Open AccessEffects of nonlinearity on quantum resonance ratchet
Author(s) -
Wen-Lei Zhao,
Dou Fu-Quan,
Wang Jian-zhong
Publication year - 2012
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.61.220503
Subject(s) - ratchet , physics , momentum (technical analysis) , ratchet effect , wave packet , angular momentum , nonlinear system , quantum , resonance (particle physics) , quantum mechanics , position and momentum space , classical mechanics , quantum electrodynamics , work (physics) , finance , economics
We investigate the effect of the nonlinear interaction on the quantum resonance ratchet for the periodically kicked Bose-Einstein condensate that is realized on a ring. In the noninteracting case, the wave packet spreads asymmetrically in momentum space, leading to a directed current. We show that for the weak nonlinear interaction, the probability density distribution in momentum space has two peaks which linearly shift to ward positive and negative momentum, respectively. The force periodically acting on each peak is a constant with time evolution. The competition between the motions of the two parts of cold atoms leads to the reduce or the revival of the momentum current. For the strong nonlinearity, the momentum distribution has only one peak which does not shift with time. The force on this peak is almost zero with time evolution, thus the directed current varnishes.