We implement optical pumping to prepare cold atoms in our prototype of the ST Rb space cold atom clock, which operates in the one-way mode. Several modifications are made on our previous physical and optical system. T...We implement optical pumping to prepare cold atoms in our prototype of the ST Rb space cold atom clock, which operates in the one-way mode. Several modifications are made on our previous physical and optical system. The effective atomic signal in the top detection zone is increased to 2.5 times with 87% pumping efficiency. The temperature of the cold atom cloud is increased by 1.4 μK. We study the dependences of the effective signal gain and pumping efficiency on the pumping laser intensity and detuning. The effects of σ transition are discussed. This technique may be used in the future space cold atom clocks.展开更多
Electromagnetically induced transparency （EIT） is investigated in a system of cold, interacting cesium Rydberg atoms. The utilized cesium levels 6S1/2, 6P3/2 and nD5/2 constitute a cascade three-level system, in whi...Electromagnetically induced transparency （EIT） is investigated in a system of cold, interacting cesium Rydberg atoms. The utilized cesium levels 6S1/2, 6P3/2 and nD5/2 constitute a cascade three-level system, in which a coupling laser drives the Rydberg transition, and a probe laser detects the EIT signal on the 6S1/2 to 6/23/2 transition. Rydberg EIT spectra are found to depend on the strong interaction between the Rydberg atoms. Diminished EIT transparency is obtained when the Rabi frequency of the probe laser is increased, whereas the corresponding linewidth remains unchanged. To model the system with a three-level Linclblad equation, we introduce a Rydberg-level dephasing rate γ3 = κ×（P33/Ωp）^2, with a value κ that depends on the ground-state atom density and the Rydberg level, The simulation results are largely consistent with the measurements. The experiments, in which the principal quantum number is varied between 30 and 43, demonstrate that the EIT reduction observed at large Ωp is due to the strong interactions between the Rydberg atoms.展开更多
Evolution of a non-neutral cold electron-positron plasma slab is investigated. Initially the slab consists of a quasineutral plasma core bounded on both sides by layers containing only positrons （or electrons）. Resu...Evolution of a non-neutral cold electron-positron plasma slab is investigated. Initially the slab consists of a quasineutral plasma core bounded on both sides by layers containing only positrons （or electrons）. Results from a nonperturbative, or mathematically exact, analysis of the governing fluid conservation equations and the Poisson equation show that despite their equal mass and charge magnitude, the electron and positron fronts can expand separately as well as a single fluid, and that nonlinear surface oscillations can be excited on the expansion fronts.展开更多
We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the elect...We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.展开更多
Since the end of 2009, north China has been repeatedly struck by arctic-like blasts of cold weather. As temperatures have plummeted to historic lows, they have inflicted considerable suffering as well.
A bone-chilling winter throughout the Northern Hemisphere does not refute global warming As Arctic winds blow over North America, Europe and East Asia, I many parts of north China have
本文的标题中的Questioned系动词question的被动形式。若标题不作省略,其完整表达应当是:Advice to Drink Liquids During a Cold Is Questioned。汉语的相应表达应该是:患感冒期间应该多喝水的建议受到质疑。是啊,感冒了?多喝水!这确...本文的标题中的Questioned系动词question的被动形式。若标题不作省略,其完整表达应当是:Advice to Drink Liquids During a Cold Is Questioned。汉语的相应表达应该是:患感冒期间应该多喝水的建议受到质疑。是啊,感冒了?多喝水!这确实是一个universally recommending advice,读者朋友,读了此文,你可要多个心眼哟!展开更多
基金Supported by the Fund from the Ministry of Science and Technology of China under Grant No 2013YQ09094304the Youth Innovation Promotion Association of Chinese Academy of Sciences
文摘We implement optical pumping to prepare cold atoms in our prototype of the ST Rb space cold atom clock, which operates in the one-way mode. Several modifications are made on our previous physical and optical system. The effective atomic signal in the top detection zone is increased to 2.5 times with 87% pumping efficiency. The temperature of the cold atom cloud is increased by 1.4 μK. We study the dependences of the effective signal gain and pumping efficiency on the pumping laser intensity and detuning. The effects of σ transition are discussed. This technique may be used in the future space cold atom clocks.
基金Supported by the National Basic Research Program of China under Grant No 2012CB921603Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China under Grant No IRT13076+2 种基金the State Key Program of the National Natural Science of China under Grant No 11434007the National Natural Science of China under Grant Nos 11274209,61475090,60378039 and 61378013Shanxi Scholarship Council of China(2014-009)
文摘Electromagnetically induced transparency （EIT） is investigated in a system of cold, interacting cesium Rydberg atoms. The utilized cesium levels 6S1/2, 6P3/2 and nD5/2 constitute a cascade three-level system, in which a coupling laser drives the Rydberg transition, and a probe laser detects the EIT signal on the 6S1/2 to 6/23/2 transition. Rydberg EIT spectra are found to depend on the strong interaction between the Rydberg atoms. Diminished EIT transparency is obtained when the Rabi frequency of the probe laser is increased, whereas the corresponding linewidth remains unchanged. To model the system with a three-level Linclblad equation, we introduce a Rydberg-level dephasing rate γ3 = κ×（P33/Ωp）^2, with a value κ that depends on the ground-state atom density and the Rydberg level, The simulation results are largely consistent with the measurements. The experiments, in which the principal quantum number is varied between 30 and 43, demonstrate that the EIT reduction observed at large Ωp is due to the strong interactions between the Rydberg atoms.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11247007,11374262 and 11475147the Natural Science Foundation of Zhejiang Province under Grant No LY15A050001the Fundamental Research Funds for Central Universities,and the Open Fund of the State Key Laboratory of High Field Laser Physics at SIOM
文摘Evolution of a non-neutral cold electron-positron plasma slab is investigated. Initially the slab consists of a quasineutral plasma core bounded on both sides by layers containing only positrons （or electrons）. Results from a nonperturbative, or mathematically exact, analysis of the governing fluid conservation equations and the Poisson equation show that despite their equal mass and charge magnitude, the electron and positron fronts can expand separately as well as a single fluid, and that nonlinear surface oscillations can be excited on the expansion fronts.
基金Supported by the Yarmouk Universitythe KUSTAR–KAIST Institution Fund
文摘We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.
文摘Since the end of 2009, north China has been repeatedly struck by arctic-like blasts of cold weather. As temperatures have plummeted to historic lows, they have inflicted considerable suffering as well.
文摘A bone-chilling winter throughout the Northern Hemisphere does not refute global warming As Arctic winds blow over North America, Europe and East Asia, I many parts of north China have
文摘本文的标题中的Questioned系动词question的被动形式。若标题不作省略,其完整表达应当是:Advice to Drink Liquids During a Cold Is Questioned。汉语的相应表达应该是:患感冒期间应该多喝水的建议受到质疑。是啊,感冒了?多喝水!这确实是一个universally recommending advice,读者朋友,读了此文,你可要多个心眼哟!
