通讯机构：
[Deng, Xiaohui] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
关键词：
Thermodynamic properties;Quasiharmonic approximation;Lattice dynamics;Density functional theory
摘要：
The finite-temperature density functional theory and the quasiharmonic approximation are adopted to investigate thermodynamics properties of hexagonal osmium. By varying lattice volume, the anharmonic effect is part considered in present work. Phonon frequencies calculations are performed from density functional perturbation theory (DFPT). By fitting the total free energy (including both electronic and vibrational parts) to equation of states at different temperatures, some classical thermodynamic quantities and their pressure and temperature dependences are investigated systematically. The results are in good agreement with the available experimental and theoretical data.Research Highlights► The finite-temperature DFT and QHA were adopted. ► Thermodynamic properties were investigated systematically. ► CV reaches a constant (∼3 R) with T approaching to the ΘD. ► CP shows an approximate linear behavior beyond the experimental ΘD. ► The temperature dependence on γ is small.
摘要：
Based on the full two-dimensional characteristics of the quasi-phase-matched fan-out periodically poled crystal, a scalable and engineerable scheme for ultrabroadband optical parametric chirped-pulse amplification is proposed, which can significantly broaden the gain bandwidth by the spatial separation of different frequency components of the signal pulse and manipulation of the distribution of the pump beam along the fan-out direction of the crystal. The theoretical analysis shows that the signal pulse can be amplified with minimal spectrum narrowing, and the initial spectrum can be broadened considerably if needed. Based on this scheme, using a fan-out periodically poled 5% mol MgO-doped congruent lithium niobate with a configuration of 5×0.5×5 mm3 and two pump beams, the 3.3−μm middle-infrared ultrabroadband optical parametric chirped-pulse amplifier is designed. The numerical computation results confirm that the −3 dB gain bandwidth of this amplifier exceeds 320 nm and can be further broadened.
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
关键词：
Quantum secret;Hierarchical splitting;Photonic qubit;Cluster states
摘要：
We propose a scheme for hierarchical quantum information splitting with the recently realized six-photon cluster state (Lu et al. in Nat. Phys. 3:91, 2007), where a Boss distributes a quantum secret (quantum state) to five distant agents who are divided into two grades. Two agents are in the upper grade and three agents are in the lower grade. An agent of the upper grade only needs the collaboration of two of the other four agents for getting the secret, while an agent of the lower grade needs the collaboration of all the other four agents. In other words, the agents of two grades have different authorities to recover Boss’s secret. KeywordsQuantum secret-Hierarchical splitting-Photonic qubit-Cluster states
摘要：
We propose and implement a quasi-discrete Hankel transform algorithm based on Dini series expansion (DQDHT)in this paper. By making use of the property that the zero-order Bessel function derivative J'_0(0)=0,the DQDHT can be used to calculate the values on the symmetry axis directly. In addition,except for the truncated treatment of the input function,no other approximation is made,thus the DQDHT satisfies the discrete Parseval theorem for energy conservation,implying that it has a high numerical accuracy. Further,we have performed several numerical tests. The test results show that the DQDHT has a very high numerical accuracy and keeps energy conservation even after thousands of times of repeating the transform either in a spatial domain or in a frequency domain. Finally,as an example,we have applied the DQDHT to the nonlinear propagation of a Gaussian beam through a Kerr medium system with cylindrical symmetry. The calculated results are found to be in excellent agreement with those based on the conventional 2D-FFT algorithm,while the simulation based on the proposed DQDHT takes much less computing time.
