Lecturer: Haggai Landa
Abstract:
The shaping of physical systems by periodic (Floquet) driving is a powerful tool gaining increasing attention - notably in solid-state and atomic systems. However the modelling of nonperturbative effects in a periodically modulated system is challenging due to the necessity of employing time dependent tools beyond perturbation theory, and common approaches proceed by a time independent approximation with effective parameters. It is hence an important question to determine the extent of the validity of such effective descriptions, and the possible directions going beyond it.
I will present a nonperturbative and time-dependent approach to Floquet two-body atomic interactions [1]. With it we find the existence of singular solutions that cannot be seen in a time independent approximation, where poles of the scattering S-matrix cross the real energy axis at a critical drive strength, making the S-matrix nonanalytic. The Floquet singular solutions have common properties with spectral singularities (or exceptional points) and mark a profound change of the system properties.
In particular, I will discuss the application to ultracold atoms and ion-atom hybrid systems [2,3].
[1] H. Landa, arXiv:1708.09828
[2] H. Landa, in preparation.
[3] A. Sykes, H. Landa, and D. Petrov, PRA 95, 062705 (2017).