共查询到19条相似文献,搜索用时 140 毫秒
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从平均场理论出发,针对有限温度下的玻色-爱因斯坦凝聚态的特点,从正则系综的自由能函数变化的角度,推演并得出了临界温度移动的表达式。为同类实验提供了理论依据. 相似文献
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玻色-爱因斯坦凝聚态的奇观GaryTaubes1995年6月5日美国科罗拉多(Colorado)大学和在波尔德(Boulder)的美国国家标准和技术研究所(NIST)的几位物理学家研制出一种新的物质状态,玻色-爱因斯坦凝聚态(以下称BE凝聚).他们是... 相似文献
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介绍了磁光捕获冷原子和玻色-爱因斯坦凝聚的物理特性及相关发展和研究,阐述了如何通过实验得到磁光捕获和玻色-爱因斯坦凝聚,并介绍了相关仪器,详细说明了测量其温度及捕获的原子数量的方法.同时还介绍了插入光和磁场上移等获得玻色-爱因斯坦凝聚的方法及红失谐和蓝失谐光如何捕获冷原子的研究.最后介绍了作者所做的研究:冷原子的快速压缩法和玻色-爱因斯坦凝聚的绝热捷径. 相似文献
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本文介绍了北京大学建立的玻色-爱因斯坦凝聚实验平台,实现了玻色-爱因斯坦凝聚(图1),获得了原子数为五十万个,温度为50纳开尔文的玻色凝聚体。在此基础上我们精密测量了玻色-爱因斯坦凝聚的相变温度,还利用玻色-爱因斯坦凝聚实验平台通过马越让那跃迁获得了可控的多量子态玻色爱因斯坦凝聚体。并利用四种方法获得了原子激光(图2),其中有三种方法是国际上第一次使用。另外,我们提出了将玻色一爱因斯坦凝聚转入Magic光晶格阱,实现精度优于10^-17的新型原子钟的设想。 相似文献
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对最近提出的具有纠缠序参量的玻色-爱因斯坦凝聚体作通俗简要的介绍.在这个凝聚体中,不同种原子间形成自旋纠缠的原子对,而系统就在这个纠缠对上发生玻色-爱因斯坦凝聚. 相似文献
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山西大学量子光学与光量子器件国家重点实验室张靖教授研究小组于7月7日成功实现了铷原子的玻色-爱因斯坦凝聚(BEC).实验结果显示,冷原子云在温度降低到约为500nK时开始发生相变,经过进一步蒸发冷却,最终得到了约为6×104个原子的纯净BEC.目前该小组正将铷原子和费米原子钾40同时装入磁阱中,蒸发冷却铷原子来协同冷却钾原子,最终同时实现玻色气体玻色-爱因斯坦凝聚和费米气体量子简并. 相似文献
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利用格子液体方法对V型三能级原子玻色-爱因斯坦凝聚体与双模压缩相干态光场相互作用系统的哈密顿量进行分析,发现文献中对原子间相互作用部分的处理有不合理之处,从而对该哈密顿量作出了改进并研究了V型三能级原子玻色-爱因斯坦凝聚体与双模压缩相干态光场相互作用系统中原子激光的两个正交分量的压缩性质.研究表明:V型三能级原子玻色-爱因斯坦凝聚体中光场-原子相互作用强度对原子激光的两正交分量的涨落有明显的影响.
