Quantum Viewpoint Research Articles

Scalar Field Cosmology: Classical and Quantum Viewpoints

Scalar Field Cosmology: Classical and Quantum Viewpoints

Quantum Resonance with the Mind: a Comparative Analysis of Buddhism's Eighth Consciousness, Quantum Holography and Jung's Collective Unconscious

This interdisciplinary exploration discusses the intricate conceptual linkages among Buddhism’s Eighth State of Consciousness, Quantum Holography, and the Jungian Collective Unconscious. Central to this study is examining the Eighth Consciousness in Buddhist thought—a realm that transcends the conventional sensory and mental states to connect with a more universal and profound awareness. Drawing parallels, Quantum Holography posits that every part of the universe retains information about the whole, much like a hologram. This notion seemingly mirrors the Jungian concept of the Collective Unconscious, which postulates a shared reservoir of memories and ideas across humanity. The paper contends that the intricate dance of photons, oscillating between particle and wave states, mediates perception through resonance and hints at a multi-layered consciousness stratum that mirrors the vast, enigmatic quantum reality expanse. The study illuminates the intersections and divergences among these frameworks through meticulous comparative analysis, positing that an integrative understanding of quantum theories and Buddhist wisdom can unravel the human psyche’s profound depths. By weaving Eastern philosophies with the Western psychological and quantum theoretical tapestry, the discourse unveils a multifaceted consciousness comprehension, championing integrative approaches as invaluable tools for decoding the mind and universe's enigmatic interplay from a quantum viewpoint.

Quantum problem of the potential of a ring charged on the symmetry axis

Abstract In this work we discuss about the problem of an electrically charged particle placed on the symmetry axis of an electrically charged ring in a quantum viewpoint. This problem should be an expanded version of the usual quantum ring and quantum corral. For this purpose, we present a detailed and pedagogical review about a version of the quantum ring focusing in mathematical aspects. As a new result, we calculate numerically the spectrum and wave functions related to charged particle located on the symmetry axis of charged ring and respective wave functions using two different ways: Numerov and perturbative method.

Revisiting the Concept of Nuclear Rotation: Quantum and Classical Viewpoints

Published from 1956, the Bulgarian Journal of Physics accepts articles in the fields of: General and Mathematical Physics; Particle Physics and Field Theory; Atomic and Molecular Physics; Nuclear Physics; Fundamental Areas of Phenomenology; Theory of Relativity and Astrophysics; Condensed Matter, Statistical Physics; Cross-Disciplinary Physics; and Related Areas of Science and Technology.

Towards ultimate bandwidth photon sources based on Compton backscattering: Design constraints due to nonlinear effects

Nuclear resonance fluorescence experiments typically require high rates of monochromatic photons due to the narrow linewidth of these resonances. Inverse Compton scattering sources are used to perform these experiments. Their intrinsic excellent monochromaticity is however spoiled by a variety of unavoidable imperfections related to the electron and laser beams. Some projects aim at reaching one per-mille of energy bandwidth, which requires attaining excellent brilliance of the electron beam but also a careful optimization of the laser-beam parameters. In particular, in such a situation, a careful accounting for the nonlinearities induced by a relatively large laser energy has to be considered. In this article, we revisit these nonlinearities with a quantum viewpoint with the goal to provide analytical expressions that can be employed for a very fast optimization of the performance of the source. These expressions were benchmarked against the CAIN event generator with an excellent accuracy in the parameters hypervolume that is of interest in this context. We also show that previously published expression often used to include laser nonlinearities in analytical bandwidth expressions significantly depart from the detailed CAIN simulations. The obtained expression are further used to optimize designs similar to those considered in on-going projects.

From Riemannian Trichromacy to Quantum Color Opponency via Hyperbolicity

We propose a mathematical description of human color perception that relies on a hyperbolic structure of the space \({\mathcal {P}}\) of perceived colors. We show that hyperbolicity allows us to reconcile both trichromaticity, from a Riemannian point of view, and color opponency, from a quantum viewpoint. In particular, we will underline how the opponent behavior can be represented by a rebit, a real analog of a qubit, whose state space is endowed with the Hilbert metric.

