Control of Electrons by Few-Cycle Intense Laser Pulses

强烈的，相位稳定的，飞秒激光脉冲只包括几个光学周期（几个周期脉冲）提供了一个独特的新工具，用于操纵物质中的电子。脉冲的强振荡电场使价电子在准经典轨道上移动，但是在亚光学周期时间尺度上的相互作用对于核运动来说太短暂了。因此，在小量子系统（例如原子、分子、簇、表面、纳米系统）中电子的运动可以被控制，而原子核被固定在适当的位置。该提案概述了在这一迅速崛起的领域的深入研究计划。强载波包络相位稳定（CEP稳定）、少周期脉冲的突破提供了精确定义的强电场光学波形。这些完全受控的几个周期脉冲首次允许将强驱动电子运动控制到量子极限，具有亚光学周期（< 1 fs）的时间分辨率和近原子尺度（~10^-10 m）的空间分辨率。现在有可能实现一种新型的强场电子过程的相干控制，这些过程对CEP固有地敏感。重要的是要强调，是电场波形而不是脉冲强度包络被利用来控制系统。这些场在与物质中电子态相关的自然时空尺度（即< 10^-10 m和< 10^-15 s）上提供了对电子的控制--这为量子控制开辟了令人兴奋的新可能性。我们将进行的控制将电子运动与离子（核）运动隔离开来，后者被有效地冻结在脉冲持续时间的时间尺度上。因此，在未发生变化的物质中控制准经典电子态是可行的。本建议涉及这些新的光学技术的发展及其在物质中电子过程的研究和控制中的应用。国际上对这一领域日益增长的兴趣突出了这一建议的及时性，例如在瑞典（隆德）、法国（萨克雷）、美国（博尔德、伯克利、俄亥俄州）以及最值得注意的德国（MPG-MPQ、Garching），都开始了重大努力。所有这些项目的动机都是实现物质中最高程度的量子控制的前景，这可能导致化学，材料和光学科学的新突破。我们的项目目标包括通过受控电子电离演示选择性键裂，优化亮度和最小化相干XUV和非相干硬X射线光源中的脉冲持续时间，通过电离双电子系统创建自旋纠缠电子态以及开发紧凑的激光相位探测器。

Intense, phase-stabilised, femtosecond laser pulses comprising only a few optical cycles ( few-cycle pulses) offer a unique new tool for the manipulation of electrons in matter The strong oscillating electric field of the pulse moves valence electrons in quasi-classical trajectories, but the interaction on the sub optical-cycle timescale is too brief for nuclear motion to occur. Thus the motion of the electrons in small quantum systems (e.g. atoms, molecules, clusters, surfaces, nanosystems) can be controlled whilst the nuclei are fixed in position. This proposal outlines an in-depth programme of research in this rapidly emerging area.The breakthrough of intense carrier envelope phase-stabilised (CEP stabilised), few-cycle pulses provides precisely defined strong electric field optical waveforms. These fully controlled few-cycle pulses permit, for the first time, the control of strongly driven electron motion down to the quantum limit with sub-optical period (< 1 fs) temporal resolution and near atomic scale (~10^-10m) spatial resolution. It is now possible to implement a new type of coherent control of strong field electron processes that are inherently sensitive to the CEP. It is important to stress that it is the electric field waveform, rather than the pulse intensity envelope , that is harnessed to control the system. Control of electrons is provided by these fields at the natural spatial and temporal scales relevant to electronic states in matter (i.e. < 10^-10m and < 10^-15s) - this opens up exciting new possibilities in quantum control. The control we will exercise isolates electron motion from the ion (nuclear) motion, the latter being effectively frozen on the timescale of the pulse duration. Thus the control of quasi-classical electron states within otherwise unaltered material will be feasible.This proposal concerns the development of these new optical techniques and their application to the investigation and control of electron processes in matter. The timeliness of this proposal is underlined by the growing interest in this field internationally with major efforts starting up, for instance in Sweden (Lund), France (Saclay), USA (Boulder, Berkeley, Ohio) and most notably in Germany (MPG-MPQ, Garching). The motivation for all these projects is the prospect of achieving the highest degree of quantum control in matter that can lead to new breakthroughs in chemical, material and optical sciences. Our project objectives include demonstration of selective bond cleaving via controlled electron recollision, optimisation of brightness and minimisation of pulse duration in coherent XUV and incoherent hard X-ray light sources, creation of spin entangled electronic states via ionisation of two-electron systems and development of compact detectors for laser phase.