Quantum-optical Properties of High-Harmonic Generation

The emission of high-order harmonics of intense femtosecond lasers has long been understood as a result of a short-lived and rapidly oscillating “quantum antenna”: the result of the dynamical interference of the wavefunctions of an accelerated electron and that of its correlated hole, setup by an intense laser field during its interaction with matter. Ever since its discovery and understanding in the 1980s-90s, the emitted light has always been considered as a classical electromagnetic field, even though it is typically extremely weak. In the last five years or so, however, the investigation of the quantum-optical properties of high-harmonic generation has gained significant traction. In my talk I will introduce the unlikely merge of high-field attosecond science and quantum optics, and the oxymoron within it. I will present our latest work aimed at uncovering and inducing quantum-optical properties of the emitted high-harmonics, as well as our application of an attosecond metrology technique to resolve the field oscillations and other temporal structures of femtosecond bright squeezed vacuum, a quantum optical state.

Speaker: Giulio Vampa, National Research Council of Canada, Ottawa