Bose-Hubbard model in a ring-shaped optical lattice with high filling factors
Bose-Hubbard model in a ring-shaped optical lattice with high filling factors
复制标题
高填充因子环形光学晶格中的 Bose-Hubbard 模型
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
D. Jezek
中科院分区：
文献类型：
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作者：
H. Cataldo;D. Jezek
研究了环形光晶格中玻色-爱因斯坦凝聚体的高势垒量子隧穿机制。通过基变换，将“涡旋”Bloch态与Wannier型局域波函数相联系，得到了广义的Bose-Hubbard哈密顿量。除了通常的跳跃率条款，这样的哈密顿量考虑到相互作用驱动的隧穿过程，这是在高填充因子发挥主要作用，当标准的跳跃率参数原来是负的。通过计算Bloch态的能量和原子流，我们证明了这样的跳跃率必须用一个包含相互作用驱动的跳跃率的附加贡献的有效跳跃率参数来代替.这种贡献在高填充因子下是至关重要的，因为它保留了有效跳频速率参数的正性。类万尼尔态和超流基态的每个粒子的能量之间的能级交叉被解释为在每个晶格位置处具有宏观占据态的配置的过渡的签名。
The high-barrier quantum tunneling regime of a Bose-Einstein condensate confined in a ring-shaped optical lattice is investigated. By means of a change of basis transformation, connecting the set of 'vortex' Bloch states and a Wannier-like set of localized wave functions, we derive a generalized Bose-Hubbard Hamiltonian. In addition to the usual hopping rate terms, such a Hamiltonian takes into account interaction-driven tunneling processes, which are shown to play a principal role at high filling factors, when the standard hopping rate parameter turns out to be negative. By calculating the energy and atomic current of a Bloch state, we show that such a hopping rate must be replaced by an effective hopping rate parameter containing the additional contribution an interaction-driven hopping rate. Such a contribution turns out to be crucial at high filling factors, since it preserves the positivity of the effective hopping rate parameter. Level crossings between the energies per particle of a Wannier-like state and the superfluid ground state are interpreted as a signature of the transition to configurations with macroscopically occupied states at each lattice site.