Paul Corkum and Donghyuk Ko, University of Ottawa and the National Research Council of Canada
Title:Attosecond – the Universal Response of Transparent Matter
Attosecond and high-harmonic pulses are a universal characteristic of transparent media because in all media, continuum states become Volkov states in a sufficiently intense infrared field. Occupying Volkov states, the continuum electrons undergo the oscillatory motion of any free electron in the field. They provide a quantum justification for the semi-classical three-step model.
The three-step model of (1) tunneling, (2) field-driven propagation, and (3) recombination upon recollision, ensures that within its spectrum the pulse carries information on the dynamics of its creation. As I will show, for simple systems (such as Argon), this information can be retrieved by measuring the electron’s quantum trajectories.
In larger systems, the single active electron approximation is violated. In solids, for example, electrons and holes both move, and both contribute to the photon energy of the high harmonics. Ion excitation is also almost certainly a characteristic of molecules, and I will show that it is present in Xenon in intense 1.8µm light.
Attosecond pulses have led to (1) the fastest controlled measurements that we, as humans can make. In addition, we have found (2) a completely new direction of nonlinear optics in which continuum states compliment bound states; (3) a laser-like source of soft X-rays; and in a few cases (4) we can offer time-resolution to collision physics.
Paul Corkum is a Distinguished Research Chair at the University of Ottawa, a member of the Royal Societies of London and Canada and a foreign member of the US National Academy of Science, the Austrian Academy of Science, and the Russian Academy of Sciences. He was awarded the 2017 Royal Medal, for attosecond science, and the National Research Council of Canada’s Schneider Medal. In 2018, Corkum was received both the SPIE Gold Medal, and the Isaac Newton Medal and Prize from the UK Institute of Physics. Recently, the Wolf Foundation selected Corkum as a co-winner of the 2022 Wolf Prize in Physics and the BBVA foundation co-awarded him the frontiers of knowledge award with Anne l’Huillier and Ferenc Krausz, both winners of the 2023 Nobel Prize in Physics.