Modern Physics Letters A

We investigate cosmological inflation models from Randall–Sundrum brane physics. In particular, we examine certain cosmological parameters for two potentials, being a logarithmical one and open string tachyonic inflation (OSTI). In the presence of the brane tension, we give scalar field constraints providing inflationary models matching with Planck results. Then, we discuss the reheating phase of such models. Precisely, the reheating temperature depends on the potential forms. Among others, we find that OSTI provides small temperatures, supported by GUT scales.

The phase space analysis has been used to probe the accelerated expansion of the Universe when $\omega (q)$ dark energy interacts with cold dark matter. Non-gravitational interactions $Q=3Hbq{\rho }_{\mathrm{\text{de}}}$ and $Q=3Hbq{\rho }_{\mathrm{\text{dm}}}$ considered in this work are one of the first models of sign changing interactions that appeared in the literature. Specific $\omega (q)={\omega }_0+{\omega }_{1}q$ dark energy model with $P_{\mathrm{\text{de}}}=\omega (q){\rho }_{\mathrm{\text{de}}}$ has been assumed and all late time scaling attractors have been found. This is a two-parameter model with ${\omega }_0$ and ${\omega }_1$ parameters to be determined, while $q$ is the deceleration parameter. In general the motivation to consider similar fluid models is directly related to the attempts to unify dark energy and dark matter involving the properties of the deceleration parameter. The previous study using similar dark energy model showed that the BOSS result for the expansion rate at $z=2.34$ can be explained without interaction with cold dark matter. In this way, the previous result provides a reasonable basis to organize future studies in this direction. This study is one of the first attempts in this direction. It should be mentioned that the full comparison of the models with observation data and the classification of future singularities have been left as a subject of a forthcoming paper. There are several ways that the model can be extended which also has been left as a subject of a forthcoming paper.

We investigate the existence and stability of both the timelike and null circular orbits for a (2 + 1)-dimensional charged BTZ black hole in Einstein-nonlinear Maxwell gravity with a negative cosmological constant. The stability analysis of orbits is performed to study the possibility of chaos in geodesic motion for a special case of black hole so-called conformally invariant Maxwell spacetime. The computations of both proper time Lyapunov exponent $({\lambda }_p)$ and coordinate time Lyapunov exponent $({\lambda }_c)$ are useful to determine the stability of these circular orbits. We observe the behavior of the ratio $({\lambda }_p/{\lambda }_c)$ as a function of radius of circular orbits for the timelike case in view of different values of charge parameter. However, for the null case, we calculate only the coordinate time Lyapunov exponent $({\lambda }_c)$ as there is no proper time for massless test particles. More specifically, we further analyze the behavior of the ratio of ${\lambda }_{\mathrm{\text{Null}}}$ to angular frequency $({\mathrm{\Omega }}_c)$, so-called instability exponent as a function of charge $(q)$ and parameter related to cosmological constant $(l)$ for the particular values of other parameters.

Various observations from cosmic microwave background radiation (CMBR), type Ia supernova and baryon acoustic oscillations (BAO) are strongly suggestive of an accelerated expansion of the universe which can be explained by the presence of mysterious energy known as dark energy. The quintessential matter coupled with gravity minimally is considered one of the possible candidates to represent the presence of such dark energy in our universe. In view of this scenario, we study the geodesic of massless particles as well as massive particles around a (2 + 1)-dimensional BTZ black hole (BH) spacetime surrounded by the quintessence. The effect of parameters involved in the deflection of light by such a BH spacetime is investigated in detail. The results obtained are then compared with a usual non-rotating BTZ BH spacetime.

Within the framework of quantum gravity and modified entropy-area formalism, the Tsallis holographic dark energy is an effort to peep into a mysterious content of the Universe, the dark energy, to analyze its nature. The Tsallis parameter $\delta$ provides the main characteristic of the Tsallis holographic dark energy. Opting the value of Tsallis parameter $\delta \le 2$, a quintessence scalar field description of the Tsallis holographic dark energy model can be obtained. In this work, we present this quintessential explanation of the Tsallis holographic dark energy with $\delta \le 2$ and reconstruct the dynamics of the scalar field and the potential of quintessence.

The $N$-qubit Greenberger–Horne–Zeilinger (GHZ) states are the maximally entangled states of $N$ qubits, which have had many important applications in quantum information processing, such as quantum key distribution and quantum secret sharing. Thus how to distinguish the GHZ states from other quantum states becomes a significant problem. In this work, by presenting a family of the generalized Clauser–Horne–Shimony–Holt (CHSH) inequality, we show that the $N$-qubit GHZ states can be indeed identified by the maximal violations of the generalized CHSH inequality under some specific measurement settings. The generalized CHSH inequality is simple and contains only four correlation functions for any $N$-qubit system, thus has the merit of facilitating experimental verification. Furthermore, we present a quantum phenomenon of robust violations of the generalized CHSH inequality in which the maximal violation of Bell’s inequality can be robust under some specific noises adding to the $N$-qubit GHZ states.

The present work proposes a scheme to teleport a tripartite coherent state using an unparalleled four-component state as a quantum channel. The scheme involves linear optical devices like beam splitters and phase shifters. It is shown that, even by taking an uncompromising quantum model, almost a complete teleportation can be achieved with an impressive number of photons. It is also shown that the teleportation fails only if zero photons are found in all the three output modes or zero in two output modes and a nonzero even/odd photon in one mode. However, the probability of getting these output modes is almost negligible.