Quantum Floquet theory: An introduction

Systems with time-dependent Hamiltonians are not constrained to energy conservation. Hence, the dynamics of driven physical systems can be significantly different to its static counterpart. Then, driven systems are a new platform where exciting phenomena can be discovered. However, analytical solutions of the dynamics of driven systems are extremely rare and it is typically difficult to gain intuition. Quantum Floquet theory provides a tractable mathematical framework to study periodically driven systems in the form of perturbative expansions in the driving frequency, which is the cornerstone of Floquet engineering.