arXiv subjects

M. S. Soares

Publications and source records attributed to M. S. Soares.

12 recordsLinked to original sources

arXiv2026

When Bob orbits Alice: entanglement harvesting in circular motion

We study radiative processes of two qubits coupled to a massless scalar field prepared in the Minkowski vacuum state. The analyze the effects of vacuum fluctuations in the generation of qubits' entangled states is performed. We assume one of the qubits is at rest in an inertial frame while the other comoves with a uniformly rotating frame, i.e., undergoing circular motion. We investigate how the entanglement harvesting phenomenon depends on the radius and angular velocity of the non-inertial qubit. We compute the concurrence and mutual information to identify the set of circular motion parameters that maximizes entanglement generation.

hep-th↗

arXiv2026

Soliton dynamics in the Ostrovsky equation with anomalous dispersion

We investigate the formation and interaction of solitons in the non-integrable Ostrovsky equation characterized by anomalous (positive) dispersion. This equation is relevant for describing wave phenomena in various media, including plasma, solids, and optical fibers. Our findings indicate that certain Ostrovsky solitons, which possess zero total ''mass'' and exhibit non-monotonic asymptotic behavior, can arise from initial perturbations of a pulse-like nature. These solitons may organize into regular trains, where they are arranged according to their amplitude, or they may form irregular, nonstationary configurations of bound interacting solitons, or even multi-soliton structures. Furthermore, we demonstrate that the interactions between solitons in the Ostrovsky equation are inelastic, resulting in the emergence of a dominant soliton, or ''soliton-champion,'' within closed systems, such as those with periodic boundary conditions. In such systems, the soliton with the highest amplitude acts as a ''terminator,'' annihilating smaller amplitude solitons and absorbing a portion of their energy. We also analyze the recurrence phenomenon and determine that, although it resembles that of the Korteweg-de Vries equation, it exhibits distinct features.

nlin.PS↗

arXiv2025

A dynamic theory of entanglement for uniformly accelerated atoms

We study the entanglement dynamics of accelerated atoms using the theory of open quantum systems. We consider two atoms travelling along different hyperbolic trajectories with different proper times. We use the generalized master equation to discuss the dynamics of a pair of dipoles interacting with the electromagnetic field. The fundamental role played by proper acceleration in the entanglement harvesting and sudden death phenomenon is discussed. Finally, we discuss how the polarization of the atoms affects our results. For some choices of the polarization's configuration, we no longer observe the entanglement harvesting phenomenon.

hep-th↗

arXiv2025

Time-dependent accelerated Unruh-DeWitt detector without event horizon

We investigate unitarily inequivalent representations of the algebra of operators in quantum field theory in the cases where there is a Fock representation of the commutation relations. We examine more closely the operational definition of a measurement device, discussing the Unruh-DeWitt and Glauber models of quantum detectors. The transition probability per unit of proper time of both detectors in different non-inertial frames of reference in Minkowski spacetime is evaluated. We first study detectors traveling in a stationary worldline with a constant proper acceleration, i.e., a hyperbolic motion, interacting with the field prepared in the Poincaré invariant Fock vacuum state. Next, we study the Unruh-DeWitt detector at rest in a non-uniformly accelerated frame, with a time dependent acceleration interacting with the field in the Poincaré invariant Fock vacuum state. We evaluate the positive frequency Wightman function for the non-uniformly accelerated frame in a finite time interval and find that it is similar to the two-point correlation function of a system in equilibrium with a thermal bath. Calculating the transition rate, the non-uniformly accelerated Unruh-DeWitt detector can be excited even if the scalar field is prepared in the vacuum state.

hep-th↗

arXiv2022

Entanglement dynamics: Generalized master equation for uniformly accelerated two-level systems

We propose a new form for the quantum master equation in the theory of open quantum systems. This new formalism allows one to describe the dynamics of two-level systems moving along different hyperbolic trajectories with distinct proper times. In the Born-Markov approximation, we consider a quantum massless scalar field coupled with two-level systems. Starting from a separable state we show the emergence of entanglement harvesting. For different proper accelerations we verify also the entanglement sudden death.

hep-th↗

arXiv2021

Uniformly accelerated quantum counting detector in Minkowski and Fulling vacuum states

