Enhancement of Quantum Entanglement in Cavity–Magnon systems

In article number 2400221, Rong-Can Yang, Hong-Yu Liu, and co-workers focus on the enhancement of quantum entanglement and quantum steering in cavity–magnon hybrid systems using quantum coherent feedback (QCFB) control loops, as shown in the cover image. In the scheme, SQUID is applied to realize Josephson parametric amplification, driving the 3D microwave cavity with two-photon field. Moreover, quantum correlation of the two magnon modes is indirectly established through the magnetic dipole interaction, and the enhancement is implemented effectively with QCFB.

Negative-Mass Black Holes under Antichronous Transformations

Black hole's gravitational singularities are solved by interior negative energies and masses through time transformations of relativistic quantum mechanics and antichronous transformations of the full Lorentz group, which, if taking place at event horizons, respect Einstein's equivalence principle. For further details, see article number 2400139 by Manuel Uruena Palomo.

Lorentz invariance belongs to the fundamental symmetries of nature. It is argued that a non-vanishing nonmetricity of a metric-affine geometry of spacetime heralds the violation of the Lorentz symmetry.

The field of femtosecond laser direct writing PeQDs in transparent amorphous glass media has become a prominent research domain, offering innovative viewpoints and opportunities for the progress and application of PeQDs@glass. This review summarizes the latest advancements in laser-induced PeQDs within the glass, highlighting its luminescent properties and wide-ranging applications.

1D models with topological non-trivial band structures are a simple and effective way to study novel and exciting concepts in topological photonics. Here, the propagation of light-matter quasi-particles, so-called exciton-polaritons, is studied in topological waveguide arrays. To precisely control the propagation, a novel resonant excitation in transmission geometry is included. The results highlight a new platform for the study of quantum fluids of light and non-linear optical propagation effects in coupled semiconductor waveguides.

A non-singular black hole solution is presented which violates energy conditions only at its interior by postulating a shift to negative energies and antigravitational negative masses at the event horizon, respecting Einstein's equivalence principle and avoiding the runaway motion paradox. This shift is the unitary parity-time transformation of relativistic quantum mechanics and the proper antichronous transformation of the full Lorentz group.

Enhancement of quantum correlation for two magnon modes in a cavity-magnon hybrid system by using a nonlinear flux-driven JPA and a feedback loop is proposed. Numerical simulations demonstrate that the introduction of feedback loops make quantum correlation effectively enhanced and robust against thermal noise, thus providing better prospects for experimental development.

Phase plot corresponding to the viscous f (Q) model with red dot represents the unstable critical point, whereas the green dot denotes the stable one.

This work examines energy localization in non-Hermitian systems, emphasizing the role of topological defects in spherical models. It explores mode alterations in non-Hermitian Su-Schrieffer-Heeger chains using Maximum Skin Corner Weight metric and introduces a spherical model for studying non-Hermitian skin effect. Circuit experiment validations support the findings, indicating the spherical topological circuit plays a role in investigating non-Hermitian phenomena.

This work captures the novel idea that if any security protocol is running based on the maximal quantum violation of network inequality for the Bilocal network scenario and star network scenario, then the middle party has the strength to activate his local classical model without informing anyone and still can get the maximal violation just by asking one end party not to choose the measurement inputs randomly. It has been demonstrated how effective it can be to lose some amount of measurement independence in the quantum network scenario when simulating the network nonlocal correlation classically.

Geometry for the generation of a pseudorandom Fraunhofer diffraction pattern from a 2D Gauss grating. Planewaves impinge from the left on the Gauss grating in the (x,y)-plane giving rise to the diffraction pattern shown on the right. The Gauss grating is based on a 2D nonperiodic lattice.

The formalism of generalized quantum histories, allowing a symmetrical treatment of space and time correlations, is briefly reviewed, and used to characterize spatial and temporal entanglement. An operative protocol is presented, to map a history state into the ket of a static composite system. We show, by examples, how the Leggett-Garg and the temporal CHSH inequalities can be violated in this approach.

This work studies localization-delocalization quantum phase transitions (QPTs) in a cavity optomechanical system for the first time. It is found that that QPTs between the localization phase and delocalization phase of phonons can happen through tuning the photon-assisted phonon tunneling interaction. It is demonstrated that the photon-assisted QPTs are the second order QPTs. It is indicated that the ground state of the localization phase is a separable squeezed state while the ground state of the de localization phase is an entangled state.

This article investigates the stability of anisotropic spheres in extended symmetric teleparallel gravity using the model with Tolman–Kuchowicz spacetime. By analyzing the conditions for matching interior and exterior geometries and examining physical properties using observational data from compact objects, this article demonstrates that the viability and stability of the model are being investigated.