Annalen der Physik最新文献

The Lorentz–Drude model for electric dipoles is a classical framework widely used in the study of dipole dynamics and light-matter interactions. This article focuses on the behavior of Lorentz–Drude dipoles when their radiative rate dominates their energy loss. It is asserted that dipole radiation losses do not count toward phenomenological dipole losses if the driving field is interpreted as the total field at the dipole. In particular, if the dipole does not contain non-radiative losses, then the Lorentz–Drude damping term should be removed. This is verified by self-consistent implementations of point dipoles in finite-difference time-domain simulations, which also provide a method to directly compute the transport properties of light when dipoles are present.

The optimal generation of entangled states is of significance to information processing and state engineering. Here, an efficient scheme is proposed for creating entangled states between two superconducting qubits in a circuit quantum electrodynamics (QED). The two qubits that resonantly interact with a common cavity mode of transmission-line resonator (TLR) can be effectively coupled by the data bus of the microwave resonator. By the invariant-based shortcuts to adiabaticity (STA), two types of maximally entangled states can be controllably induced only by adjusting the Rabi drivings. Based on the resonant drivings with constant rates, the shortcut strategy is capable of implementing faster operations when compared with the dispersive approach. The fidelities are highly robust against the decoherence effects and the instabilities of Rabi rates. Thus the proposal could offer a potential route toward the entanglement generations in an optimized manner.

The realization of the distant entanglement, especially in the macroscopic domain, is crucial for advancing quantum technology. Here, a scheme is presented to enhance the stationary entanglement between two distant rotating mirrors in a cascaded Laguerre–Gaussian cavity optorotational system by adjusting the phase difference between two counterpropagating driving lasers. These findings indicate that the entanglement between two rotating mirrors can be significantly enhanced by increasing the phase difference between two input lasers. Additionally, the maximum entanglement between two rotating mirrors depends on the effective cavity detuning. Furthermore, increasing the phase difference between two input lasers can enhance the robustness of the entanglement between two mechanical modes against the thermal noise of the environment. Moreover, the phonon numbers of the two rotating mirrors can be reduced by controlling the phase difference of input lasers. And the ground-state cooling of the two rotating mirrors can be achieved at two different phase differences of input lasers, whose difference is about $�\pi$.

In this study, the geodesic motion of both massless and massive test particles is examined around a spherically symmetric Finslerian Bardeen-like black hole (BH) that incorporates the effects of a quintessence field (QF) and a global monopole (GM). It is analyzed that how the presence of the QF and GM modifies the non-Riemannian spacetime geometry and significantly alters the dynamics of test particles compared to those in standard BH models, including numerical solutions for photon deflection trajectories. In addition, spin-0 scalar field perturbations is investigated by deriving a wave-like equation in the background of this modified BH geometry. It is studied that how the Finslerian structure, along with the QF and GM, influences the effective scalar perturbation potential. Using this potential, the spectrum of quasinormal modes (QNMs) are computed and the dynamical stability of the BH under scalar perturbations is assessed. Furthermore, the deflection of light rays is analyzed in the vicinity of the BH in the weak-field limit. These results show how the inclusion of Finslerian geometry, the QF, and the GM modifies the deflection angle compared to that in the classical Bardeen BH model formulated in Riemannian geometry. Overall, these findings highlight the significant role that non-Riemannian geometry, coupled with quintessential fields and global monopoles, plays in shaping the macroscopic and observational features of BHs.

Here, an enhanced sonic black hole (ESBH) structure is proposed to achieve efficient low-frequency broadband sound absorption. The ESBH design features a conical cavity formed by a bilaterally tapered power-law profile and incorporates porous material filling to enhance acoustic energy dissipation, particularly in the low-frequency range where conventional sonic black hole structures are limited by weak air damping. The theoretical foundation is established using a transfer matrix method that accounts for the modified wave number induced by the porous medium. The model is validated numerically and employed to investigate the influence of key structural parameters on the absorption coefficient. To further enhance performance, a hybrid optimization strategy is utilized that combines a backpropagation neural network with an improved grasshopper optimization algorithm. The optimized structure exhibits superior sound absorption and transmission loss characteristics while minimizing overall volume. Experimental verification demonstrates that the proposed ESBH structure outperforms traditional designs in terms of low-frequency acoustic performance, indicating strong potential for practical noise reduction applications.

Cognition, information processing in form of inference, communication, and memorization, is the central activity of any intelligence. Its physical realization in a brain, computer, or in any other intelligent system requires resources like time, energy, memory, bandwidth, money, and others. Due to limited resources, many real world intelligent systems perform only imperfect cognition. To understand the trade-off between accuracy and resource investments in existing systems, e.g., in biology, as well as for the resource-aware optimal design of information processing systems, like computer algorithms and artificial neural networks, a quantification of information obtained in an imperfect cognitive operation is desirable. To this end, the concept of the achieved information gain (AIG) of a belief update is proposed, which is given by the amount of information obtained by updating from the initial state of knowledge to the ideal state, minus the amount that a change from the imperfect to the ideal state would yield. AIG has many desirable properties for quantifying imperfect cognition. The ratio of achieved to ideally obtainable information measures cognitive fidelity and that of AIG to the necessary cognitive effort measures cognitive efficiency. This work provides an axiomatic derivation of AIG, relates it to other information measures, illustrates its application to common scenarios of posterior inaccuracies, and discusses the implication of cognitive efficiency for sustainable resource allocation in computational inference.