Quantum information analysis of the dirac oscillator in a spinning cosmic string space–time under external magnetic fields

We investigate anomalous oscillations due to the Aharonov–Bohm (AB) and Aharonov–Casher (AC) effects of the one-dimensional Hubbard ring with flux in the strong coupling limit. By using the exact diagonalization method and the Shiba transformation, we examine the energies of the ground-state and a few excited states in the presence of the flux producing the AB or AC effect, where the transformation not only reverses the sign of the interaction U but also exchanges the role between the AB and AC effects in the model Hamiltonian. We systematically classify the AB and AC oscillations by using the number of minima Nmin of the ground-state energy as a function of a normalized phase shift ϕ for 0 ≤ ϕ < 1, and clarify the close relationship between the AB and AC effects. For example, it is shown that Nmin is given by NL − Ne (NL − N↑ + N↓) for the AB (AC) effect in the very strong attraction, where NL, Ne, N↑, and N↓ are the system size, the total number of electrons, the number of electrons with up-spin, and the number of electrons with down-spin, respectively, under the condition of NL > Ne > N↓ > N↑. In more special cases, such as for a half-filled band and the spin-balanced case (NL = Ne and N↓ = N↑), we find Nmin to be 0 (2) for the AB (AC) effect in the case of very strong repulsion. These results show us the nature of interesting phenomena originating from the interplay between the strong correlation and the quantum interference effect in a mesoscopic ring.

In this article, we study topological and noninertial effects on the motion of the two-dimensional Dirac oscillator in the presence of a uniform magnetic field and the Aharonov-Bohm potential. We obtain the Dirac equation that describes the model. Expressions for the wave functions and energy spectrum are derived. The energy spectrum of the oscillator as a function of the various physical parameters involved in the problem is rigorously studied. Finally, we present some analogies between our results and others of the condensed matter physics.

The Symmetries of Quantum and Classical Information. The Ressurected “Ether" of Quantum Information

In periodically-driven quantum systems, resonances can induce exotic nonequilibrium behavior and new phases of matter without static analog. We report on the emergence of fractional and integer resonances in a broad class of many-body Hamiltonians with a modulated hopping with a frequency that is either a fraction or an integer of the on-site interaction. We contend that there is a fundamental difference between these resonances when interactions bring the system to a Floquet prethermal state. Second-order processes dominate the dynamics in the fractional resonance case, leading to less entanglement and more localized quantum states than in the integer resonance case dominated by first-order processes. We demonstrate the dominating emergence of fractional resonances using the Magnus expansion of the effective Hamiltonian and quantify their effects on the many-body dynamics via quantum states' von Neumann entropy and Loschmidt echo. Our findings reveal novel features of the nonequilibrium quantum many-body system, such as the coexistence of Floquet prethermalization and localization, that may allow to development of quantum memories for quantum technologies and quantum information processing.

By considering the cosmic string space–time, we study the interaction of a spinless electrically charged particle with the uniform magnetic field in the region outside the magnetic quantum dot. We show that the missing magnetic flux is influenced by the topology of the cosmic string. In addition, we obtain the Landau levels by assuming that an impenetrable potential wall is located at the radius [Formula: see text] of the cylinder that defines the magnetic quantum dot. Then, we show that an Aharonov–Bohm-type effect for bound states can be achieved from the cosmic string space–time topology and the missing magnetic flux. Further, we extend our discussion to the magnetization and persistent currents at zero temperature.

In this study, we analyze the energy level of the diatomic molecules in the case of a non-relativistic quantum system influenced by an external magnetic field and exponential potential. The energy eigenvalue as the solution of the Schrödinger equation in the cosmic-string spacetime was simulated numerically. The energy spectrum was calculated for the three selected diatomic molecules involving RbH, NI, ScI. The influence of the quantum number, potential parameter, and the external magnetic field is considered in this computation to recover the behavior of the particle. The results showed that the energy value depends on the quantum number, potential parameter, mass of the molecule, and magnetic field strength. The magnetic field strength and the potential parameter most apparently affect the change in energy level, followed by the quantum number which also affects the increase in the energy level of the particle considered in this system. In addition, these results may be useful in studying the thermodynamic, optic, and magnetic properties of the atomic interaction of a system particle. Keywords: Non-relativistic system; Diatomic molecule; Position-dependent mass; External magnetic field; Cosmic string

Diverse forms of nonlinearity within stochastic equations give rise to varying dynamics in processes, which may influence the behavior of extreme values. This study focuses on two nonlinear models of the discrete Langevin equation: one with a fixed diffusion function (M1) and the other with a fixed marginal distribution (M2), both characterized by a nonlinearity parameter. Extremes are defined according to the run theory with thresholds based on percentiles. The behavior of inter-extreme times and run lengths is examined by employing Fisher's Information Measure and the Shannon Entropy. Our findings reveal a clear relationship between the entropic and informational measures and the nonlinearity of model M1-these measures decrease as the nonlinearity parameter increases. Similar relationships are evident for the M2 model, albeit to a lesser extent, even though the background data's marginal distribution remains unaffected by this parameter. As thresholds increase, both the values of Fisher's Information Measure and the Shannon Entropy also increase.

