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In this paper, an explicit finite-difference scheme is developed in staggered grids for solving the Maxwell's equations in time domain. We are aimed to preserve the discrete zero-divergence condition in the electrical and magnetic fields and conserve the inherent laws in non-dispersive simple media all the time using the explicit second-order accurate symplectic partitioned Runge-Kutta temporal scheme for the time derivative terms. The spatial derivative terms in the semi-discretized Faraday's and Ampère's equations are then approximated to get an accurate numerical dispersion relation equation that governs the numerical angular frequency and the wavenumbers for the Maxwell's equations defined in two space dimensions. To achieve the goal of getting the best dispersive characteristics in the chosen grid stencil, a fourth-order accurate space centered scheme with the ability of minimizing the difference between the exact and numerical dispersion relation equations is proposed. Our emphasis is placed on the accurate modeling of EM waves in the dispersive media of the Debye, Lorentz and Drude types. Through the computational exercises, the proposed dual-preserving Maxwell's equation solver is computationally demonstrated to be efficient for use to predict the long-term accurate wave solutions in a medium belonging either to a frequency independent or dependent type. [ABSTRACT FROM AUTHOR]

The Experimental Advanced Superconducting Tokamak (EAST) has a major radius of R0 = 1.75 m and a midplane halfwidth of 0.5 m. It has been operated with a toroidal magnetic field B0 = 2 T and Ip ⩽ 500 kA. The evolution of the plasma equilibrium is analysed between discharges by Equilibrium Fitting Code (EFIT). Limiter, single-null and double-null diverted configurations have been produced. A plasma elongation in the range 1.3 ⩽ ? ⩽ 1.9 and a triangularity in the range 0.1 ⩽ δ ⩽ 0.55 have been sustained. The operation space of elongated discharges is also presented based on the EAST database. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the geometric phase of a composite system which is composed of two spin- $\frac{1}{2}$ particles driven by a time-varying magnetic field. Firstly, we consider the special case that only one subsystem driven by time-varying magnetic field. Using the quantum jump approach, we calculate the geometric phase associated with the adiabatic evolution of the system subjected to decoherence. The results show that the lowest order corrections to the phase in the no-jump trajectory is only quadratic in decoherence coefficient. Then, both subsystem driven by time-varying magnetic field is considered, we show that the geometric phase is related to the exchange-interaction coefficient and polar angle of the magnetic field. [ABSTRACT FROM AUTHOR]

We theoretically study the features of the spontaneous emission spectra in a coherently driven cold four-level atomic system with a cyclic configuration. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, and spectral-line suppression can be realized in our system. Interestingly enough, the spectral-line enhancement and suppression can be controlled just by appropriately modulating the phase, the frequency, and the intensity of an external coherent magnetic field, respectively. This investigation may find applications in high-precision spectroscopy. [ABSTRACT FROM AUTHOR]

We study coherent laser-induced optical behaviors in weak twin-light propagation through strained diamond nitrogen-vacancy (NV) centers via switching on and off an external magnetic field. By numerically solving the coupled Bloch-Maxwell equations for NV center and field simultaneously in space and time, we address dynamic control of pulse propagation and magneto-optic dual switching in such a laser-driven NV center system. The proposed scheme may have applications in the design of magneto-optic switching and magneto-optic storage devices. [ABSTRACT FROM AUTHOR]