Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature

This study extends the investigation of quantum dissipative effects of a cosmological scalar field by taking into account cosmic expansion and contraction.Cheung,Drewes,Kang,and Kim calculated the effective action and quantum dissipative effects of a cosmological scalar field in a recent work,where analytical expressions for the effective potential and damping coefficient were presented using a simple scalar model with quartic interactions,and the work was conducted using Minkowski-space propagators in loop diagrams.In this work,we incorporate the Hubble expansion and contraction of the cosmic background and focus on the thermal dynamics of a scalar field in a regime where the effective potential changes slowly.Given that the Hubble parameter,H,attains a small but non-zero value,we carry out calculations to the first order in H.If we set H=0,all results match those in flat spacetime.Interestingly,we must integrate over the resonances,which in turn leads to an amplification of the effects of a non-zero H.This is an intriguing phenomenon,which cannot be uncovered in flat spacetime.The implications on particle creations in the early universe will be studied in a forthcoming study.     

Electronic Transitions in Different Redox States of Trinuclear 5,6,11,12,17,18-Hexaazatrinaphthylene-Bridged Titanium Complexes: Spectroelectrochemistry and Quantum Chemistry

Multinuclear transition metal complexes bridged by ligands with extended π-electronic systems show a variety of complex electronic transitions and electron transfer reactions. While a systematic understanding of the photochemistry and electrochemistry has been attained for binuclear complexes, much less is known about trinuclear complexes such as hexaphenyl-5,6,11,12,17,18-hexaazatrinaphthylene-tristitanocene [(Cp₂Ti)₃HATN(Ph)₆]. The voltammogram of [(Cp₂Ti)₃HATN(Ph)₆] shows six oxidation and three reduction waves. Solution spectra of [(Cp₂Ti)₃HATN(Ph)₆] and of the electrochemically formed oxidation products show electronic transitions in the UV, visible and the NIR ranges. Density functional theory (DFT) and linear response time-dependent DFT show that the three formally titanium(II) centers transfer an electron to the HATN ligand in the ground state. The optically excited transitions occur exclusively between ligand-centered orbitals. The charged titanium centers only provide an electrostatic frame to the extended π-electronic system. Complete active self-consistent field (CASSCF) calculation on a structurally simplified model compound, which considers the multi-reference character imposed by the three titanium centers, can provide an interpretation of the experimentally observed temperature-dependent magnetic behavior of the different redox states of the title compound in full consistency with the interpretation of the electronic spectra.     

Complementarity between micro-micro and micro-macro entanglement in a Bose–Einstein condensate with two Rydberg impurities

We theoretically study complementarity between micro-micro and micro-macro entanglement in a Bose–Einstein condensate with two Rydberg impurities. We investigate quantum dynamics of micro-micro and micro-macro entanglement in the micro-macro system. It is found that strong micro-macro entanglement between Rydberg impurities and the BEC can be generated by the use of initial micro-micro entanglement between two Rydberg impurities, which acts as the seed entanglement to create micro-macro entanglement. We demonstrate a curious complementarity relation between micro-micro and micro-macro entanglement, and find that the complementarity property can be sustained to some extent even though in the presence of the BEC decoherence.     

Analysis,design and simulation of MIM plasmonic filters with different geometries for technical parameters improvement

In this paper, four optical filter topologies based on metal–insulator–metal waveguides are proposed and the designed structures are investigated numerically using finite-difference timedomain method. Triangular-shaped adjunctions have been added to the filter structures to improve their transmission spectrum. These improved structures consist of air as the insulator and silver as the metal. The relative permittivity of metal has been described via the Drude,Drude–Lorentz, and Palik models. The first filter's transmission spectrum shows an acceptable transmittance. In the second optimized filter, the transmission spectrum has been improved. The transmittance spectrum can be tuned through adjusting the edge of the triangle in these four optimized filters. As a result, the bandwidths of resonance spectra can be adjusted. The theory of such tapered structures will be investigated by the tapered transmission line and will be solved with the transfer matrix method. This method shows a better performance and higher transmission efficiency in comparison with the basic structures. On the other hand, the final filter has been chosen as the best one because of its hexagonal resonator. The main reason for having a better result is due to a longer interaction length in comparison with the circular resonator. This in turn creates much better energy coupling and results in higher transmission.     

EAST装置上W波段多道极向相关反射仪的研制

在EAST装置上安装了X模极化W波段多道相关反射仪，用于测量等离子体芯部密度涨落。该诊断利用低损耗(<3dB)多工器将4个不同频率(79.2GHz，85.2GHz，91.8GHz和96GHz)的微波耦合在一起，通过同一个天线发射。反射波由两个极向分离(~5cm)的天线接收，通过下变频技术实现外差测量。通过对两个极向天线接收的信号进行相关分析，获得芯部湍流垂直速度。对2018年低约束模式(L模)放电进行分析发现，在电子回旋共振加热(ECRH)等离子体中，芯部湍流垂直速度在电子逆磁漂移方向。而在注入同向中性束(co-NBI)后，芯部湍流垂直速度变为离子逆磁漂移方向。     

Eu^3+激活氟氧硼酸锗酸盐闪烁玻璃的发光性能

采用传统高温熔融法合成了玻璃组成为B2O3-GeO2-15GdF3-(40-x)Gd2O3-xEu2O3(0≤x≤10)的Eu^3+激活氟氧硼酸锗酸盐闪烁玻璃。在硼锗酸盐玻璃基质中,Gd2O3和GdF3稀土试剂的总含量高达55%,从而确保其密度高于6.4 g/cm^3。闪烁玻璃的光学性能通过光学透过光谱、光致发光光谱、X射线激发发射(XEL)光谱和荧光衰减曲线来表征。玻璃中Gd^3+→Eu^3+离子的能量传递通过激发光谱、发射光谱和Gd^3+-Eu^3+离子间距得到证明,同时也确定了在紫外线和X射线激发下Eu^3+激活氟氧硼酸锗酸盐闪烁玻璃的最佳浓度。Judd-Ofelt理论分析了玻璃中Eu―O键的共价性随Eu^3+掺杂浓度增加而显著增强。Eu^3+激活氟氧硼酸锗酸盐闪烁玻璃在80~470 K温度范围内荧光衰减曲线和发射光谱的温度依赖关系最终证实了其具有较好的发光稳定性。