Semiclassical quench dynamics of Bose gases in optical lattices
Semiclassical quench dynamics of Bose gases in optical lattices
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DOI：
10.1103/physreva.99.023622
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发表时间：
2019-02-20
影响因子：
2.9
通讯作者：
Danshita, Ippei
中科院分区：
文献类型：
--
作者：
Nagao, Kazuma;Kunimi, Masaya;Danshita, Ippei
我们分析了玻色-哈伯德模型在量子突然猝灭到弱相互作用状态后的时间演化。具体来说，在京都大学最近的一项实验的激励下，我们数值模拟了早期动力学和现场相互作用能量的重新分布，这是在立方光学晶格中从单占据莫特绝缘体状态开始的超冷玻色气体的非平衡动力学中观察到的。为了计算与实验情况相对应的短时动力学，我们对三次晶格上的玻色-哈伯德模型采用截断- wigner近似。我们表明，我们的半经典方法定量地再现了快速再分配动力学。我们进一步分析了Bose-Hubbard模型在具有大填充因子的方形晶格上密度-密度相关在等时间的空间扩展。当系统在相干状态下初始制备时，我们发现相关波包在相关函数中的传播速度强烈依赖于最终的相互作用强度，并且以初等激发最大群速度的两倍为界。相反，当系统初始处于莫特绝缘子状态时，波包的传播速度与最终相互作用强度基本无关。
We analyze the time evolution of the Bose-Hubbard model after a sudden quantum quench to a weakly interacting regime. Specifically, motivated by a recent experiment at Kyoto University, we numerically simulate redistribution of the kinetic and on-site interaction energies at an early time, which was observed in nonequilibrium dynamics of ultracold Bose gases in a cubic optical lattice starting with a singly occupied Mott-insulator state. In order to compute the short-time dynamics corresponding to the experimental situation, we apply the truncated-Wigner approximation to the Bose-Hubbard model on a cubic lattice. We show that our semiclassical approach quantitatively reproduces the fast redistribution dynamics. We further analyze spatial spreading of density-density correlations at equal time in the Bose-Hubbard model on a square lattice with a large filling factor. When the system is initially prepared in a coherent state, we find that a propagation velocity of the correlation wave packet in the correlation function strongly depends on the final interaction strength, and it is bounded by twice the maximum group velocity of the elementary excitations. In contrast, when the system is initially in a Mott-insulator state, the propagation velocity of the wave packet is approximately independent of the final interaction strength.