Propagation Properties of Bound Electromagnetic Field: Classical and Quantum Viewpoints

The present work is motivated by recent experiments aimed to measure the propagation velocity of bound electromagnetic (EM) field (Missevitch, et al. in EPL 93:64004, 2011; de Sangro et al. in Eur Phys J C 75:137, 2015) that reveal no retardation in the absence of EM radiation. We show how these findings can be incorporated into the mathematical structure of special relativity theory that allows us to reconsider some selected problems of classical and quantum electrodynamics. In particular, we come to the conclusion that the total four-momentum for a classical system “particles plus fields” ought to be a present state function of moving charges if EM radiation is negligible. In quantum domain, we analyze novel definition of the momentum operator recently suggested in the study of quantum phase effects (Kholmetskii et al. in Sci. Rep. 8:11937, 2018). It implies that bound EM field energy and momentum are to be present state functions, too. Being in agreement with reported experiments, these conclusions suggest the necessity to carry out more precise experimental verifications for additional and independent determination of propagation properties of bound EM fields. A scheme of a possible experiment on this subject is also proposed.

Thermal stability and electronic properties of boron nitride nanoflakes.

Nowadays, boron nitride has attracted a great deal of attention due to its physical (chemical) properties, facile synthesis, and experimental characterization, indicating great potential for industrial application. Based on this, we develop here a theoretical study on boron nitride nanoflakes built-up from hexagonal boron nitride nanosheets exhibiting hexagonal, rectangular, and triangular shapes. In order to investigate geometry effects such as those due to the presence of armchair and zigzag edges and distinct shapes, we analyzed their properties from both classical and quantum viewpoints. Using classical molecular dynamics calculations, we show that the nanosheets preserve their structural stability at high temperatures, while DFT calculations demonstrate HOMO-LUMO energy gap variation within the theoretical energy gaps of h-BN in bulk and 2D crystals. Besides that, we have also found that boron nitride nanoflakes structures have spatially symmetrical spin densities.

Weak gravitational interaction of fermions: Quantum viewpoint

Using the quantum theory of linearized gravity, gravitational interaction differential cross-sections of one fermion by another fermion, a photon and a scalar particle are calculated in the fermion rest frame. Then, according to the obtained results, it is shown that in the lab frame, the gravitational interaction depends on the spin of the moving particle and is independent of the spin of the rest particle. After that, on the dependency of the gravitational interaction of fermion–photon upon the various states of photons, polarization is discussed.

Hidden Information, Energy Dispersion and Disorder: Does Entropy Really Measure Disorder?

Despite its appearance in physics around the 1850th, the second law of thermodynamics is still attracting more efforts to be clarified. More specifically, fifteen years later (1865) after its definition and introduction, entropy has been the subject of various interpretations. Hence, in physical sciences and notably in different education levels, its concept seems to be relatively tough to unambiguous decipher. In this work, we re-introduce the notion of entropy from classical, quantum and information theories viewpoints. The controversial over entropy and a measure of disorder misconception, stated by many scientists, is addressed as well to come up with less confusing physical interpretation of entropy. Hence, over time, an increase of entropy, a quantitative quantity, is most often associated to a rising of disorder, a non-quantitative quantity and no value-returning mathematical equation, rather than a continuously increasing of hidden data. In other words, linking disorder to hidden data is typically raising more confusion than clarification. Here, we shed more light on both concepts to find out an acceptable interpretation of entropy.

Quorum sensing: a quantum perspective.

Quorum sensing is the efficient mode of communication in the bacterial world. After a lot of advancements in the classical theory of quorum sensing few basic questions of quorum sensing still remain unanswered. The sufficient progresses in quantum biology demands to explain these questions from the quantum perspective as non trivial quantum effects already have manifested in various biological processes like photosynthesis, magneto-reception etc. Therefore, it's the time to review the bacterial communications from the quantum view point. In this article we carefully accumulate the latest results and arguments to strengthen quantum biology through the addition of quorum sensing mechanism in the light of quantum mechanics.

