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arXiv 1903.10366cond-mat.quant-gas
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两组分费米气体相互作用猝灭后动量分布的总能动力学和渐近性

Total Energy Dynamics and Asymptotics of the Momentum Distribution Following an Interaction Quench in a Two-component Fermi Gas

Chen-How Huang, Miguel A. Cazalilla

摘要:

在超冷(两组分费米)气体中原子相互作用的赝势描述中缺少特征动量标度,导致微扰理论的发散。在这里,我们表明,他们也困扰量子淬火后的总能量的动力学计算。一个程序,以消除分歧的设计,它提供了有限的答案淬火后的总能量的时间演化,其中的相互作用强度是斜升根据任意协议。这个分析的一个重要结果是得到了动量分布的渐近尾的时间演化(与Tan的接触有关)和线性相互作用斜坡的接触,作为从突然淬火到绝热极限的交叉中的相互作用斜坡时间的函数。在突然失超极限下,接触在快速振荡之后达到不同于平衡值的稳定值。在绝热极限,接触增长的时间平方,后来饱和到其平衡值的散射长度的最终值。

英文摘要:

The absence of a characteristic momentum scale in the pseudo-potential description of atomic interaction in ultracold (two-component Fermi) gases is known to lead to divergence in perturbation theory. Here we show that they also plague the calculation of the dynamics of the total energy following a quantum quench. A procedure to remove the divergence is devised, which provides finite answers for the time-evolution of the total energy after a quench in which the interaction strength is ramped up according to an arbitrary protocol. An important result of this analysis is the time evolution of the asymptotic tail of the momentum distribution (related to Tan's contact) and the contact for a linear interaction ramp are obtained, as a function of the interaction ramp time in the crossover from the sudden quench to the adiabatic limit are reported. In sudden quench limit, the contact, following a rapid oscillation, reaches a stationary value which is different from the equilibrium one. In the adiabatic limit, the contact grows quadratically in time and later saturates to its equilibrium value for the final value of the scattering length.

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