Periodically driven quantum systems

Single-particle or many-body quantum systems exposed to a strong time-periodic driving force, such as ultracold atoms in periodically shaken optical lattices, often not only exhibit a surprisingly complex behavior, but also reveal new phenomena which have no counterparts in time-independent equilibrium systems. A powerful theoretical tool for understanding these effects is offered by the Floquet approach, which enables one to transfer many familiar concepts known from quantum systems governed by a time-independent Hamiltonian to systems subjected to periodic or almost periodic driving.



Our group has a long-standing record of contributions to this Floquet picture. Among others, we are addressing the following topics:

  • Classical-quantum correspondence for periodically driven systems, and their semi-classical quantization: "Floquet time crystals"

  • Pseudo-adiabatic response of periodically driven quantum systems to "slow" parameter changes
  • Coherent control of periodically driven many-body systems

  • Periodic thermodynamics: Thermalization and pre-thermalization of  periodically driven many body-systems
  • Macroscopic wave functions for periodically driven Boson systems: "Floquet condensates"

These activities constitute contributions to the Research Unit FOR 2921: "Fundamental Aspects of Statistical Mechanics and the Emergence of Thermodynamics in Non-equilibrium Systems" of the Deutsche Forschungsgemeinschaft (DFG).