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1.
Spatiotemporal Bloch states of a spin–orbit coupled Bose–Einstein condensate in an optical lattice 下载免费PDF全文
《中国物理 B》2019,(5)
We study the spatiotemporal Bloch states of a high-frequency driven two-component Bose–Einstein condensate(BEC)with spin–orbit coupling(SOC) in an optical lattice. By adopting the rotating-wave approximation(RWA) and applying an exact trial-solution to the corresponding quasistationary system, we establish a different method for tuning SOC via external field such that the existence conditions of the exact particular solutions are fitted. Several novel features related to the exact states are demonstrated; for example, SOC leads to spin–motion entanglement for the spatiotemporal Bloch states, SOC increases the population imbalance of the two-component BEC, and SOC can be applied to manipulate the stable atomic flow which is conducive to control quantum transport of the BEC for different application purposes. 相似文献
2.
Using a three-dimensional mean-field model we study one-dimensional dipolar Bose–Einstein condensate (BEC) solitons on a weak two-dimensional (2D) square and triangular optical lattice (OL) potentials placed perpendicular to the polarization direction. The stabilization against collapse and expansion of these solitons for a fixed dipolar interaction and a fixed number of atoms is possible for short-range atomic interaction lying between two critical limits. The solitons collapse below the lower limit and escapes to infinity above the upper limit. One can also stabilize identical tiny BEC solitons arranged on the 2D square OL sites forming a stable 2D array of interacting droplets when the OL sites are filled with a filling factor of 1/2 or less. Such an array is unstable when the filling factor is made more than 1/2 by occupying two adjacent sites of OL. These stable 2D arrays of dipolar superfluid BEC solitons are quite similar to the recently studied dipolar Mott insulator states on 2D lattice in the Bose–Hubbard model by Capogrosso-Sansone et al. [B. Capogrosso-Sansone, C. Trefzger, M. Lewenstein, P. Zoller, G. Pupillo, Phys. Rev. Lett. 104 (2010) 125301]. 相似文献
3.
《中国物理 B》2020,(5)
We investigate the properties of Bose–Einstein condensates(BECs) in a two-dimensional quasi-periodic optical lattice(OL) with eightfold rotational symmetry by numerically solving the Gross–Pitaevskii equation. In a stationary external harmonic trapping potential, we first analyze the evolution of matter-wave interference pattern from periodic to quasiperiodic as the OL is changed continuously from four-fold periodic to eight-fold quasi-periodic. We also investigate the transport properties during this evolution for different interatomic interaction and lattice depth, and find that the BEC crosses over from ballistic diffusion to localization. Finally, we focus on the case of eightfold symmetric lattice and consider a global rotation imposed by the external trapping potential. The BEC shows vortex pattern with eightfold symmetry for slow rotation, becomes unstable for intermediate rotation, and exhibits annular solitons with approximate axial symmetry for fast rotation. These results can be readily demonstrated in experiments using the same configuration as in Phys. Rev.Lett. 122 110404(2019). 相似文献
4.
We investigate the energetic and dynamical instability of spin–orbit coupled Bose–Einstein condensate in a deep optical lattice via a tight-binding model. The stability phase diagram is completely revealed in full parameter space, while the dependence of superfluidity on the dispersion relation is illustrated explicitly. In the absence of spin–orbit coupling, the superfluidity only exists in the center of the Brillouin zone. However, the combination of spin–orbit coupling, Zeeman field, nonlinearity and optical lattice potential can modify the dispersion relation of the system, and change the position of Brillouin zone for generating the superfluidity. Thus, the superfluidity can appear in either the center or the other position of the Brillouin zone. Namely, in the center of the Brillouin zone, the system is either superfluid or Landau unstable, which depends on the momentum of the lowest energy. Therefore, the superfluidity can occur at optional position of the Brillouin zone by elaborating spin–orbit coupling, Zeeman splitting, nonlinearity and optical lattice potential. For the linear case, the system is always dynamically stable, however, the nonlinearity can induce the dynamical instability, and also expand the superfluid region. These predicted results can provide a theoretical evidence for exploring the superfluidity of the system experimentally. 相似文献
5.
《中国物理 B》2019,(6)
We investigate domain wall excitations in a two-component Bose–Einstein condensate with two-body interactions and pair-transition effects. It is shown that domain wall excitations can be described exactly by kink and anti-kink excitations in each component. The domain wall solutions are given analytically, which exist with different conditions compared with the domain wall reported before. Bubble-droplet structure can be also obtained from the fundamental domain wall, and their interactions are investigated analytically. Especially, domain wall interactions demonstrate some striking particle transition dynamics. These striking transition effects make the domain wall admit quite different collision behavior, in contrast to the collision between solitons or other nonlinear waves. The collisions between kinks induce some phase shift, which makes the domain wall change greatly. Their collisions can be elastic or inelastic with proper combination of fundamental domain walls. These characters can be used to manipulate one domain wall by interacting with other ones. 相似文献
6.
