Control of Electrons by Few-Cycle Intense Laser Pulses

只有几个光周期(几个周期脉冲)的高强度、相位稳定的飞秒激光脉冲为操纵物质中的电子提供了一种独特的新工具。脉冲的强振荡电场以准经典轨迹移动价电子，但亚光周期时间尺度上的相互作用太短，不可能发生核运动。因此，电子在小量子系统(如原子、分子、团簇、表面、纳米系统)中的运动可以在原子核固定的情况下被控制。这项提议勾勒出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的脉冲首次实现了对强驱动电子运动的控制，其时间分辨率为亚光周期(&lt；1fs)，空间分辨率为近原子尺度(~10^-10m)。现在有可能实现对强场电子过程的一种新型相干控制，这些过程对CEP具有内在的敏感性。需要强调的是，控制系统的是电场波形，而不是脉冲强度包络。电子的控制是由这些场在与物质中的电子态相关的自然空间和时间尺度上提供的(即&lt；10^-10m和&lt；10^-15s)--这为量子控制打开了令人兴奋的新可能性。我们将要实施的控制将电子运动与离子(核)运动隔离开来，后者实际上被冻结在脉冲持续时间的时间尺度上。因此，控制物质中的准经典电子态将是可行的。这项提议涉及到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显了这一建议的及时性，并开始了重大努力，例如在瑞典(Lund)、法国(Saclay)、美国(Boulder、Berkeley、俄亥俄州)以及最引人注目的德国(MPG-MPQ、GARCHING)。所有这些项目的动机都是希望在物质上实现最高程度的量子控制，从而在化学、材料和光学科学方面取得新的突破。我们的项目目标包括通过受控的电子再碰撞演示选择性键断裂，优化相干XUV和非相干硬X射线光源的亮度和最小化脉冲持续时间，通过两电子系统的电离创建自旋纠缠电子态，以及开发用于激光相位的紧凑型探测器。

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.