Optical fields can now be controlled with similar degrees of freedom as microwave fields for many decades already: we can now control not just the pulse envelope but also the optical carrier field. With few cycle laser pulses, this allows steering of electrons in unprecedented ways. I will give an overview over recent experiments we performed mainly with the atomically thin material graphene. Here we can drive the intraband motion of electrons but also interband transitions. For the intense ultrashort fields we employ, these processes become intricately coupled - a hallmark of strongfield physics. In particular, we could observe subsequent coherent Landau-Zener transitions, leading to Landau-Zener-Stückelberg-Majorana interferometry, representing fully coherent electron dynamics in a room-temperature material. In the second part of the talk, we will shine light on the graphene-gold interface and how it will add to the currents we can excite. Because of the different symmetries involved, we can disentangle virtual and real carrier excitations. With these insights, we have recently demonstrated a first Boolean logic gate based on two laser pulses carrying the logic information in the carrier envelope phase, which might bring lightwave or petahertz electronics closer to reality.

TBA

The referent will describe some recent work on applying Effective Field Theory (EFT) methodology to three different physically interesting systems. First he will explain the philosophy and general methodology of EFT. He will then present three short vignettes. The first has to do with techniques for systematically computing the EFT parameters from a given more fundamental description. The second will show how EFT can be used to understand the behavior of quantum fields in an inflationary background, with applications to light scalar fields and the inflaton itself. And in the third, the referent will show how EFT ideas can be applied to systematically improve a numerical technique for quantum field theory known as Hamiltonian truncation.

Liquids are usually described within classical physics, whereas solids require the tools of quantum mechanics. I will show how in nanoscale systems this distinction no longer holds. At these scales, liquid flows may in fact exhibit quantum effects as they interact with electrons in the solid walls. I will first discuss the quantum friction phenomenon, where charge fluctuations in the liquid interact with electronic excitations in the solid to produce a hydrodynamic friction force. Using many-body quantum theory, we predict that this effect is particularly important for water flowing on carbon-based materials, and we obtain experimental evidence of the underlying mechanism from pump-probe terahertz spectroscopy. I will then show how the theory can be pushed one step further to describe hydrodynamic Coulomb drag – the generation of electric current by a liquid in the solid along which it flows. This phenomenon involves a subtle interplay of electrostatic and electron-phonon interactions, and suggests strategies for designing materials with low hydrodynamic friction. Bio: Nikita Kavokine obtained a Bachelor in Chemistry and a Master in Theoretical Physics from Ecole Normale Supérieure (ENS) in Paris. He continued at ENS for his PhD, in the group of Prof. Lydéric Bocquet, working on both theory and experiments in nanoscale fluid dynamics. He then obtained a Flatiron Research Fellowship and spent a year in New York, learning advanced numerical methods for condensed matter systems. He is now a postdoctoral fellow at the Max Planck Institute for Polymer Research. His research is at the interface between ‘hard’ and ’soft’ condensed matter, focussing on the quantum behavior of liquids near solid surfaces.