Implementation of Full Spin-State Interferometer

Matter-wave interferometers with spin quantum states are attractive in quantum manipulation and precision measurements. Here, five spatial interference patterns corresponding to the full spin states are observed in each run of the experiment, by the combination of the Majorana transition according to the exponential modulation of the magnetic field pulse decline curve and radio frequency coupling among multiple magnetic sub-states.Compared to the realization of two Majorana transitions, the interference fringe for the magnetic field insensitive state also has a higher contrast. After spatially overlapping the full magnetic sub-state interference patterns dozens of times in consecutive experimental measurements, clear fringes are still observed, indicating the great stability of the relative phases of different components. This indicates the potential to achieve an interferometer with multiple spin clocks.     

强激光束在等离子体通道中传输的变分法研究

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Observation of Two-Dimensional Mott Insulator and π-Superfluid Quantum Phase Transition in Shaking Optical Lattice

The Mott insulator and superfluid phase transition is one of the most prominent phenomena in ultracold atoms. We report the observation of a novel 2D quantum phase transition between the Mott insulator and πsuperfluid in a shaking optical lattice. In the deep optical lattice regime, the lowest S band can be tuned to Mott phase, while the higher Px,y bands are itinerant for having larger bandwidth. Through a shaking technique coupling the s-orbital to px,y-orbital states, we experimentally observ...     

波谱学及其在我国三十年

波谱学是研究辐射和物质共振相互作用的科学．通过观测和研究这种相互作用的各种现象及其机理,人们可以得到物质的内部结构及其运动规律的知识．波谱学所涉及的辐射主要处在射频、微波、毫米波直至远红外波段,大体上是频率在１０１３Ｈｚ以下（波长在３０μｍ以上）的区域;它所处理的主要的是能级之间的受激跃迁．波谱学可以看成是光谱学的延长和发展,历史上,它由物理学的三个领域汇聚融合而来,这就是：远红外,毫米波,?...     

玻色-爱因斯坦凝聚实验中的蒸发冷却过程研究

玻色-爱因斯坦凝聚(BEC)和在此基础上实验的原子激射器(Atom Laser)是本世纪末物理学研究最重要的成果,为此该领域的科学家获得了2001年诺贝尔物理奖.     

无反转放大效应(AWI)对光速减慢与负群速传播的影响

由于光子作为信息的载体有着天然的优越性,例如,传播速度快,信息量大等.所以各国科学家都在不断地寻找各种方法去操控光子.其中电磁感应透明(Electromagnetically Induced Transparency, EIT),电磁感应吸收(Electromagnetically Induced absorption, EIA)和无反转放大效应(Amplification Without Inversion, AWI)作为控制光子的手段一直受到人们的关注.电磁感应透明现象(EIT)可以实现共振光无吸收传播的同时伴随有大的群速度色散效应.我们实现了无缓冲气体的铯泡(Cs)中的光脉冲群速度的减慢,通过在EIT的原子系统上加入非相干泵浦来产生AWI效应,我们发现光脉冲在其中的传播速度随着泵浦光强的增加而明显减小,延迟时间增加一倍,光脉冲的群速度相当于c/40000.此外,我们还利用电磁感应吸收现象(EIA)产生的大的负群速度色散效应,我们观察到了在无缓冲气体的铯泡(Cs)中,光脉冲的负群速度传播的现象.通过EIA原子系统中非相干泵浦光的加入,AWI 效应使得超光速现象变得更加明显,光脉冲的负群速度变得更大.最大的光脉冲超前时间可以达到0.9 μs,相当于光脉冲的群速度为-c/40000.     

偏磁场对双表面微磁阱的影响

将纳米技术和冷原子物理相结合,可以形成表面微磁阱,研究微阱中冷原子以及玻色-爱因斯坦凝聚体的物理性质有着潜在的应用前景.     

Observation of F = 2 Spinor Bose-Einstein Condensation in a Magnetic Field

Multiple-component Bose-Einstein condensation has been observed in a magnetic field generated by a controllable magnetic quadrupole-Ioffe-configuration trap. Different distributions of atoms in spinor Bose Einstein condensates are created by changing the time difference of switching-off current in quadrupole-Ioffe-configuration coils and bias coils of the magnetic trap. A simple analysis is carried out to explain some phenomena of the experiment.     

A Quasi-1D Potential for Bose Gas Phase Fluctuations

An elongated trap potential for cold atoms is designed based on a quadrupole-Ioffe configuration.Phase fluctuations in a Bose-Einstein condensate(BEC),which is confined by the trap,are studied.We simulate the atom density distribution induced by fluctuation after time of flight from this elongated trap potential and study the temperature measurement method related to the distribution.Furthermore,taking advantage of the tight confinement and radio frequency dressing technique,we propose a double well potential for splitting BECs.Our results are helpful for improving understanding of low-dimensional quantum gases and provide important guidance for atomic interferometry.