In this work we discuss the process of measurements by a detector in an uniformly accelerated rectilinear motion, interacting linearly with a massive scalar field. The detector model for field quanta is a point-like system with a ground state and a continuum of unbounded states. We employ the Glauber theory of photodetection. In an uniformly accelerated reference frame, the detector, interacting with the field prepared in an arbitrary state of the Rindler Fock space, is excited only by absorption processes. For the uniformly accelerated detector prepared in the ground state, we evaluate the transition probability rate in three important situations. In the first one the field is prepared in an arbitrary state of $n$-Rindler quanta, then we consider a thermal Rindler state at a given temperature $β^{-1}$, and finally the case in which the state of the field is taken to be the Minkowski vacuum. The well-known result that the latter excitation rates are equal is recovered. Accelerated or inertial observer interpretations of the measurements performed by the accelerated detector is presented. Finally, we investigate the behaviour of the detector in a frame which is inertial in the remote past but in the far future becomes uniformly accelerated. For the massless case, we obtain that the transition probability rate of the detector in the far future is tantamount to the analogous quantity for the detector at rest in a non-inertial reference frame interacting with the field prepared in an usual thermal state.

hep-th↗

arXiv2019

Multiplicative Noise in Euclidean Schwarzschild Manifold

We discuss a $λφ^{4}+ρφ^{6}$ scalar field model defined in the Euclidean section of the Schwarzschild solution of the Einstein equations in the presence of multiplicative noise. The multiplicative random noise is a model for fluctuations of the Hawking temperature. We adopt the standard procedure of averaging the noise dependent generating functional of connected correlation functions of the model. The dominant contribution to this quantity is represented by a series of the moments of the generating functional of correlation functions of the system. Positive and negative effective coupling constants appear in these integer moments. Fluctuations in the Hawking temperature are able to generate first-order phase transitions. Using the Gaussian approximation, we compute $\langleφ^{2}\rangle$ for arbitrary values of the strength of the noise. Due to the presence of the multiplicative noise, we show that $\langleφ^{2}\rangle$ near the horizon must be written as a series of the the renormalized two-point correlation functions associated to a free scalar field in Euclidean Rindler manifold.

gr-qc↗

arXiv2003

Diffractive production of dijets by double Pomeron exchange processes

A phenomenological description of diffractive dijet hadroproduction via double Pomeron exchange is presented. This description is based on a modified version of the Ingelman-Schlein model which includes the evolution of the Pomeron structure function and corrections regarding rapidity gap suppression effects. The same quark-dominant Pomeron structure function employed in a previous report to describe diffractive dijet and W production via single Pomeron processes is shown here to yield results consistent with the available data for double Pomeron processes as well.

hep-ph↗

arXiv2003

Diffractive Hadroproduction of Dijets and W's at the Tevatron Collider and the Pomeron Structure Function

Results from a phenomenological analysis of dijet and W hard diffractive hadroproduction at Fermilab Tevatron energies are reported. The theoretical framework employed here is a modified version of the Ingelman-Schlein approach which includes DGLAP-evolved structure functions. Different from what has been achieved by the DESY ep HERA reactions, a reasonable overall description of such diffractive hadron processes is obtained only when a complex, quark-rich Pomeron structure function is employed in the calculation.

hep-ph↗

arXiv1999

Charm Contribution to the Structure Function in Diffractive Deep Inelastic Scattering

The charm contribution to the structure functions of diffractive deep inelastic scattering is considered here within the context of the Ingelman-Schlein model. Numerical estimations of this contribution are made from parametrizations of the HERA data. Influence of the Pomeron flux factor is analized as well as the effect of the shape of the initial parton distribution employed in the calculations. The obtained results indicate that the charm contribution to diffractive deep inelastic process might be large enough to be measured in the HERA experiments.

hep-ph↗

arXiv1999

Analysis on the diffractive production of W's and dijets at the DESY HERA and Fermilab Tevatron colliders

Hadronic processes in which hard diffractive production takes place have been observed and analyzed in collider experiments for several years. The experimental rates of diffractive W's and dijets measured at the Tevatron and the cross sections of diffractively produced dijets recently obtained at the HERA experiment are the object of this analysis. We use the Pomeron structure function obtained from the HERA data by two different approaches to calculate the rates and cross sections for these processes. The comparison of theoretical predictions with the measured values reveals some discrepancies that make evident conceptual difficulties with such approaches. A new version of the Ingelman-Schlein model is proposed as an attempt to overcome such difficulties and make theory and data compatible.

hep-ph↗

arXiv1998

Pomeron Flux Factor and Diffractive W and Jet Rates

Experimental rates of W and dijets diffractively produced at the Tevatron Collider have recently become available. We use parametrizations of the pomeron structure function obtained from HERA data by two different schemes to compare theoretical expectations with the measured rates.

hep-ph↗