Attosecond Spectroscopy- From Universality to singularity

Wednesday, November 6, 2019 - 3:00pm to 4:00pm

Speaker:  Gal Orenstein, Weizmann

Program Description:

Strong-field light-matter interactions have revolutionized our ability to manipulate quantum systems on extremely short time scales. During the strong-field interaction, the basic properties of the medium can be significantly modified – altering the instantaneous electronic structure in atomic and molecular systems within less than one optical cycle.

Strong field ionization followed by recollision provide a unique pump-probe measurement, combining sub-Angstrom spatial and attosecond temporal resolution. This self-probing scheme enables us to re-visit one of the most fundamental strong-field phenomena: field-induced tunnel ionization. We employ high-harmonic generation to probe the electron wavefunction during field-induced tunnelling through a potential barrier. This study provides direct insight into the basic properties of field-induced tunnelling, revealing signatures of its non-adiabatic temporal evolution.

Next, we advance HHG spectroscopy to condensed matter systems. Our study reveals the underlying attosecond dynamics that dictates the temporal evolution of carriers in multi-band solid-state systems. We demonstrate that when the electron-hole relative velocity approaches zero, enhanced constructive interference leads to the appearance of spectral caustics in the HHG spectrum. Introducing the role of the dynamical joint density of states we identify its mapping into the spectrum, exhibiting singularities at the spectral caustics. By studying these singularities, we probe the structure of multiple unpopulated high conduction bands.

 

Attosecond Spectroscopy- From Universality to singularity
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