Electromagnetic propagation across a metal: the causal propagator

The very general expression of the Schwinger–Feynman causal propagator is explicitly derived for the transmission of a photon through a metal from air, as a generalization of our earlier work dealing with dielectrics. In a very general context, the corresponding transition amplitudes for crossing through the metal of a polarized or unpolarized photon are obtained. Inspired by Feynman’s intuitive and well-publicized non-technical treatment, we consider, from a quantum viewpoint, the fate of a red and a blue photon in determining their transmission probabilities, as an application, through a thin layer of silver whose complex dielectric function, in particular, has been experimentally carefully determined in recent years. Particular emphasis is also put in assessing the accuracy of the phenomenological expression of exponential damping used in considering transmissions through metals in comparison to the exact expressions obtained in the bulk of the paper.

Quantum viewpoint of quadratic f(R) gravity, constraints, vacuum-to-vacuum transition amplitude and particle content

We investigate, from a quantum viewpoint, the nature of the linearized quadratic \(f(R)=(R+aR^2)\)-gravity. To derive the explicit expression of the underlying propagator of the theory, the field is coupled to an external energy–momentum \(T^{\mu \nu }\), and an auxiliary field is introduced to deal with gauge constraints as done in gauge theories. In particular for a conserved \(T^{\mu \nu }\), we establish the gauge invariance of the vacuum-to-vacuum transition amplitude \(\langle 0_+|0_-\rangle \), and prove the necessary positivity condition \(|\langle 0_+|0_-\rangle |^2 0\), required by the quantum theory aspect of the treatment. An exact expression is then derived of the number of particles emitted, at a given energy, by a circularly oscillating Nambu string from which we may compare the relative number of the spin 0 massive particles emitted to the graviton number which turns up to give a clear cut departure from the general relativity prediction.

Quantum and Classical Characterization of Single/Few Photon Detectors

This paper's purpose is to review the results recently obtained in the Quantum Optics labs of the National Institute of Metrological Research (INRIM) in the field of single- and few-photon detectors calibration, from both the classical and quantum viewpoint. In the first part of the paper is presented the calibration of a single-photon detector with absolute methods, while in the second part we focus on photon-number-resolving detectors, discussing both the classical and quantum characterization of such devices.

Red light, blue light, Feynman and a layer of glass: the causal propagator

A propagator–description approach of the propagation of EM waves is provided, in complex situations with underlying boundary conditions. To this end, the so-called Schwinger–Feynman causal propagator is explicitly derived, and spelled out, for the first time, for transmission of a photon through, and reflection off, a layer of glass of flat parallel surfaces. In a very general context, the corresponding transition amplitudes of a polarized or unpolarized photon are obtained, and the conservation of probabilities, and the underlying consistency conditions of the results, are established. Inspired by Feynman’s intuitive and well-publicized non-technical treatment of such a problem with red and blue light, one, in a quantum view-point, is interested in the probabilities of the events just described in determining the fate of a photon. This analysis provides an alternative way of looking at the problem in question, through propagation of photons, as a physically more appealing approach, in Feynman’s spirit, than by matching plane waves at boundaries as we often do. It also shows how a propagator may be derived, in more complex situations with specific boundary conditions, than just simply in infinite extended spaces. Finally, it is hoped that this work will be stimulating and of interest to practitioners with different emphases on EM wave propagation.

Instanton and noninstanton tunneling in periodically perturbed barriers: Semiclassical and quantum interpretations

