中国物理B ›› 2019, Vol. 28 ›› Issue (1): 10307-010307.doi: 10.1088/1674-1056/28/1/010307

• SPECIAL TOPIC—Recent advances in thermoelectric materials and devices • 上一篇    下一篇

Periodically modulated interaction effect on transport of Bose-Einstein condensates in lattice with local defects

Kun-Qiang Zhu(朱坤强), Zi-Fa Yu(鱼自发), Ji-Ming Gao(高吉明), Ai-Xia Zhang(张爱霞), Hong-Ping Xu(徐红萍), Ju-Kui Xue(薛具奎)   

  1. College of Physics and Electronics Engineering, Northwest Normal University, Lanzhou 730070, China
  • 收稿日期:2018-08-28 修回日期:2018-10-29 出版日期:2019-01-05 发布日期:2019-01-05
  • 通讯作者: Ju-Kui Xue E-mail:xuejk@nwnu.edu.cn
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11764039, 11475027, 11865014, 11305132, and 11274255), the Natural Science Foundation of Gansu Province, China (Grant No. 17JR5RA076), and the Scientific Research Project of Gansu Higher Education, China (Grant No. 2016A-005).

Periodically modulated interaction effect on transport of Bose-Einstein condensates in lattice with local defects

Kun-Qiang Zhu(朱坤强), Zi-Fa Yu(鱼自发), Ji-Ming Gao(高吉明), Ai-Xia Zhang(张爱霞), Hong-Ping Xu(徐红萍), Ju-Kui Xue(薛具奎)   

  1. College of Physics and Electronics Engineering, Northwest Normal University, Lanzhou 730070, China
  • Received:2018-08-28 Revised:2018-10-29 Online:2019-01-05 Published:2019-01-05
  • Contact: Ju-Kui Xue E-mail:xuejk@nwnu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11764039, 11475027, 11865014, 11305132, and 11274255), the Natural Science Foundation of Gansu Province, China (Grant No. 17JR5RA076), and the Scientific Research Project of Gansu Higher Education, China (Grant No. 2016A-005).

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摘要：

We theoretically investigate the periodically modulated interaction effect on the propagation properties of a traveling plane wave in a Bose-Einstein condensate (BEC) trapped in a deep annular lattice with local defects both analytically and numerically. By using the two-mode ansatz and the tight-binding approximation, a critical condition for the system preserving the superfluidity is obtained analytically and confirmed numerically. We find that the coupled effects of periodic modulated atomic interactions, the quasi-momentum of the plane wave, and the defect can control the superfluidity of the system. Particularly, when we consider the periodic modulation in the system with single defect, the critical condition for the system entering the superfluid regime depends on both the defect and the momentum of the plane wave. This is different from the case for the system without the periodic modulation, where the critical condition is only determined by the defect. The modulation and quasi-momentum of the plane wave can enhance the system entering the superfluid regime. Interestingly, when the modulated amplitude/frequency, the defect strength, and the quasi-momentum of the plane wave satisfy a certain condition, the system will always be in the superfluid region. This engineering provides a possible means for studying the periodic modulation effect on propagation properties and the corresponding dynamics of BECs in disordered optical lattices.

关键词: Bose-Einstein condensate, periodic modulation, superfluidity, lattice with defects

Abstract:

We theoretically investigate the periodically modulated interaction effect on the propagation properties of a traveling plane wave in a Bose-Einstein condensate (BEC) trapped in a deep annular lattice with local defects both analytically and numerically. By using the two-mode ansatz and the tight-binding approximation, a critical condition for the system preserving the superfluidity is obtained analytically and confirmed numerically. We find that the coupled effects of periodic modulated atomic interactions, the quasi-momentum of the plane wave, and the defect can control the superfluidity of the system. Particularly, when we consider the periodic modulation in the system with single defect, the critical condition for the system entering the superfluid regime depends on both the defect and the momentum of the plane wave. This is different from the case for the system without the periodic modulation, where the critical condition is only determined by the defect. The modulation and quasi-momentum of the plane wave can enhance the system entering the superfluid regime. Interestingly, when the modulated amplitude/frequency, the defect strength, and the quasi-momentum of the plane wave satisfy a certain condition, the system will always be in the superfluid region. This engineering provides a possible means for studying the periodic modulation effect on propagation properties and the corresponding dynamics of BECs in disordered optical lattices.

Key words: Bose-Einstein condensate, periodic modulation, superfluidity, lattice with defects

中图分类号:  (Dynamic properties of condensates; collective and hydrodynamic excitations, superfluid flow)

  • 03.75.Kk
03.75.Lm (Tunneling, Josephson effect, Bose-Einstein condensates in periodic potentials, solitons, vortices, and topological excitations) 67.85.Hj (Bose-Einstein condensates in optical potentials)