S. Ritter F. Brennecke K. Baumann T. Donner C. Guerlin T. Esslinger 《Applied physics. B, Lasers and optics》2009,95(2):213-218
A Bose–Einstein condensate is dispersively coupled to a single mode of an ultra-high finesse optical cavity. The system is
governed by strong interactions between the atomic motion and the light field even at the level of single quanta. While coherently
pumping the cavity mode the condensate is subject to the cavity optical lattice potential whose depth depends nonlinearly
on the atomic density distribution. We observe optical bistability already below the single photon level and strong back-action
dynamics which tunes the coupled system periodically out of resonance. 相似文献
7.
Ai-Xia Zhang Li-Xia Cai Zi-Fa Yu Na-Na Chang Si-Qi He Ju-Kui Xue 《Physics letters. A》2019,383(2-3):196-201
We study the dynamics of Bose–Einstein condensate in one-dimensional driven tilted periodic optical lattices by using variational approximation and numerical simulation. Rich phenomena are revealed, including diffusion, self-trapping, breather and soliton, which strongly depend on the atomic interaction, the amplitude of the modulation, the constant force and the phase difference between the Bloch oscillations and the drive. The critical conditions for the dynamical transition from diffusion to self-trapping and for the formation of the soliton are derived analytically. In addition, the phase diagrams of dynamical transitions are presented in full parameters space. We find that the dynamics of the system can be completely controlled by adjusting the constant force, the amplitude of the modulation and the phase difference between the Bloch oscillations and the drive. The results are confirmed by the direct numerical simulation of the full Gross–Pitaevskii equation. 相似文献
8.
A. S. Grankin M. V. Komissarova A. P. Sukhorukov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(12):1633-1636
A variety of nonlinear optical effects arising upon the interaction of a signal beam with a strong pump beam at the second harmonic frequency in a nonlinear Bose-Einstein condensate is studied. Along with the ratio of signal and pump beam widths, the influence of the mutual geometry of the trap and the pump beam profile on the studied processes is investigated. 相似文献
9.
10.
Manipulating transition of a two-component Bose–Einstein condensate with a weak δ-shaped laser 下载免费PDF全文
《中国物理 B》2019,(10)
We theoretically study the transition dynamics of a two-component Bose–Einstein condensate driven by a train of weak δ-shaped laser pulses. We find that the atomic system can experience peculiar resonant transition even under weak optical excitations and derive the resonance condition by the perturbation method. Employing this mechanism, we propose a scheme to obtain an atomic ensemble with desired odd/even atom number and also a scheme to prepare a nonclassical state of the many-body system with fixed atom number. 相似文献
11.
We investigate the Bloch and dipole oscillations of a Bose Einstein condensate (BEC) in an optical superlattice. We show that,
as the effective mass increases in an optical superlattice, the BEC is localized in accordance with recent experimental observations
[J.E. Lye et. al. Phys. Rev. A 75, 061603 (2007)]. In addition, we find that the secondary optical lattice is a useful additional tool to manipulate
the dynamics of the atoms.
相似文献
12.
Z. Oztas 《Physics letters. A》2019,383(6):504-508
We numerically investigate the localization of Bose Einstein condensate (BEC) with spin orbit coupling in a two dimensional bichromatic optical lattice. We study localization in weakly interacting and non-interacting regimes. The existence of stationary localized states in the presence of spin–orbit and Rabi couplings has been confirmed. We find that spin orbit coupling favors localization, whereas Rabi coupling has a slight delocalization effect. 相似文献
13.
Dimensionality serves as an indispensable ingredient in any attempt to formulate low-dimensional physics, and studying the dimensional crossover at a fundamental level is challenging. The purpose of this work is to study the hierarchical dimensional crossovers, namely the crossover from three dimensions (3D) to quasi-2D and then to 1D. Our system consists of a 3D Bose–Einstein condensate trapped in an anisotropic 2D optical lattice characterized by the lattice depths V1 along the x direction and V2 along the y direction, respectively, where the hierarchical dimensional crossover is controlled via V1 and V2. We analytically derive the ground-state energy, quantum depletion and the superfluid density of the system. Our results demonstrate the 3D-quasi-2D-1D dimensional crossovers in the behavior of quantum fluctuations. Conditions for possible experimental realization of our scenario are also discussed. 相似文献
14.
