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BNL Physics Colloquia

Attosecond Clocking and Control of Strong Field Quantum Trajectories

by Prof. Louis F. DiMauro (The Ohio State University)

US/Eastern
Description

Nearly thirty years ago, a simple and intuitive unified view of intense laser-atom interactions was introduced. The model is based on a semi-classical description where a bound electron is tunnel ionized by the strong optical field, followed by propagation under the influence of the strong field and finally driven back to interact with the core. This simple view has become known as the three-step or rescattering model and is responsible for the production of high energy electrons and photons, multiple ionization and the formation of attosecond light pulses. The coherent process is defined by initial conditions set by tunnel ionization which defines the physical observables for the subsequent steps.

Feynman has taught us that the outcome of a quantum process is dictated by the sum over all the quantum trajectories that contribute to it. Naturally, when analyzing experiments, we often refer to these individual trajectories even though they have not been measured individually. In this talk, we introduce a Quantum Trajectory Selector (QTS) method capable of resolving individual quantum orbits responsible for strong-field phenomena in real time. Using an attosecond XUV pulse, we select the moment of ionization and measure the rate for both rescattered electron emission and double ionization driven by a phase locked near infrared field. We show that there is an intensity-dependent shift in the ionization time associated with double ionization, and we clock this shift as it varies by 250 as. The QTS provides a new attosecond paradigm for expanding our understanding of recollision-driven physics.

Zoom link:  https://bnl.zoomgov.com/j/1605020278?pwd=cHJ1bDRuK1FDNnZLSnpxVkZhcDQ3QT09