共查询到17条相似文献,搜索用时 206 毫秒
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玻色-爱因斯坦凝聚在中国科学院上海光机所实现 总被引:4,自引:0,他引:4
文章报道了在稀薄87Rb原子气体中观测到的玻色 -爱因斯坦凝聚 (BEC)现象 .在四极矩和Ioffe组合磁阱 (QUIC)中装载了 1× 10 8个原子 ,经过 19s蒸发冷却达到了相变条件 .在高原子密度的情况下 ,文章作者观察到了BEC对探测光的衍射光环 .这时降低磁阱势垒和绝热的放开冷原子样品 ,我们拍摄到冷原子和BEC的吸收像 .根据数据拟合满足双高斯分布 ,表明发生了BEC相变 .相变温度约 2 15nK ,凝聚的原子数约为 5× 10 4 . 相似文献
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采用二维磁光阱产生了-个快速~(87)Rb原子流,并在高真空的三维磁光阱中实现了~(87)Rb原子的快速俘获,进一步采用射频蒸发冷却技术实现了原子云的预冷却,然后将原子转移到远失谐的光学偶极阱中蒸发得到了玻色-爱因斯坦凝聚体.实验上可以在25 s内完成三维磁光阱的装载(约1.0×10~(10)个~(87)Rb原子),然后经过16 s的冷却过程最终在光学偶极阱中获得5.0×10~5个原子的玻色-爱因斯坦凝聚体.实验重点研究了二维磁光阱的优化设计和采用蓝失谐大功率光束对四极磁阱零点的堵塞,抑制四极磁阱中原子的马约拉纳损耗,更加有效地对原子云进行预冷却. 相似文献
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本文在39K-87Rb混合气体的|F=1,mF=-1>态上获得了双组分玻色-爱因斯坦凝聚体(Bose-Einstein condensates,BECs)。由于39K原子气体的背景散射长度是负值,必须利用磁场调节Feshbach共振技术来操控其散射长度,从而实现39K原子气体的有效蒸发冷却。在0~200 G磁场强度范围内,我们分别测量了39K-87Rb混合气体的同核和异核Feshbach共振,并确定了它们在|1,-1>态中的散射长度与磁场的对应关系。通过优化39K-87Rb混合气体中原子种内和种间的相互作用,进一步比较了在不同磁场区域39K-87Rb混合气体的协同蒸发冷却效率。最后,实验上制备出39K-87Rb混合气体|1,-1>态的双组分BECs,同时为接下来进一步研究量子液滴等相互作用体系提供了理想的平台... 相似文献
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提出了一种采用两套超大红失谐消逝波干涉和一束蓝失谐消逝波光场来实现原子二维表面微光阱阵列和原子有效强度梯度冷却的新方案,得到了二维表面微光阱阵列的光强分布和光学势分布.研究发现,二维表面微光阱阵列中微光阱的光学势能够有效地囚禁从标准磁光阱中释放的冷原子,并且被囚禁的冷原子能在蓝失谐消逝波光场的作用下产生有效的强度梯度Sisyphus冷却,对87Rb原子而言,原子温度能被冷却到2.56μK.该方案在冷原子物理、原子光学和量子光学领域中有着广阔的应用前景.
关键词:
消逝波干涉
微光阱阵列
原子囚禁
强度梯度冷却 相似文献
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对40K-87Rb原子冷却的半导体激光系统提出了一种实验方案,并进行了初步实验.采用三台外腔光栅反馈半导体激光器(ECDL)、四台注入锁定从激光器和一台半导体激光放大器组成激光系统.三台ECDL通过声光调制器产生四束光,分别作为40K和87Rb原子的冷却光和再抽运光,四束不同频率成分的激光分别注入锁定四台从激光器,然后Rb 冷却光、K冷却光和K再抽运光再同时注入半导体激光放大器进行放大.该装置可同时产生冷却40K和87Rb原子的冷却光和再抽运光,结构紧凑、工作稳定.