Shannon entropy and Fisher information are pivotal in the information theory area. The presence of outliers in data and using an inappropriate model may cause misleading inferential results in the amount of information. Our aim of this paper is to compute the amount of Shannon entropy and Fisher information that exists in the Pareto distribution in the presence of multiple outliers. Unlike the existing methods in the literature, we present a good method for the estimation of Shannon entropy and Fisher information to cope with the allowing for the possibility of outliers. In this regard, we focus on the Bayesian approach proposed by D. P. Scollnik (A Pareto scale-inflated outlier model and its Bayesian analysis, Scandinavian Actuarial Journal, vol. 2015, no. 3, pp.201–220) , based on the contaminated Pareto distribution. We implement the Gibbs sampler which is a simple and rational method for computing Bayesian estimation of Shannon entropy and Fisher information under different loss functions. Some simulation studies are conducted to investigate the performance of the proposed methodology under various sample sizes and the number of outliers. In the end, two examples of real insurance claim data are studied to illustrate the superiority of the proposed model in analyzing datasets and computing the amount of Shannon entropy and Fisher information.

The Aharonov–Casher (AC) effect is due to the interaction between an electric field and a moving particle that is endowed with a magnetic moment. This interaction is normally, but controversially, introduced by hand and by appeal to electromagnetic symmetry, as first done by Aharonov and Casher. We show here that the AC interaction arises rigorously within quantum electrodynamics (QED) in the Power–Zienau–Woolley formulation, provided that the centre of mass-energy is used as the multipolar reference centre, rather than its strictly non-relativistic limit—the centre of mass.

An analysis of Brazilian agricultural commodities using permutation – information theory quantifiers: The influence of food crisis

We present a novel weather analysis of San Francisco from 2009 to 2019 using concepts from quantum information theory. We describe how to transform a classical weather dataset into a quantum-inspired analytical framework by treating it as a quantum information system embedded in a quantum-like representation, with data encoded as density matrices in Hilbert space. Transforming classical weather data into quantum states is a mathematical abstraction, whereas a quantum-inspired system is not a quantum-physical system. We study a quantum-inspired analytical framework using quantum information-theoretic metrics, including fidelity, classical information, quantum information, decoherent information, Shannon and von Neumann entropies, and the quantum stability index, to represent and analyze the dataset. Furthermore, we give predictions for each quantum information metric for 2020 and 2021. We fit Fourier-series models to the metrics to explore temporal patterns and structural properties in the data.

We consider the class of space–time defects investigated by Puntigam and Soleng. These defects describe space–time dislocations and disclinations (cosmic strings) and are in close correspondence with the actual defects that arise in crystals and metals. It is known that in such materials dislocations and disclinations require a small and large amount of energy, respectively, to be created. The present analysis is carried out in the context of the teleparallel equivalent of general relativity (TEGR). We evaluate the gravitational energy of these space–time defects in the framework of the TEGR and find that there is an analogy between defects in space–time and in continuum material systems: the total gravitational energy of space–time dislocations and disclinations (considered as idealized defects) is zero and infinite, respectively.

Semiconductor quantum dot (QD) structures can be used as a model for understanding the effect of the microscopic structure, symmetry of crystals, and molecules on their macroscopic properties. In this work, the results of two theoretical approaches demonstrate that the spin dynamics in ordered QD structures depends on the size, spatial configuration, and topology of the object built of QDs. It was shown that the spin dynamics in QD structures with the hopping regime of conductivity significantly differs from the spin dynamics in two-dimensional (2D) and three-dimensional (3D) structures being at the other side of the metal-insulator transition. The special character of the effective magnetic field $\ensuremath{\delta}\mathbf{H}$ fluctuations appearing only during tunneling between quantum dots is responsible for the insensitivity of spin relaxation times to the magnitude of the external magnetic field in infinite QD structures (2D square lattice and 1D linear QD chain). In finite QD structures (QD rings and linear chains), an external magnetic field ${\mathbf{H}}_{0}$ is directly involved in the spin relaxation process and spin is lost due to interaction with a special combination of fields $\mathrm{\ensuremath{\Delta}}\mathbf{H}\ensuremath{\sim}[{\mathbf{H}}_{\mathbf{0}}\ifmmode\times\else\texttimes\fi{}\ensuremath{\delta}\mathbf{H}]/\ensuremath{\delta}H$ that leads to an unusual orientation dependence of ESR linewidth, recently observed for QD chains. It was shown that the ordering of QD structures can be used for the conservation of spin orientation. For 1D finite quantum dot chains, the ordering can provide the stabilization of all spin components ${S}_{x},{S}_{y}$, and ${S}_{z}$, while for ringlike molecules only ${S}_{z}$ polarization can be stabilized. The results obtained in this work can be useful for development of novel semiconductor devices and in quantum information processing.

In this work, we proposed a simple model for control of subluminal and superluminal light propagation via an external magnetic field in a lambda configuration degenerate two-level atomic medium. We show that the absorption-dispersion properties and group index under the influence of the strength of coupling laser and external magnetic fields are controlled. By changing the direction and magnitude of the magnetic field, the medium switches from transparency with normal dispersion to enhanced absorption with anomalous dispersion at the line center, corresponding with the transfer from slow light to fast light. This work may provide for the application realization of magneto-optic switches and storage devices in quantum information processing.

Fisher information of a single qubit interacts with a spin-qubit in the presence of a magnetic field