Controlling Floquet states on ultrashort time scales

TL;DR

This paper demonstrates that Floquet states can be established within just 10 cycles of ultrashort laser pulses, extending Floquet engineering into the ultrafast, few-cycle regime and enabling new control over matter at petahertz frequencies.

Contribution

It shows that Floquet states can be realized with pulses as short as 10 cycles, and introduces control of Floquet sidebands via pulse duration, expanding the scope of Floquet engineering.

Findings

Floquet states form within 10 cycles of the driving pulse.

Floquet states can be sustained with pulses as short as 2 cycles.

Population of Floquet sidebands depends on pulse duration, intensity, and frequency.

Abstract

The advent of ultrafast laser science offers the unique opportunity to combine Floquet engineering with extreme time resolution, further pushing the optical control of matter into the petahertz domain. However, what is the shortest driving pulse for which Floquet states can be realised remains an unsolved matter, thus limiting the application of Floquet theory to pulses composed by many optical cycles. Here we ionized Ne atoms with few-femtosecond pulses of selected time duration and show that a Floquet state can be established already within 10 cycles of the driving field. For shorter pulses, down to 2 cycles, the finite lifetime of the driven state can still be explained using an analytical model based on Floquet theory. By demonstrating that the population of the Floquet sidebands can be controlled not only with the driving laser pulse intensity and frequency, but also by its duration, our results add a new lever to the toolbox of Floquet engineering.