Annalen der Physik最新文献

The construction of a transformation image is pivotal to the transformation design method for steering waves around an object. Constructing the conformal images of an electron, however, remains a challenge, primarily due to the complexities involved in realizing the spin structure within the image space. This study proposes a novel solution in this regard of the electron's spin structure on a $��2�d�$ surface, leveraging on the interactions between the electron and a vector potential. By introducing a scalar potential to facilitate the generation of a conformal metric structure and differential operator in the Dirac equation, it is demonstrated that the conformal image of the electron can indeed be constructed within an appropriate electromagnetic field. Furthermore, an equivalence between the geometric effect of a conformal deformation on the electron and the action of an electromagnetic force is established. Electromagnetic fields are used to generate form-invariant conformal images of the electron within a plane and on a sphere. These examples help showcase the effectiveness of the currently presented method in realizing the conformal images of the electron in various settings.

The problem of the structure and physical properties of electrically charged static spherically symmetric solutions of the Einstein-Maxwell system of equations is revisited, where the matter model is a polytropic gas. A relativistic polytrope equation of state (EOS) is considered and the electric charge density is assumed to be proportional to the rest mass density. Families of solutions corresponding to various sets of parameters are constructed and analyzed their stability and compliance with the causality requirement, emphasizing the possibility of obtaining black hole mimickers. Concretely, this study wants to test how much electric charge a given object can hold and how compact it can be. It is concluded that there is a microscopic bound on the charge density to rest mass density ratio coincident with the macroscopic bound regarding the extremal Reissner-Nordström (ERN) black hole. The macroscopic charge to mass ratio for the object can exceed the corresponding microscopic ratio if the object is non-extremal. Crucially, the only way to construct a black hole mimicker is by taking a subtle limit in which an electrically counterpoised dust (ECD) solution is attained.

The interconversion of different types of entangled states not only can realize the information transmission but also play a significant role in quantum information technologies, including increasing scalability and computational power, and reducing error rates. Here, two protocols for achieving a complete interconversion between W state and Knill–Laflamme–Milburn state assisted by the quantum dot (QD)-cavity systems and common quantum control gates are proposed. In particular, the protocols employ a heralded approach strategically designed to predict potential failures and facilitate seamless interaction between the QD-cavity system and photons with the help of a single photon detectors, enhancing experimental accessibility. Through extensive analyzes and evaluations of two protocols, the proposed two protocols achieve remarkable utilization rates of photons (i.e., unit in principle) and achieve near-unit fidelities and high efficiencies in principle.

In this work, a power law $��f�\left(�Q�\right)�$ model is explored, specifically, $��f��\left(�Q�\right)��=�\alpha �Q^n�$, along with viscous matter fluid having transport coefficient $��\zeta �=�{\zeta }_0�\sqrt{�\Omega �}�+�{\zeta }_1�\Omega �H�$. The corresponding analytical solution is derived and then confronted with recent cosmic data. The Markov Chain Monte Carlo (MCMC) sampling technique is utilized to estimate the mean value of arbitrary parameters, by incorporating Cosmic Chronometers and recently published Pantheon+Analysis samples. In addition, some cosmological parameters are reconstructed by resampling the chains obtained by emcee, incorporating 6000 samples. It is found that the matter-energy density depicts the expected positive behavior, whereas the effective pressure indicates the negative behavior that is leading the accelerating expansion, which is further predicted in the effective EoS parameter. Further, the asymptotic nature of the assumed model is investigated by invoking phase-space analysis. It is concluded that the assumed viscous $��f�\left(�Q�\right)�$ model successfully predicts an evolution of the universe from decelerated epoch to stable accelerated de-Sitter epoch.

