共查询到19条相似文献,搜索用时 78 毫秒
1.
研究玻色-爱因斯坦凝聚的相变特征,证明了粒子间存在弱排斥相互作用的玻色系统的玻色-爱因斯坦凝聚是二级相变。 相似文献
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光晶格中玻色-爱因斯坦凝聚体的自旋和磁研究 总被引:1,自引:0,他引:1
近年应用光晶格(optical lattice)控制原子玻色-爱因斯坦凝聚体(BEC)的研究取得了突破性的进展。德国Munich研究小组首次在三维光晶格中观察到了超冷原子从BEC超流状态向Mott insulator状态的量子相变。这样的量子相变现象不仅具有重大的理论研究价值,而且为BEC的实际应用提供了新的途径。文章介绍了作者近来在光晶格中BEC的自旋和磁特性方面的一些研究进展,并探讨了它们在磁传感器及量子计算中的可能应用。 相似文献
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囚禁在光学晶格中的旋量凝聚体由于其长的相干性和可调控性,使其成为时下热点的多比特量子计算的潜在候选载体,清楚地了解该体系的自旋和磁性的产生和调控就显得尤为重要.本文主要从理论上回顾了光晶格原子自旋链的磁性的由来和操控手段.从激光冷却原子出发,制备旋量玻色-爱因斯坦凝聚体,并装载进光晶格,最后实现原子自旋链,对整个过程的理论研究进行了综述;就如何产生和操控自旋激发进行了详细探讨,其中包括磁孤子的制备;讨论了如何将原子自旋链应用于量子模拟.对光学晶格中的磁激发研究将会对其在冷原子物理、凝聚态物理、量子信息等各方向的应用起指导性作用. 相似文献
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利用含时变分法研究了二维光晶格中准二维玻色-爱因斯坦凝聚中的调制不稳定性. 在平均场近似下, 由准二维Gross-Pitaevskii方程出发, 利用变分法给出了调制波振幅和相位所满足的时间演化方程, 通过求解时间演化方程和能量分析法给出了发生调制不稳定性的条件, 决定于平面波振幅, 晶格强度, 调制波的波矢量和原子之间的两体相互作用. 相似文献
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研究了平面Bessel型光晶格(BL)中双组分玻色-爱因斯坦凝聚(BECs)体系的基态解.从描述三维(3D)BECs体系的动力学方程Gross-Pitaevskii方程(GPE)出发,当垂直方向囚禁频率远大于平面上囚禁频率时,得到了描述2D-BECs体系的动力学方程.利用双组分BECs体系中原子之间相互作用与BL强度相互平衡的条件,得到了平面BL光晶格中2D-GPE的一组基态精确解,给出了基态的原子数分布,总原子数和能量与原子之间相互作用强度及BL势的关系.相对于单组分BEC体系,由于不同组分原子相互作用的存在,使得BL光晶格中双组分BECs基态具有更丰富的结构.当不存在不同组分原子之间的相互作用时,模型简化到单组分体系,并给出了相应的基态解,原子数分布和能量.
关键词:
Bessel型光晶格
基态解
双组分玻色-爱因斯坦凝聚 相似文献
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发展准离散多尺度法结合紧束缚近似,解析地研究了局陷于光晶格势阱中凝聚体的非线性动力学性质.结果发现,系统中出现稳定的对称包络孤子外,还可观察到一种新的非线性元激发:扭结包络隙孤子.有趣的是,该隙孤子并不传播且局域在初始位置,其幅度可通过光晶格势阱的晶格常数和势阱深度来调控.相应的实验方案是:通过改变形成光晶格势阱的两交叉耦合激光束之间的夹角和(或)激光光强来调控扭结包络隙孤子的幅度. 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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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
11.
With the method of Green's function, we investigate the energy
spectra of two-component ultracold bosonic atoms in optical
lattices. We find that there are two energy bands for each
component. The critical condition of the superfluid-Mott insulator
phase transition is determined by the energy band structure. We
also find that the nearest neighboring and on-site interactions fail
to change the structure of energy bands, but shift the energy
bands only. According to the conditions of the phase transitions,
three stable superfluid and Mott insulating phases can be found by
adjusting the experiment parameters. We also discuss the possibility
of observing these new phases and their transitions in further experiments. 相似文献
12.
