Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Departmental Colloquium - Attosecond Physics: From the Gas to the Condensed Matter Phase

Thomas Brabec
University of Ottawa, Department of Physics

Date: Friday, November 7th, 2014
Time: 1:30 pm
Location: Stirling A


High harmonic generation in gases takes place when atoms or molecules are exposed to intense laser fields. As a result, electrons are tunnel ionized and undergo a quiver motion during which they can revisit the parent nucleus; upon recombination a high harmonic (xuv) coherent photon is emitted. As the radiation is emitted in sub-cycle (attosecond) bursts, HHG presents the basis of attosecond physics which has received a lot of attention recently. The “Holy Grail” of attosecond science is making movies on the attosecond timescale and Angstrom length scale to resolve fundamental processes such as the making and breaking of molecular bonds.

Recently high harmonic generation (HHG) has been demonstrated in the condensed matter phase. In our talk we discuss the different mechanisms driving HHG in solids. We theoretically and experimentally identify the dominant mechanism and show that it is closely related to the process responsible for HHG in atomic and molecular gases: an electron hole pair is generated through tunnel ionization; electron and hole are first driven apart and then accelerated back towards each other by the laser field. A harmonic photon is generated when electron and hole recollide and recombine.
The similarity between HHG in gases and solids opens the possibility to translate many of the techniques developed for atomic attosecond physics to the condensed matter phase. Various potential applications, such as bandgap tomography and attosecond electronics, will be discussed.