arXiv subjects

Andreas F. Terzis

Publications and source records attributed to Andreas F. Terzis.

6 recordsLinked to original sources

arXiv2026

Beyond the Unruh vacuum: multi-time correlations in black hole collapse and evaporation

The black hole information paradox originates from the thermal character of Hawking radiation, which appears to erase information about the collapsing matter. However, thermality constrains only observables defined at a single time and leaves the structure of temporal quantum correlations largely unexplored. Here we show that multi-time quantum-field correlations provide a concrete mechanism for the survival of pre-collapse information in black hole evaporation. Using a two-dimensional model of gravitational collapse and evaporation, we demonstrate that late-time multi-time correlations are not fully reproduced by the Unruh vacuum. In particular, they contain a contribution that depends explicitly on parameters characterizing the pre-collapse state, despite the thermal character of the asymptotic radiation. Our results identify measurable multi-time correlations as carriers of information in Hawking radiation and suggest that formulations of the black hole information paradox based solely on single-time observables are incomplete.

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arXiv2023

Aharonov-Bohm effect as a diffusion phenomenon

This paper presents a hydrodynamical view of the Aharonov-Bohm effect, using Nelson's formulation of quantum mechanics. Our aim is to compare our results with other systems and gain a better understanding of the mysteries behind this effect, such as why the motion of a particle is affected in a region where there is no magnetic field. Some theories suggest that this effect is due to the non-local action of the magnetic field on the particle, or even the physical significance of vector potentials over magnetic fields. Our main purpose is to use Nelson's formulation to describe the effect and demonstrate that it can be explained by the direct action of the current surrounding the magnetic field region (i.e. a cylinder) on the particle outside of it. In this context, magnetic fields and vector potentials serve as tools for finding other fundamental quantities that arise from the interaction between two fields: the quantum background fields described by Nelson's quantum theory. Finally, we investigate the relationship between hidden variables and quantum fluctuations and their role in this phenomenon.

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arXiv2017

Generation of maximally entangled states in hybrid two quantum dots mediated by a spherical metal nanoparticle driven by external laser field

We theoretically study the generation of quantum correlations in a hybrid system composed by two interacting semiconductor quantum dots mediated by a metal nanoparticle and coupled to an external laser field. Interactions present in the hybrid system are treated using a semiclassical approximation except for the direct dipole-dipole interaction. We report the entanglement of formation, which gives information about entanglement quantum correlations, for continuous wave and pulsed driving applied fields. We have found that for proper values of the physical and geometrical parameters of the hybrid system the applied field can be tuned producing quantum correlations of significant value so that they can be useful in quantum information and computation processes.

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arXiv2014

Chemical bond and entanglement of electrons in the hydrogen molecule

We theoretically investigate the quantum correlations (in terms of concurrence of indistinguishable electrons) in a prototype molecular system (hydrogen molecule). With the assistance of the standard approximations of the linear combination of atomic orbitals and the configuration interaction methods we describe the electronic wavefunction of the ground state of the H2 molecule. Moreover, we managed to find a rather simple analytic expression for the concurrence (the most used measure of quantum entanglement) of the two electrons when the molecule is in its lowest energy. We have found that concurrence does not really show any relation to the construction of the chemical bond.

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arXiv2014

Polarization-entangled photon generation by a semiconductor quantum dot coupled to a cavity interacting with external fields

We theoretically investigate polarization-entangled photon generation by using a semiconductor quantum dot embedded in a microcavity. The entangled states can be produced by the application of two cross-circularly polarized laser fields. The quantum dot nanostructure is considered as a four-level system (ground, two excitons and bi-exciton states) and the theoretical study relies on the dressed states scheme. The quantum correlations, reported in terms of the entanglement of formation, are extensively studied for several values of the important parameters of the quantum dot system as the bi-exciton binding energy, {the decoherence times of the characteristic transitions, the quality factor of the cavity} and the intensities of the applied fields.

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arXiv2004

Entanglement in a Two-Qubit Ising Model Under a Site-Dependent External Magnetic Field

We investigate the ground state and the thermal entanglement in the two-qubit Ising model interacting with a site-dependent magnetic field. The degree of entanglement is measured by calculating the concurrence. For zero temperature and for certain direction of the applied magnetic field, the quantum phase transition observed under a uniform external magnetic field disappears once a very small non-uniformity is introduced. Furthermore, we have shown analytically and confirmed numerically that once the direction of one of the magnetic field is along the Ising axis then no entangled states can be produced, independently of the degree of non-uniformity of the magnetic fields on each site.

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