关键词:
玻色-爱因斯坦凝聚
V型三能级原子
压缩相干态
压缩原子激光 相似文献
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We study the quantum dynamics of an impurity-doped Bose–Einstein condensate (BEC) system. We show how to generate the macroscopic quantum superposition states (MQSSs) of the BEC by the use of projective measurements on impurity atoms. It is found that the nonclassicality of MQSSs can be manipulated by changing the number of the impurities and their interaction with the BEC. It is shown that the BEC matter-wave field exhibits a collapse and revival phenomenon which reveals the quantum nature of the BEC matter-wave field. We investigate the micro-macro entanglement between the impurities and the BEC, and find enhancement of the micro-macro entanglement induced by the initial quantum coherence of the impurity atoms. 相似文献
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A simple second quantization model is used to describe a two-mode Bose-Einstein condensate (BEC), which can be written in terms of the generators of a SU(2) algebra with three parameters. We study the behavior of the entanglement entropy and localization of the system in the parameter space of the model. The phase transitions in the parameter space are determined by means of the coherent state formalism and the catastrophe theory, which besides let us get the best variational state that reproduces the ground state energy. This semiclassical method let us organize the energy spectrum in regions where there are crossings and anticrossings. The ground state of the two-mode BEC, depending on the values of the interaction strengths, is dominated by a single Dicke state, a spin collective coherent state, or a superposition of two spin collective coherent states. The entanglement entropy is determined for two recently proposed partitions of the two-mode BEC that are called separation by boxes and separation by modes of the atoms. The entanglement entropy in the boxes partition is strongly correlated to the properties of localization in phase space of the model, which is given by the evaluation of the second moment of the Husimi function. To compare the fitness of the trial wavefunction its overlap with the exact quantum solution is evaluated. The entanglement entropy for both partitions, the overlap and localization properties of the system get singular values along the separatrix of the two-mode BEC, which indicates the phase transitions which remain in the thermodynamical limit, in the parameter space. 相似文献
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N. Bilas N. Pavloff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):387-397
We study the elementary excitations of a transversely confined
Bose-Einstein condensate in presence of a weak axial random potential. We
determine the localization length (i) in the hydrodynamical low energy regime,
for a domain of linear densities ranging from the Tonks-Girardeau to the
transverse Thomas-Fermi regime, in the case of a white noise potential and
(ii) for all the range of energies, in the “one-dimensional mean field
regime”, in the case where the randomness is induced by a series of randomly
placed point-like impurities. We discuss our results in view of recent
experiments in elongated BEC systems. 相似文献
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研究了单模光腔中两组分玻色-爱因斯坦凝聚的基态性质和相关的量子相变.通过利用自旋相干态变换将等效赝自旋哈密顿算符对角化并求得基态能量泛函.基态能量泛函对其经典场变量进行变分并取极小值,得到光子数解和相边界曲线.通过稳定性讨论发现系统除了出现正常相和超辐射相之外,还得到了多稳的宏观量子态;受激辐射来自于原子数反转的集体态,单组分的Dicke系统中并没有此现象;受激辐射只能从一组分的原子中产生,而另外的仍保持在普通超辐射状态.通过调整相关的原子-场耦合强度和频率失谐,超辐射和受激辐射态的顺序可以在原子的两个组分之间互换. 相似文献
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Presented is a type-II quantum algorithm for superfluid dynamics, used to numerically predict solutions of the GP equation
for a complex scalar field (spinless bosons) in φ4 theory. The GP equation is a long wavelength effective field theory of a microscopic quantum lattice gas with nonlinear state
reduction. The quantum lattice gas algorithm for modeling the dynamics of the one-body BEC state in 3+1 dimensions is presented.
To demonstrate the method's strength as a computational physics tool, a difficult situation of filamentary singularities is
simulated, the dynamics of solitary vortex-antivortex pairs, which are a basic building block of morphologies of quantum turbulence. 相似文献
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Lettner M Mücke M Riedl S Vo C Hahn C Baur S Bochmann J Ritter S Dürr S Rempe G 《Physical review letters》2011,106(21):210503
Entanglement between stationary systems at remote locations is a key resource for quantum networks. We report on the experimental generation of remote entanglement between a single atom inside an optical cavity and a Bose-Einstein condensate (BEC). To produce this, a single photon is created in the atom-cavity system, thereby generating atom-photon entanglement. The photon is transported to the BEC and converted into a collective excitation in the BEC, thus establishing matter-matter entanglement. After a variable delay, this entanglement is converted into photon-photon entanglement. The matter-matter entanglement lifetime of 100 μs exceeds the photon duration by 2 orders of magnitude. The total fidelity of all concatenated operations is 95%. This hybrid system opens up promising perspectives in the field of quantum information. 相似文献