Excitations of optomechanically driven Bose Einstein condensates in a cavity: Photodetection measurements 下载免费PDF全文
We present a detailed study to analyze the Dicke quantum phase transition within the thermodynamic limit for an optomechanically driven Bose-Einstein condensate in a cavity. The photodetection-based quantum optical measurements have been performed to study the dynamics and excitations of this optomechanical Dicke system. For this, we discuss the eigenvalue analysis, fluorescence spectrum and the homodyne spectrum of the system. It has been shown that the normal phase is negligibly affected by the mechanical mode of the mirror while it has a significant effect in the superradiant phase. We have observed that the eigenvalues and the spectra both exhibit distinct features that can be identified with the photonic, atomic and phononic branches. In the fluorescence spectra, we further observe an asymmetric coherent energy exchange between the three degrees of freedom of the system in the superradiant phase arising as a result of optomechanical interaction and Bloch-Siegert shift. 相似文献
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We study the quantum phase transition of ultracold atoms in the honeycomb optical lattice. The Hamiltonian of ultracold bosonic atoms in the honeycomb optical lattice is derived. We take the mean-field approximation and further solve the Hamiltonian with the numerical diagonalization method. We obtain the phase diagram and find that the Mort-insulator (MI), density wave (DW) and modulated superfluid (MS) phases appear. Furthermore, the phase diagram is analyzed according to the order parameter and the average number of particles. 相似文献
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CHEN Hai-Jun LI Hao-Cai XUE Ju-Kui 《理论物理通讯》2008,49(6):1519-1526
The stability of the ground state of two-component Bose-Einstein condensates (BEGs) loaded into the central well of an axially symmetric Bessel lattices (BLs) potential with attractive or repulsive atoms interactions is studied using the time-dependent Gross-Pitaevskii equation (GPE). By using the variational method, we find that stable ground state of two-component BEGs can exist in BLs. The BLs's depth and the intra-species atom interaction play an important role in the stability of ground state. The collapse of two-component BEGs in BLs is also studied and a collapse condition for trapped two-component BEGs is obtained. It is shown that the two-component BEGs exhibit rich collapse dynamics. That is, the two-component BEGs can collapse in the system with both intra- and inter-attractive, or with intra-attractive and inter-repulsive, or with intra-repulsive and inter-attractive atom interactions. Furthermore, the control of the collapse of the two-component BEGs in BLs is discussed in detail. The stability diagram of the ground state in parameter space is obtained. The results show that the collapse of two-component BEGs can be controlled by temporal modulation of the atom interaction. 相似文献
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The higher-order interactions of Bose-Einstein condensate in multi-dimensional optical lattices are discussed both analytically and numerically.It is demonstrated that the effects of the higher-order atomic interactions on the sound speed and the stabilities of Bloch waves strongly depend on the lattice strength.In the presence of higher-order effects,tighter and high-dimensional lattices are confirmed to be two positive factors for maintaining the system's energetic stability,and the dynamical instability of Bloch waves can take place simultaneously with the energetic instability.In addition,we find that the higher-order interactions exhibit a long-range behavior and the long-lived coherent Bloch oscillations in a tilted optical lattice exist.Our results provide an effective way to probe the higher-order interactions in optical lattices. 相似文献
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We investigate the strongly interacting lattice Bose gases on a lattice with two-body interaction of nearest neighbors characterized by pair tunneling.The excitation spectrum and the depletion of the condensate of lattice Bose gases are investigated using the Bogoliubov transformation method and the results show that there is a pair condensate as well as a single particle condensate.The various possible quantum phases,such as the Mott-insulator phase(MI),the superfluid phase(SF) of an individual atom,the charge density wave phase(CDW),the supersolid phase(SS),the pair-superfluid(PSF) phase,and the pair-supersolid phase(PSS) are discussed in different parametric regions within our extended Bose-Hubbard model using perturbation theory. 相似文献
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Quantum Entanglement of Many Distant Bose-Einstein Condensates in an Optical Lattice by Interference
We propose a scheme to generate maximally entangled states of two distant Bose-Einstein condensates, which are trapped in different potential wells of a one-dimensional optical lattice. We show how such maximally entangled state can be used to test the Bell inequality and realize quantum teleportation of a Bose-Einstein condensate state. The scheme proposed here is based on the interference of Bose-Einstein condensates leaking out from different potential wells of optical lattice. It is briefly pointed out that this scheme can be extended to generate maximally entangled Greenberger-Horne-Zeilinger (GHZ) states of 2m (m >1) distant Bose-Einstein condensates. 相似文献