Hard Photons from a Non-Equilibrated Quark-Gluon Plasma with Finite Baryon Density at a Two-Loop Level

We study hard photon production from a two-loop level （bremsstrahlung and annihilation with scattering） in a chemically equilibrating quark-gluon plasma at finite baryon density based on Jüttner distribution of partons of the system. We find that the photon yield from the two-loop level increases obviously with the increasing initial quark chemical potential.

Daytime Radiative Cooling:Artificial and Bioinspired Strategies

Traditional cooling systems have been posing a significant challenge to the global energy crisis and climate change due to the high energy consumption of the cooling process.In recent years,the emerging daytime radiative cooling provides a promising solution to address the bottleneck of traditional cooling technology by passively dissipating heat radiation to outer space without any energy consumption through the atmospheric transparency window(8~13μm).Whereas its stringent optical criteria require sophisticated and high cost fabrication producers,which hinders the applicability of radiative cooling technology.Many efforts have been devoted to develop high-efficiency and low-cost daytime radiative cooling technologies for practical application,including the nanophotonics based artificial strategy and bioinspired strategy.In order to systematically summarize the development and latest advance of daytime radiative cooling to help developing the most promising approach,here in this paper we will review and compare the two typical strategies on exploring the prospect approach for applicable radiative cooling technology.We will firstly sketch the fundamental of radiative cooling and summarize the common methods for construction radiative cooling devices.Then we will put an emphasis on the summarization and comparison of the two strategies for designing the radiative cooling device,and outlook the prospect and extending application of the daytime radiative cooling technology.

Elliptic flow of direct photons in Au+Au collisions at 200 GeV

The rapidity dependence of the elliptic flow of direct photons in Au＋Au collisions at√ s NN = 200 GeV are predicted,based on a three-dimensional ideal hydrodynamic description of the hot and dense matter.The rapidity dependence of the elliptic flow v 2 （y） of direct photons （mainly thermal photons） is very sensitive to the initial energy density distribution along longitudinal direction,which provides a useful tool to extract the realistic initial condition from measurements.

Preparation and heat insulating capacity of Sm2Zr2O7-SiC composites based on photon thermal transport

A series of Sm2Zr2O7-SiC composites doped with different volume fraction and particle size of SiC were prepared by hot pressing at 1300°C.The phase of the composites prepared is P-Sm2Zr2O7 and C-SiC,and no other diffraction peaks exist,which indicates that Sm2Zr2O7 has great chemical compatibility with SiC.The thermal conductivity and phonon thermal conductivity of the Sm2Zr2O7-SiC composites are measured by the laser pulse method.The photon thermal conductivity of the composites is obtained by subtracting the phonon thermal conductivity from the total thermal conductivity.The results show that the photon thermal conductivity of Sm2Zr2O7-SiC composites is lower than that of pure Sm2Zr2O7.The photon thermal conductivity of Sm2Zr2O7-SiC composites decreases first and then increases with the increase of SiC particle size.Sm2Zr2O7-(5 vol%,10µm)SiC composite has the lowest photon thermal conductivity.

Reduced thermal sensitivity of hybrid air-core photonic band-gap fiber ring resonator

A novel hybrid air-core photonic band-gap fiber(PBF) ring resonator with twin 90° polarization-axis rotated splices is proposed and demonstrated. Frist, we measure the temperature dependent birefringence coefficient of air-core PBF and Panda fiber. Experimental results show that the relative temperature dependent birefringence coefficient of air-core PBF is 1.42×10^(-8)/℃, which is typically ~16 times less than that of Panda fiber. Then, we extract the geometry profile of air-core PBF from scanning electron microscope(SEM) images. Numerical modal is built to distinguish the fast axis and slow axis in the fiber. By precisely setting the length difference in air-core PBF and Panda fiber between two 90° polarization-axis rotated splicing points, the hybrid air-core PBF ring resonator is constructed, and the finesse of the resonator is 8.4. Environmental birefringence variation induced by temperature change can be well compensated, and experimental results show an 18-fold reduction in thermal sensitivity, compared with resonator with twin 0° polarization-axis rotated splices.

Light control with Weyl semimetals

Weyl semimetals are topological materials whose electron quasiparticles obey the Weyl equation.They possess many unusual properties that may lead to new applications.This is a tutorial review of the optical properties and applications of Weyl semimetals.We review the basic concepts and optical responses of Weyl semimetals,and survey their applications in optics and thermal photonics.We hope this pedagogical text will motivate further research on this emerging topic.