Near-$$AdS_2$$ perturbations and the connection with near-extreme Reissner–Nordstrom

The geometry very near the horizon of a near-extreme Reissner–Nordstrom black hole is described by the direct product of a near-$$AdS_2$$AdS2 spacetime with a two-sphere. While near-$$AdS_2$$AdS2 is locally diffeomorphic to $$AdS_2$$AdS2 the two connect differently with the asymptotically flat part of the geometry of (near-)extreme Reissner–Nordstrom. In previous work, we solved analytically the coupled gravitational and electromagnetic perturbation equations of $$AdS_2\times S^2$$AdS2×S2 and the associated connection problem with extreme Reissner–Nordstrom. In this paper, we give the solution for perturbations of near-$$AdS_2\times S^2$$AdS2×S2 and make the connection with near-extreme Reissner–Nordstrom. Our results here may also be thought of as computing the classical scattering matrix for gravitational and electromagnetic waves which probe the region very near the horizon of a highly charged spherically symmetric black hole.

Dynamical evolution of electromagnetic perturbation in the background of a scalar hairy black hole in Horndeski theory

We have investigated dynamical evolution of electromagnetic perturbation in a scalar hairy black hole spacetime, which belongs to solutions in Horndeski theory with a logarithmic cubic term. Our results show that the parameter [Formula: see text] affects the existence of event horizon and modifies the asymptotical structure of spacetime at spatial infinity, which imprints on the quasinormal frequency of electromagnetic perturbation. Moreover, we find that the late-time tail of electromagnetic perturbation in this background depends also on the parameter [Formula: see text] due to the existence of solid angle deficit. These imply that the spacetime properties arising from the logarithmic cubic term in the action play important roles in the dynamical evolutions of the electromagnetic perturbation in the background of a scalar hairy black hole.

A Quantum-Based Microwave Magnetic Field Sensor

In this paper, a quantum-based method for measuring the microwave magnetic field in free space is presented by exploring atomic Rabi resonance in the clock transition of 133Cs. A compact cesium glass cell serving as the microwave magnetic field sensing head was used to measure the spatial distribution of microwave radiation from an open-ended waveguide antenna. The measured microwave magnetic field was not restricted by other microwave devices. The longitudinal distribution of the magnetic field was measured. The experimental results measured by the sensor were in agreement with the simulation. In addition, a slightly electromagnetic perturbation caused by the glass cell was investigated through simulation calculations.

Design of Cylindrical Metamaterial Invisible Cloak with Non-Singular Electromagnetic Tensors

Based on line transformation, cylindrical metamaterial invisible cloak with non-singular electromagnetic tensors is designed. The results of simulation software based on finite element methods (FEM) show that the singularity in the electromagnetic tensors of the cloak has been eliminated, comparing with the cylindrical cloak with ideal tensors. From the simulation results, although there is electromagnetic perturbation in the free-space of the solution region, this cloak exhibits nice electromagnetic invisible performance. The bending wave front is clearly seen when the incoming wave transmits into the cloak region. Because of the non-singular electromagnetic tensors, the designed cloak may have more engineering application than the cloak with idea tensors.