论文标题
在Bose-Hubbard模型中Gutzwiller近似之外的量子波动
Quantum fluctuations beyond the Gutzwiller approximation in the Bose-Hubbard model
论文作者
论文摘要
这项工作从Bose-Hubbard（BH）模型（BH）模型的最新知识和最新的方法论发展中汲取灵感，这项工作涉及对晶格Bose气体的集体动力学的研究，这是通过对其基本激励的量子描述来超出平均景点图片的。通过Bogoliubov在Gutzwiller方法中的BH动作进行二次化进行的Hamiltonian量化，可以将理论的有效作用扩展到均值固定解决方案的波动中，并预先鉴定出识别次数的主要衰减模式和其他效果的可能性，从而将其预订的可能性延长到二阶的二阶。该量子描述将标准的Bogoliubov方法扩展到了超级流体BOSE系统的研究，以组成较高的激发分支，包括在超级流体阶段的HIGGS模式，并确定其物理含义以及可以考虑其实验表征的适当可观察的物理含义。量化程序的最终目的是确定基本数量作为冷凝物的耗竭和有效的超流体分数的确定，而在强相互作用的制度中，均不是通过平均场描述或未完全表征的有效超流体分数。
Taking inspiration from the state-of-the art knowledge of the Bose-Hubbard (BH) model and recent methodological developments in its fermionic counterpart, this work deals with the study of the collective dynamics of a lattice Bose gas beyond the mean-field picture through a quantum description of its elementary excitations. The Hamiltonian quantization, performed via a Bogoliubov quadratization of the BH action within the Gutzwiller approach, allows to expand the effective action of the theory up to second order in the fluctuations around the mean-field solution, as well as to prefigure the possibility of identifying the main decay vertices of the collective modes and other effects that are not evident at the second-order level. This quantum description extends the standard Bogoliubov approach to the study of superfluid Bose systems for comprising higher excitation branches, including the Higgs mode in the superfluid phase, and identifies their physical meaning together with appropriate observables which could be taken into consideration for their experimental characterization. The ultimate aim of the quantization procedure is the determination of fundamental quantities as the depletion of the condensate and the effective superfluid fraction, which are not accessible by a mean-field description or not completely characterized in the regime of strong interactions.
