We use nonlinear optimal control simulation to systematically examine how to suppress wave-packet spreading with strong nonresonant near-infrared (NIR) laser pulses through a case study of a vibrational wave packet in the $B$ state of ${\mathrm{I}}_2$. As the degree of spreading of the vibrational wave packet is controllable by adjusting the pump pulse shape, the vibrational wave packet may be regarded as a prototype system to study spreading suppression by using nonresonant laser pulses. We quantitatively define spreading suppression in terms of the probability of finding the wave packet in the analytically defined, initially excited state at every vibrational period. From optimal control simulation and simulation by using model Gaussian pulse trains that mimic optimal pulses, we conclude that a simple periodic NIR pulse train without highly tuned temporal widths, amplitudes, or irradiation timings can almost perfectly stop the wave-packet spreading over a long control period, provided that the degree of spreading is not too large.

中文翻译：

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强非谐振激光脉冲抑制波包扩展的最优控制

我们使用非线性最优控制仿真系统地研究了如何通过强非共振近红外 (NIR) 激光脉冲抑制波包扩展，通过一个振动波包的案例研究 $乙$ 的状态 ${\mathrm{一世}}_2$. 由于振动波包的扩展程度可以通过调整泵浦脉冲形状来控制，因此可以将振动波包作为研究非共振激光脉冲扩展抑制的原型系统。我们根据在每个振动周期中在解析定义的初始激发态中找到波包的概率来定量定义传播抑制。从最优控制仿真和使用模拟最优脉冲的模型高斯脉冲串进行仿真，我们得出结论，没有高度调谐的时间宽度、幅度或辐照时间的简单周期性 NIR 脉冲串几乎可以完美地阻止波包在长控制中的传播期间，只要传播程度不太大。