关键词:
简并费米气体
激光器系统
外腔光栅反馈半导体激光器
半导体激光放大器 相似文献
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An antiproton cloud cooled at 4.2 K in a Penning trap can be further cooled by adiabatic reduction of the trap magnetic and
electric fields. It will be shown that the temperature can be reduced by two orders of magnitude. This cooling method may
be useful to obtain ultra-low energy antiprotons for the measurement of their gravitational properties and the production
of ultra-low energy antihydrogen atoms. 相似文献
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McKeever J Buck JR Boozer AD Kuzmich A Nägerl HC Stamper-Kurn DM Kimble HJ 《Physical review letters》2003,90(13):133602
Single cesium atoms are cooled and trapped inside a small optical cavity by way of a novel far-off-resonance dipole-force trap, with observed lifetimes of 2-3 s. Trapped atoms are observed continuously via transmission of a strongly coupled probe beam, with individual events lasting approximately 1 s. The loss of successive atoms from the trap N>/=3-->2-->1-->0 is thereby monitored in real time. Trapping, cooling, and interactions with strong coupling are enabled by the trap potential, for which the center-of-mass motion is only weakly dependent on the atom's internal state. 相似文献
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C. Klempt T. Henninger O. Topic J. Will St. Falke W. Ertmer J. Arlt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):121-126
We report on the simultaneous transport of mixed quantum
degenerate gases of bosonic 87Rb and fermionic 40
K in a harmonic potential. The samples are transported over a
distance of
to the geometric center of a
Ioffe-Pritchard type magnetic trap. This transport mechanism was
implemented by modification of the QUIC trap and is free of losses
and heating. It significantly extends the capabilities of this trap
design. We demonstrate a launching mechanism for quantum degenerate
samples and show that highly homogeneous magnetic fields can be
created in the center of the QUIC trap. The transport mechanism may
also be cascaded to cover even larger distances for interferometric
experiments with quantum degenerate samples. 相似文献
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The research platform for Bose-Einstein condensate in 87Rb atomic gas, which is composed of a double MOT configuration and a QUIC trap, was reported. The properties of the condensate
were measured both in time-of-flight and in tight confinement by the absorption imaging method. The measurements agreed with
the criterions of Bose-Einstein condensation phase transition. About 2×105 atoms were pure condensed.
Supported by the National Natural Science Foundation of China (Grant No. 10334050) and the National Basic Research Program
of China (Grant Nos. 2001CB309307 and 2006CB921202) 相似文献
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Binnewies T Wilpers G Sterr U Riehle F Helmcke J Mehlstäubler TE Rasel EM Ertmer W 《Physical review letters》2001,87(12):123002
Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of (40)Ca atoms has been cooled and trapped to a temperature as low as 6 microK by operating a magnetooptical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method, more than 10% of precooled atoms from a standard magnetooptical trap have been transferred to the ultracold trap. Monte Carlo simulations of the cooling process are in good agreement with the experiments. 相似文献
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This paper presents an experimental demonstration of light-induced
evaporative cooling in a magneto-optical trap. An additional laser
is used to interact with atoms at the edge of the atomic cloud in
the trap. These atoms get an additional force and evaporated away
from the trap by both the magnetic field and laser fields. The
remaining atoms have lower kinetic energy and thus are cooled. It
reports the measurements on the temperature and atomic number after
the evaporative cooling with different parameters including the
distance between the laser and the centre of the atomic cloud, the
detuning, the intensity. The results show that the light-induced
evaporative cooling is a way to generate an ultra-cold atom source. 相似文献
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Quantum Degenerate Fermi--Bose Mixtures of 40K and 87Rb Atoms in a Quadrupole-Ioffe Configuration Trap 总被引:2,自引:0,他引:2
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We report on the attainment of quantum degeneracy of 40^K by means of efficient thermal collisions with the evaporatively cooled 87^Rb atoms. In a quadrupole-Ioffe configuration trap, potassium atoms axe cooled to 0.5 times the Fermi temperature. We obtain up to 7.59 × 10^5 degenerate fermions 40^K. 相似文献