Entropy and Entanglement of the Electromagnetically Induced Transparency System

We study the entropy and the entanglement of an electromagnetically induced transparency system. The quantumentanglement between the atom and the two quantized laser fields is discussed by using quantum reduced entropyand that between the two quantized laser fields by using quantum relative entropy. We also examine whetherinfluences of EIT on entropy and quantum entanglement of the system considered occur or not. Our resultsshow that the minimum value of the atomic reduced entropy may be regarded as an entropy criterion on theelectromagnetically induced transparency occurring.     

Four-Wave Mixing Scheme in a Four-Level Ladder-Type Atomic System Based on Electromagnetically Induced Transparency

A nonlinear optical four-wave mixing scheme is presented and analysed for the generation of coherent light ina nearly four-level ladder-type atomic system in the context of electromagnetically induced transparency (EIT).We find that EIT can suppress nonlinear photon absorption and the peak of the generated mixing field is locatedat the centre of the transparency window where the loss is minimal, though there is a dip in the centre. Such anonlinear optical process can also be used for generating coherent short-wavelength radiation.     

Transparency induced by two-photon interference in a beam splitter

We propose a special two-photon state which is completely transparent in a 50/50 beam splitter. This effect is caused by the destructive two-photon interference and shows the signature of photon entanglement. We find that the symmetry of the two-photon spectrum plays the key role for the properties of two-photon interference.     

Design of Second-Order Nonlinear Optical Molecules Exhibiting Improved Nonlinearity-Transparency Trade-off and Large Nonlinearity

The nonlinear second-order optical susceptibilities(β) of a series of multi-branched molecules with triphenylbenezene as π center have been calculated by means of a combination of intermediate neglect of differential overlap Hamiltonian with the configuration interaction(INDO/SDCI) method combined with sum-over-states expression(SOS) .the results show that the β values are increased by replacing benzene rings with thiophene rings in the branches,as well as by increasing the donating and accepting strength of the three terminal substituents.The properies of the intermolecular charge transfer were studied through the calculation of charge changes between the ground and the main excited states and the frontier orbitals of these molecules.The results also indicate that these molecules investigated here possess improved transparency-nonlinearity properties.     

NO2-N2O4平衡体系定量化探究

勒夏特列原理一直被描述为定性理论。以NO2-N2O4平衡体系为例,初步探讨了化学平衡体系中吸光物质的浓度与压强、温度之间的函数关系。     

声波团聚技术发展现状及在火灾消烟应用前景*

声波团聚技术在细颗粒物排放控制领域具有很好的应用前景,最近衍生发展为一种全新的火灾烟雾控制手段。该文对声波团聚技术发展现状进行全面总结,介绍近年的实验和理论研究进展。随后,阐述了声波团聚消烟的基本原理,并以火灾烟雾中占比较大的电缆燃烧烟雾为实验对象,发现声波团聚技术在一分钟后就实现对电缆燃烧烟雾的完全消除,即存在突出团聚效果。该结果验证了该技术在火灾烟雾控制领域的可行性。最后,依托我国城市发展现状,探讨了声波团聚技术在火灾消烟的发展前景。