporate various types of solitons, such as kink, anti-kink, bright, and dark solitons. The phase portraits of the studied equation are presented to illustrate the system’s dynamical behavior. Furthermore, a perturbation term is introduced into the system to investigate periodic, quasi-periodic, and chaotic motions via Poincaré sections. The stability of the obtained soliton solutions is also examined to ensure their physical relevance. In addition, two-dimensional and three-dimensional simulations are performed to visualize the solutions of the Landau–Ginzburg–Higgs equation, thereby enhancing the understanding of their dynamical and physical characteristics.

We study a hybrid magnomechanical system (HMMS) with two microwave cavities, each containing a YIG sphere, with an ensemble of atoms placed at the intersection of the cavities. We obtain indirect bipartite entanglement across several subsystems (Phonon mode of YIG-1 and magnon-2, Phonon mode of YIG-1 and cavity-2 mode, magnon-1 and cavity-2 modes, magnon-1 and magnon-2 modes, magnon-2 and cavity-1 modes, and cavity-1 and cavity-2 modes). We use logarithmic negativity as an entanglement metric to study the steady-state Gaussian correlations in the linearized coupling regime and investigate the effects of temperature, coupling strengths, and cavity detuning. In this work, we do not study the direct entanglement with other subsystems, but we conclude that the atomic ensemble greatly improves long-range entanglement by allowing coherent exchange between the two cavities, and generated bipartite entanglement remains robust up to experimentally accessible temperature ranges. Non-local quantum correlations in HMMS may be achieved in a unique and versatile manner using the suggested method, with potential applications spanning scalable quantum networks and on-chip quantum information processing.

The Big Bounce model provides an alternative to the classical Big Bang theory. It posits a cyclic universe with phases of contraction and expansion. This raises questions about the preservation of quantum information across these cosmological cycles. In this work, we explore the Quantum Information Theory based on a double Hilbert space framework and a quantum channel. We investigate how information is transferred from the pre-bounce to the post-bounce phase. Analytical and numerical solutions are presented to demonstrate how quantum information, particularly entanglement and coherence, is impacted by different types of quantum noise, such as depolarizing and amplitude damping channels. Our findings suggest that while quantum noise affect information preservation, the use of quantum channels provides a method for analyzing and potentially mitigating information loss.

This work investigates the quantum information metrics—specifically, Shannon information for a two-dimensional relativistic fermionic system with nonminimal coupling to an external electromagnetic field. Starting from a modified Dirac equation derived from a Lorentz-symmetry breaking Lagrangian, we obtain the non-relativistic limit and analyze the resulting effective Schrödinger equation under uniform magnetic fields. The modified Landau quantization reveals energy levels renormalized by the nonminimal coupling parameter g, with eigenfunctions characterized by confluent hypergeometric profiles. We compute the Shannon entropy for the quantized states, demonstrating how g modulates spatial localization and informational uncertainty. The interaction between magnetic field strength and g induces tunable shifts in these information-theoretic quantities, reflecting enhanced or suppressed spin-orbit interactions.

In this paper, inspired by an objective view of the wavefunction, we consider the many worlds in quantum mechanics as an interpretation of the measurement process. Especially, we discuss, heuristically, the emergence scenario of the classical reality from the observer’s perspective within the branching of the universal wavefunction into decoherent states under the inevitable effect of the environment. The questions regarding the probablity, energy conservation and entropy behavior according to such non-interacting worlds are also dealt with.

The present study explores how the quadratic form of the Generalized Uncertainty Principle (GUP) modifies the thermodynamic and transport properties of an ideal Quark–Gluon Plasma (QGP). By incorporating GUP-induced minimal length effects into the statistical framework, we analyze the behavior of the entropy density, the speed of sound, and the ratio between bulk and shear viscosities. Our findings show that, in the limit of a vanishing deformation parameter ((varvec{beta rightarrow 0})), the standard results for an ideal gas of massless, noninteracting particles are naturally recovered: the entropy scales as (varvec{s propto T^3}), the squared speed of sound approaches (varvec{c_s^2 = 1/3}), and the bulk viscosity tends to zero. However, when GUP corrections become significant at high temperatures, the thermodynamic response of the plasma changes markedly. The modified dispersion relations lead to a reduction in the speed of sound, approaching (varvec{c_s^2 simeq 1/5}) in the asymptotic regime, while the bulk-to-shear viscosity ratio increases according to (varvec{zeta /eta propto beta ^2 T^4}). These results suggest that the quadratic GUP introduces an intrinsic quantum-gravitational scale that explicitly breaks conformal symmetry in the QGP and could imprint observable signatures in the high-temperature phase of strongly interacting matter.

We investigate theoretically the improvement of the entanglement between the indirectly coupled two magnon modes in a magnomechanical system with magnon squeezing. We quantify the degree of entanglement via logarithmic negativity between two magnon modes. We show a significant enhancement of entanglement via magnon squeezing. Additionally, the entanglement of two magnons decreases monotonically under thermal effects. We demonstrate that with an increasing photon tunneling rate, entanglement is robust and resistant to thermal effects. We use purity as a witness to the mixing between the two magnon modes. We show that synchronization and purity are very robust against thermal effects rather than entanglement. We examine the relationship between quantum entanglement, purity, and quantum synchronization in both steady and dynamic states. According to our results, this scheme could be a promising platform for studying macroscopic quantum phenomena.