Modern Physics Letters A

In this paper, a channel-optimized quantum communication scheme with imperfect Bell states is being considered, based on quantum teleportation and error correction codes technology. In this scheme, a novel “combination code” technique is proposed to protect the pre-shared Bell states from storage errors and to safeguard the information-encoded states from noisy channels. Ultimately, it is revealed by Monte Carlo simulation results that the channel fidelity of the proposed channel-optimized quantum communication scheme with imperfect Bell states is significantly advantageous over standard quantum error-correcting code (QECC) and entanglement-assisted quantum error-correcting code (EAQECC) communication schemes.

The one-loop contributions to the flavor-changing neutral current decays of the top quark into a light quark and a gauge boson or Higgs boson, namely, $t\to qV,qh$, with q being u or c, and V being $\gamma$, g, or Z, are analyzed in this study within the framework of the minimal R-symmetric supersymmetric standard model. The charginos in this model have been separated into two sets, i.e. $\chi$-chargino and $\rho$-chargino. The numerical results reveal that gluino or $\rho$-chargino predominantly dictate the predictions for BR ($t\to qV,qh$), while the impact of neutralino or $\chi$-chargino contributions is insignificant. By incorporating the constraints imposed by the squark mixing parameters from $\bar{B}\to X_s\gamma$ and $B_{d,s}^0\to {\mu }^{+}{\mu }^{-}$, the theoretical predictions for BR($t\to qg$) can be significantly augmented to approximately $\mathcal{𝒪}(10^{-5}-10^{-6})$. On the other hand, the values of BR($t\to q\gamma ,qZ,qh$) are predicted to be at least four orders of magnitude below the current experimental limits.

Delving into spring-like helical configurations, such as DNA within our cells, motivates physicists to inquire about the effects of such structures in the realm of quantum field theory, specifically unraveling their manifestation of effectiveness in Casimir energy. To explore this, we initiated our investigation with the Casimir effect and proceeded to calculate the Casimir energy, along with its thermal and radiative corrections, for massive and massless Lorentz-violating scalar fields across (d+1)-dimensional spacetime. Adhering to the principle that the renormalization program should be consistent with the boundary conditions applied to the quantum fields was paramount. Accordingly, one-loop correction to the Casimir energy for both massive and massless scalar fields under helical boundary conditions by employing a position-dependent counterterm was performed. Our results, spanning across spatial dimensions, exhibited convergence and coherence with established physical grounds. Additionally, we presented the Casimir energy density using graphical plots for systems featuring time-like and space-like Lorentz violations across all spatial dimensions, followed by a comprehensive discussion of the obtained results.

In order to solve the mystery of the accelerating and expanding universe model first, various dark energy candidates, such as Quintessence, Tachyon, k-essence, Phantom and DBI-essence, were investigated in detail in the $f(Q)$ modified symmetric teleparallel gravitation theory for homogeneous and isotropic FRLW universe model. The $f(Q)=a{Q}^n+b$ model is used to obtain solutions in $f(Q)$ theory. Also, the physical behaviors of some cosmological parameters such as pressure and density were studied. Dark energy candidates were analyzed for different values of n with various graphs.

In this paper, we investigate how the electromagnetic field influences the idea of complexity within the framework of squared gravity. The physical traits, including heat dissipation, charge, anisotropic pressure, energy density variations and correction components are found to be significant contributors of complexity in celestial objects. By employing Herrera’s orthogonal splitting approach, scalar functions are obtained yielding a complexity factor that incorporates the crucial attributes of the self-gravitating system. Furthermore, we examine the dynamics of charged spherical configuration by considering homologous mode as the simplest evolutionary pattern. Our investigation includes complexity-free scenarios (dissipative/non-dissipative) with homologous constraints. Moreover, we explore the components that contribute toward complexity during the evolutionary process. We conclude that self-gravitating structures get more complex with the inclusion of extra curvature terms of squared gravity and charge.

In the region where the gravitational field is strong, we have examined the influence of different gravities on the accretion disk formed due to spherical accretion. To achieve this, we obtain numerical solutions of the GRH equations, utilizing Schwarzschild, Kerr, Einstein–Gauss–Bonnet, and Hartle–Thorne spacetime metrics. We investigate the impact of the rotation parameter of a black hole ($a∕M$), the EGB coupling constant ($\alpha$), and the quadrupole moment of the rotating black hole (q) on the accretion disk formed in a strong field. The formation of the disk for the slowly and rapidly rotating black hole models is separately examined, and comparisons are made. Our numerical simulations reveal that, under the specific conditions, the solution derived from Hartle–Thorne gravity converges toward solutions obtained from Kerr and other gravitational models. In the context of the slowly rotating black hole with $a∕M=0.28$, we observe a favorable agreement between the Hartle–Thorne result and the Kerr result within the range of $0<q<0.5$. Conversely, in the scenario of the rapidly rotating black hole, a more pronounced alignment with the value of $q=1$ is evident within the range of $0.5<q<1$. Nevertheless, for $q>1$, it becomes apparent that the Hartle–Thorne solution diverges from solutions provided by all gravitational models. Our motivation here is to utilize the Hartle–Thorne spacetime metric for the first time in the numerical solutions of the GRH equations for the black holes, compare the results with those obtained using other gravities, and identify under which conditions the Hartle–Thorne solution is compatible with known black hole spacetime metric solutions. This may allow us to provide an alternative perspective in explaining observed X-ray data.

This paper delves into the exploration of quantum resources within a two-qubit system composed of two 2-level atoms connected to distinct thermal baths. Various quantifiers are employed to evaluate different aspects of the system’s quantum characteristics. Specifically, the ${\ell }_1$-norm and relative entropy of coherence (${\mathcal{𝒞}}_{{\ell }_1}$ and ${\mathcal{𝒞}}_r$) are utilized to gauge quantum coherence, while local quantum Fisher information (LQFI) is used to quantify non-classical correlations within the system. The findings suggest that the amount of quantum correlations and coherence decline as the spontaneous emission rate $\gamma t$ and the mean thermal photon number n increase. However, it is observed that manipulating parameters defining the initial state of the two-level atoms system can enhance non-classical correlations and quantum coherence between the two atoms. Additionally, it is noted that these three key metrics entirely vanish in the asymptotic limit of time. Our research underscores the importance of precisely adjusting the parameters of the initial system state, which is prepared in an extended Werner-like state (EWL), to protect quantum resources shared between the two atoms from environmental influences.