Controllable optical bistability of Bose—Einstein condensate in an optical cavity with Kerr medium 下载免费PDF全文
We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical bistability hysteresis can be controlled by appropriately adjusting the Kerr interaction between the photons. In particular, we show that the optical bistability will disappear when the Kerr interaction exceeds a critical value. 相似文献
15.
16.
Three-dimensional Bose–Einstein condensate vortex soliton sunder optical lattice and harmonic confinements 下载免费PDF全文
We predict three-dimensional vortex solitons in a Bose-Einstein condensate under a complex potential which is the combination of a two-dimensional parabolic trap along the transverse radial direction and a one-dimensional optical-lattice potential along the z axis direction. The vortex solitons are built in the form of layer-chain structure made up of several fundamental vortices along the optical-lattice direction, which were not reported before in the three-dimensional Bose-Einstein condensate. By using the combination of the energy density functional method with the direct numerical simulation, we find three-dimensional vortex solitons with topological charge χ=1, χ=2, and χ=3. Moreover, the macroscopic quantum tunneling and the chirp phenomena of the vortex solitons are shown in the evolution. Thereinto, the occurrence of the macroscopic quantum tunneling provides a possibility for the realization of the quantum tunneling in experiment. Specifically, we manipulate the vortex solitons along the optical lattice direction successfully. The stability limits for dragging the vortex solitons from an initial fixed position to a prescribed location are further pursued. 相似文献
17.
Effects of periodic optical lattice potential on dark solitons in a Bose Einstein condensate 下载免费PDF全文
This paper investigates the dynamics of dark solitons in a
Bose--Einstein condensate with a magnetic trap and an optical
lattice (OL) trap, and analyses the effects of the periodic OL
potential on the dynamics by applying the variational approach based
on the renormalized integrals of motion. The results show that the
dark soliton becomes only a standing-wave and free propagation
of the dark soliton is not possible when the periodic length of the
OL potential is approximately equal to the effective width of the
dark soliton. When the periodic length is very small or very large,
the effects of the OL potential on the dark soliton will be sharply
reduced. Finally, the numerical results confirm these theoretical
findings. 相似文献
18.
利用线性稳定性分析的方法,对光晶格中双组分偶极玻色-爱因斯坦凝聚体(Bose-Einstein condensates,简称BECs)的调制不稳定性进行了研究.得到了光晶格中双组分偶极BECs原子系统调制不稳定性区域的分布与在位相互作用和由偶极-偶极相互作用所导致的格点间BECs相互作用之间的关系.结果显示,格点间BECs的相互作用对光晶格中双组分偶极BECs的调制不稳定性有较大的影响,这可为实际应用中如何操控双组分偶极BECs提供有用的信息.
关键词:
光晶格
双组分玻色-爱因斯坦凝聚体
调制不稳定性
偶极-偶极相互作用 相似文献
19.
20.
Yongping Zhang Maren Elizabeth Mossman Thomas Busch Peter Engels Chuanwei Zhang 《Frontiers of Physics》2016,11(3):118103
The experimental and theoretical research of spin–orbit-coupled ultracold atomic gases has advanced and expanded rapidly in recent years. Here, we review some of the progress that either was pioneered by our own work, has helped to lay the foundation, or has developed new and relevant techniques. After examining the experimental accessibility of all relevant spin–orbit coupling parameters, we discuss the fundamental properties and general applications of spin–orbit-coupled Bose–Einstein condensates (BECs) over a wide range of physical situations. For the harmonically trapped case, we show that the ground state phase transition is a Dicke-type process and that spin–orbit-coupled BECs provide a unique platform to simulate and study the Dicke model and Dicke phase transitions. For a homogeneous BEC, we discuss the collective excitations, which have been observed experimentally using Bragg spectroscopy. They feature a roton-like minimum, the softening of which provides a potential mechanism to understand the ground state phase transition. On the other hand, if the collective dynamics are excited by a sudden quenching of the spin–orbit coupling parameters, we show that the resulting collective dynamics can be related to the famous Zitterbewegung in the relativistic realm. Finally, we discuss the case of a BEC loaded into a periodic optical potential. Here, the spin–orbit coupling generates isolated flat bands within the lowest Bloch bands whereas the nonlinearity of the system leads to dynamical instabilities of these Bloch waves. The experimental verification of this instability illustrates the lack of Galilean invariance in the system. 相似文献