Quantum control with intense X-ray pulses: A theoretical approach

该项目的目标是将最优控制扩展到X射线区域，即超越基于近红外激光脉冲的成熟的相干控制方案。这种新体制下的脉冲通常具有比载波频率小得多的可用于脉冲整形的带宽。将探索在这些条件下是否以及如何实现最优控制。理论研究将基于所谓的包络哈密顿量。这个哈密顿量将载流子频率的电场振荡的影响与激光脉冲包络的影响分开。在建立高频包络哈密顿量之后，必须确定与包络哈密顿量有关的最合适的控制方案，并进行数值实现。为了深入了解最优控制机制，将用摄动理论来描述动力学。摄动法能否直接用于最优控制还有待研究。虽然这些研究大多是针对测试用例进行的，但最终X射线最优控制的性能必须应用于实际系统，有待确定。

The goal of this project is to extend optimal control to the X-ray regime, i.e., beyond the well established coherent control schemes based on near infrared laser pulses. Pulses in this new regime have typically bandwidths, available for pulse shaping, which are much smaller than the carrier frequency. It will be explored if and how optimal control can be made possible under these conditions. The theoretical investigations will be based on the so-called envelope Hamiltonian. This Hamiltonian separates the effect of the oscillations of the electric field with the carrier frequency from the effect of the envelope of the laser pulse. Thereby, it directly takes advantage of the aforementioned characteristic difference of bandwidth and carrier frequency in the high-frequency domain.After formulating the envelope Hamiltonian for high frequencies the most suitable control scheme in connection with the envelope Hamiltonian have to be identified and implemented numerically. In order to gain insight into the optimal control mechanisms the dynamics will be described in terms of a perturbation theory. It remains to be studied whether the perturbative approach can be directly used for optimal control. Whereas most of these studies will be done for test cases, ultimately the performance of the X-ray optimal control has to be applied to realistic systems, to be identified.