We derive an analytical expression for the propagation factor(known as M2-factor) of electromagnetic concentric rings Schell-model(EM CRSM) beams in non-Kolmogorov turbulence by utilizing the extended Huygens–Fresnel diffraction integral formula and the second-order moments of the Wigner distribution function(WDF). Our results show that the EM CRSM beam has advantage over the scalar CRSM beam for reducing the turbulence-induced degradation under suitable conditions. The EM CRSM beam with multi-rings far-fields in free space is less affected by the turbulence than the one with dark-hollow far-fields or the electromagnetic Gaussian Schell-model(EGSM) beam. The dependence of the M2-factor on the beam parameters and the turbulence are investigated in detail.
A generalized type of spiral Bessel beam has been demonstrated by using a spatially displaced helical axicon (HA).The topological charge of the spiraling Bessel beams is determined by the order of the input Laguerre-Gaussian (LG) beam and the topological charge of the HA.The obtained spiraling Bessel beams have an LG type of modulation along their propagation direction and exhibit annihilation-reconstruction properties.Theoretical analysis is presented,including that of the stability,propagation distance,topological charge,and spiraling dynamic characteristics.The mathematical and numerical results show that the propagation distance and helical revolution of the spiraling Bessel beams can be controlled through choosing appropriate radius of the HA.
This paper discusses some statistical properties of the superposition of two coherent states with a vacuum state,such as sub-Poissonian photon statistics and negativity of the Wigner function.Phase probability distribution and phase variance are calculated.Special cases of the constructed superposition states are presented.The results show that depending on the vacuum state coefficient γ and the coherent state coefficient α,it can generate a variety of nonclassical states.
By means of concurrence, we investigate the dynamics of entanglement between two initially separate atoms in succession passing through a cavity and their interaction with a Fock state field. We then analyze the effects of the atomic coherence, photon number, and atomic motion on the time evolution of atom-atom entanglement. The results show that there can be entanglement between two separate atoms, and that the threshold time for the creation of the entanglement is controllable by the photon number, atomic motion, and field-mode structure.
It has been recently demonstrated that negative-index dispersion and mode degeneracy can be achieved by manipulating a spoof-insulator-spoof(SIS) waveguide. In this paper, we propose a new SIS waveguide, which is composed of two spoof surface plasmon polaritons(SSPPs) waveguides drilled with periodic rhomboidal grooves. Both the symmetric and asymmetric cases are investigated. Our simulation results show that the asymmetric SIS waveguides are more significant.By tailoring the tilt of the rhomboidal grooves, the negative-index dispersion can be achieved and the microwave band gap(MBG) can be effectively modulated. At a critical tilt, there appears an accidental mode degeneracy at the edge of the first Brillouin zone. The excitation and propagation of the two coupled modes sustained by the asymmetric SIS waveguides are also demonstrated.
We investigate the dynamics of strongly localized solitons trapped in remote troughs of radially periodic lattices with Kerr-type self-focusing nonlinearity.The rotary motion of solitons is found to be more stable for larger nonlinear wavenumbers,lower rotating velocity,and shorter radius of the trapping troughs. When the lattice is shrunk or expanded upon propagation,the solitons can be trapped in the original trough and move outward or inward,with their rotating linear velocity inversely proportional to the radius of the trapping troughs.
According to the electromagnetic field distributions, there exist two kinds of coupled spoof surface plasmon polaritons(SSPPs), the symmetric and anti-symmetric modes, in the three-dimensional(3D) subwavelength spoof–insulator–spoof(SIS) waveguide. We study the dispersion and excitation of the two kinds of coupled SSPPs supported by the 3D SIS waveguide. The evolution of the dispersion with the thickness and gap width of the waveguide is numerically investigated,and we give a theoretical analysis according to the coupling mechanism. Specially, based on the coupling mechanism,we design a zipper structure, through which the excitation and propagation of the anti-symmetric coupled modes can be realized effectively.
The effects of decoherence on elliptical states which concern the quantum superposition of N coherent states on an ellipse in the α plane are studied.The characteristic decoherence times are determined.The evolutions of the Wigner functions associated with these states are investigated theoretically and the losses of nonclassicality as a result of decoherence are discussed.The result shows that the decoherence of elliptical states is slower than circular states relying on the number of coherent states and the amplitude,and the constructed states have a higher resilience to losses.
We investigate the prominent impacts of coupling strengths on the evolution of entanglement and quantum discord for a three-qubit system coupled to an XY spin-chain environment. In the case of a pure W state, more robust, even larger nonzero quantum correlations can be obtained by tailoring the coupling strengths between the qubits and the environment.For a mixed state consisting of the GHZ and W states, the dynamics of entanglement and quantum discord can characterize the critical point of quantum phase transition. Remarkably, a large nonzero quantum discord is generally retained, while the nonzero entanglement can only be obtained as the system-environment coupling satisfies certain conditions. We also find that the impact of each qubit's coupling strength on the quantum correlation dynamics strongly depends on the variation schemes of the system-environment couplings.
