We create a Bose-Einstein condensate （BEC） of 87Rb atoms by runaway evaporative cooling in an optical trap. Two crossed infrared laser beams with a wavelength of 1064 nm are used to form an optical dipole trap. After precooling the atom samples in a quadrupole-Ioffe configuration （QUIC） trap under 1.5 #K by radio-frequency （RF） evaporative cooling, the samples are transferred into the center of the glass cell, then loaded into the optical dipole trap with 800 ms. The pure condensate with up to 1.5× 10^5 atoms is obtained over 1.17 s by lowering the power of the trap beams.
正交模分裂(或真空R ab i分裂)是原子与光学腔构成的复合系统实现强相互作用的一个典型现象。本文理论研究了三能级原子介质与腔构成的复合系统,利用线性色散理论将腔内三能级原子自感应透明(E IT)介质的吸收和色散引入光学腔透射公式,非常直观清晰得到腔透射谱的三个分裂峰,它是由腔内E IT介质的吸收和色散特性使一个共振腔模分裂为三个腔模。该方法可以推广到腔内含有任意色散和吸收的介质。
We study ^（87）Rb Bose-Einstein condensation（BEC） loading into the pulse of the one-dimensional（1D） optical lattice experimentally.The lattice is turned on abruptly,held constant for a variable time,and then turned off abruptly.The measurement of the depth of the optical lattice is obtained by Kapitza-Dirac scattering.The temporal matter-wave-dispersion Talbot effect with ^（87）Rb BEC is observed by applying a pair of pulsed standing waves（as pulsed phase gratings） with the separation of a variable delay.
We report the experimental achievement of ^（87）Rb Bose-Einstein condensation in a magnetic trap with microwave and radio frequency（RF） induced evaporation.Evaporative cooling is realized by using 6.8 GHz microwave radiation driving the ^（87）Rb atoms to transit from the ground-state hyperfine state ｜F=2,m_F= 2〉to ｜F=l,m_F=1〉.Compared with RF-induced evaporation,^（87）Rb atoms are hardly to achieve pure condensate by microwave evaporation cooling due to the effect of atoms in the ｜F=1,m_F=1〉state being pumped back into the trapping ｜F=2,m_F=1〉state.