In multidimensional barrier tunneling, there exist two different types of tunneling mechanisms, instanton-type tunneling and noninstanton tunneling. In this paper we investigate transitions between the two tunneling mechanisms from the semiclassical and quantum viewpoints taking two simple models: a periodically perturbed Eckart barrier for the semiclassical analysis and a periodically perturbed rectangular barrier for the quantum analysis. As a result, similar transitions are observed with change of the perturbation frequency ω for both systems, and we obtain a comprehensive scenario from both semiclassical and quantum viewpoints for them. In the middle range of ω, in which the plateau spectrum is observed, noninstanton tunneling dominates the tunneling process, and the tunneling amplitude takes the maximum value. Noninstanton tunneling explained by stable-unstable manifold guided tunneling (SUMGT) from the semiclassical viewpoint is interpreted as multiphoton-assisted tunneling from the quantum viewpoint. However, in the limit ω→0, instanton-type tunneling takes the place of noninstanton tunneling, and the tunneling amplitude converges on a constant value depending on the perturbation strength. The spectrum localized around the input energy is observed, and there is a scaling law with respect to the width of the spectrum envelope, i.e., the width ∝ℏω. In the limit ω→∞, the tunneling amplitude converges on that of the unperturbed system, i.e., the instanton of the unperturbed system.

Assessment of In-Flight Water Droplet Evaporation: The Contribution of Numerical Approximation Methods

The design of an irrigation system must limit the depletion of water due to the evaporation process, for social, environmental and economic reasons. In order to assess the evaporation it is important to fully understand how water, in the form of droplets, behaves during its flight. The state of the art of literature offers at the moment two main ways: the first one consists in adopting a classical viewpoint, using simplifying hypothesis to solve numerical approximation methods [1-12]. The second possibility is to adopt a quantum viewpoint, treating the water droplet as a quantum object [13]. By using this last method one can obtain a description as much as possible complete and doubtless the challenges associated with the quantum mechanics applied to droplets problems will continue to inspire progress in the years to come, but at the present time the fact that is impossible to find analytical solutions for quantum equations makes sometimes preferable to achieve the purpose through numerical approximations. In particular, the numerical approximation can be implemented via suitable codes and in this way a further step in literature has been taken using a Computational Fluid Dynamics (CFD) implementation [1416].

Non-instanton tunneling: Semiclassical and quantum interpretations

Tunneling essentially different from instanton-type tunneling, say noninstanton tunneling, is studied from both semiclassical and quantum viewpoints. Taking a periodically perturbed rounded-off step potential for which the instanton-type tunneling is substantially prohibited, we analyze change of the tunneling probability with change of the perturbation frequency based on the stable-unstable manifold-guided tunneling (SUMGT) theory, which we have recently introduced. In the large and small limits of the frequency, the tunneling rate rapidly decays, but it is markedly enhanced in an intermediate range. We will also make a quantum interpretation of the noninstanton tunneling by using an exactly solvable model--a periodically perturbed right-angled step potential. Analysis with this model shows that SUMGT is considered as a sort of photoassisted tunneling through a large energy gap induced with absorbing a huge number quanta, which is completely different from the instanton-type tunneling. Both approaches from the semiclassical and quantum viewpoints complement each other to cause a better understanding of noninstanton tunneling.

QUANTUM DYNAMICS OF COUPLED BOSONIC WELLS WITHIN THE BOSE–HUBBARD PICTURE

We relate the quantum dynamics of the Bose–Hubbard model (BHM) to the semiclassical nonlinear equations that describe an array of interacting Bose condensates by implementing a standard variational procedure based on the coherent state method. We investigate the dynamics of the two-site BHM from the purely quantum viewpoint by recasting first the model within a spin picture and using then the related dynamical algebra. The latter allows us to study thoroughly the energy spectrum structure and to interpret quantally the classical symmetries of the two-site dynamics. The energy spectrum is also evaluated through various approximations relying on the coherent state approach.

Čerenkov radiation in discontinuous media: a quantum view-point

The photon propagator in the Čerenkov radiation off a charged particle moving in a dielectric slab immersed within another dielectric medium is derived. From the vacuum-to-vacuum transition amplitude, an explicit expression is obtained for the photon number density of given frequency of photons radiated per unit path length of the particle. In particular, it is shown that near threshold, the density behaves like sin θ c rather than of the well known behavior of sin 2 θ c for uniformly extended media and may be of interest experimentally, where θ c is the Čerenkov-cone half-angle. The derived expression is applied to the visible region. The analysis is given from a field-theory view-point.