From a dynamical systems point of view, a trivalent spin network model in Loop Quantum Gravity is considered, which presents self-organized criticality (SOC), arising from a spin propagation dynamics. A partition function is obtained for the domains of stability connecting gauge non-invariant avalanches, leading to an entropy formula for the asymptotic SOC state. The microscopic origin of this SOC entropy is therefore given by the excitation-relaxation spin dynamics in the avalanche cycle. The puncturing of trivalent spin networks (TSN) edges participating in the avalanche are counted in terms of an ensemble perimeter over the implicit avalanches. By identifying this perimeter with that of an isolated $��(�2�+�1�)�$-D black hole horizon, it is conjectured that the SOC entropy reduces to the Bekenstein-Hawking perimeter-entropy law for the Bañados, Teitelboim, and Zanelli (BTZ) black hole, by an appropriate adjustment of a potential function based on the thermodynamical formalism of Sinai, Ruelle, and Bowen.

It is crucial to design quantum circuits as small as possible and as shallow as possible for quantum information processing tasks. Quantum circuits are designed with simplified gate-count, cost, and depth for implementing quantum teleportation among various entangled channels. Here, the gate-count/cost/depth of the Greenberger-Horne-Zeilinger-based quantum teleportation is reduced from 10/6/8 to 9/4/6, the two-qubit-cluster-based quantum teleportation is reduced from 9/4/5 to 6/3/5, the three-qubit-cluster-based quantum teleportation is reduced from 12/6/7 to 8/4/5, the Brown-based quantum teleportation is reduced from 25/15/17 to 18/8/7, the Borras-based quantum teleportation is reduced from 36/25/20 to 15/8/11, and the entanglement-swapping-based quantum teleportation is reduced from 13/8/8 to 10/5/5. Note that, no feed-forward recover operation is required in the simplified schemes. Moreover, the experimentally demonstrations on IBM quantum computer indicate that the simplified and compressed schemes can be realized with good fidelity.

Photon Blockades in an Optomechanical Cavity

In article number 2300465, Le-Man Kuang and co-workers study the photon blockades in an optomechanical cavity with a BoseEinstein condensate. By tuning the interatomic scattering strength, a switch between single-photon blockade and photon-induced tunneling can be realized, and the enhancement of single-photon blockade can be achieved in both interatomic repulsion and attraction conditions. Moreover, the system can exhibit stronger single-photon blockade under the same optomechanical coupling than a conventional optomechanical system.

Wavelength-Scale Singlet Achromatic Microlens

A traditional lens is usually bulky and heavy for it is a combination of several designed lenses to correct the chromatic aberration. A metalens is based on the achromatic phase response of the nanostructures, which can exhibit an excellent achromatic performance in a wavelength-level thickness, however, relies on nano-fabrication. In article number 2300543, Yang Bai, Jingbo Sun, and co-workers propose a general design principle to develop a microlens with high-index materials with both the achromatic performance and a small thickness.

In this work, first of all, a number of hidden aspects of the concept of particle oscillations are analyzed. The key element of this concept, which does not comply with the principle of least action, is the notion of a mixture of particles, introduced by Gell–Mann, and Pais for neutral $�K$-mesons. It is proven that the law of conservation of energy-momentum in the processes of electron neutrino production does not allow solving the problem of solar neutrinos based on the assumption of Gribov and Pontecorvo about their oscillations. It is established that the consequences of Wolfenstein's equation contradict the results of the SNO and Super-Kamiokande collaborations and that the assertion by Mikheev and Smirnov on the conversion of solar neutrinos is erroneous. Another part of the work is devoted to a logically clear solution to this problem based on the hypothesis of the existence of a new interaction, the carrier of which is a massless pseudoscalar boson, which has a Yukawa coupling with electron neutrinos and nucleons. At each act of interaction of an electron neutrino with the nucleons of the Sun, caused by such interaction, the handedness of the neutrino changes from left to right and vice versa, and also the neutrino energy decreases. The hypothesis provides good agreement between the theoretical and experimental values of the rates of all five observed processes with solar neutrinos. This serves as a significant criterion for both the confidence of such a solution to the problem of solar neutrinos and the confidence of the existence of a new interaction.