We investigate transverse electromagnetic waves propagating in a plasma influenced by the gravitational field of the Reissner–Nordström black hole. Applying 3+1 spacetime split we reformulate the relativistic two-fluid equations to take account of gravitational effects due to the event horizon and describe the set of simultaneous linear equations for the perturbations. Using a local approximation we investigate the one-dimensional radial propagation of Alfvén and high frequency electromagnetic waves. We derive the dispersion relation for these waves and solve it for the wave number k numerically. 相似文献
In this paper we introduce a toy model for understanding the growth of structures and the two point correlation functions in the cotext of the Quasi-Steady State Cosmology (QSSC). The paper first describes the essential features of the QSSC and then addresses the problem of structure formation. 相似文献
Strong two‐photon absorption (TPA) in monolayer MoS2 is demonstrated in contrast to saturable absorption (SA) in multilayer MoS2 under the excitation of femtosecond laser pulses in the near‐infrared region. MoS2 in the forms of monolayer single crystal and multilayer triangular islands are grown on either quartz or SiO2/Si by employing the seeding method through chemical vapor deposition. The nonlinear transmission measurements reveal that monolayer MoS2 possesses a nonsaturation TPA coefficient as high as ∼(7.62 ±0.15) ×103 cm/GW, larger than that of conventional semiconductors by a factor of 103. As a result of TPA, two‐photon pumped frequency upconverted luminescence is observed directly in the monolayer MoS2. For the multilayer MoS2, the SA response is demonstrated with the ratio of the excited‐state absorption cross section to ground‐state cross section of ∼0.18. In addition, the laser damage threshold of the monolayer MoS2 is ∼97 GW/cm2, larger than that of the multilayer MoS2 of ∼78 GW/cm2.
We propose a scheme to realize W states for N-atoms trapped in two distant cavities connected by an optical fiber. In the scheme, the cavity modes and fiber mode are not excited during the process. The quantum information is encoded in two degenerate ground states, so the atom's spontaneous emission can be omitted approximately. Moreover, the operation speed increases with the number of the atoms without a limitation and thus the scheme is extremely robust against decoherence. 相似文献