Controlling Floquet states on ultrashort time scales

Area of Science:

• Ultrafast laser science
• Quantum optics
• Atomic physics

Background:

• Floquet engineering enables optical control of matter using intense laser fields.
• Current limitations restrict Floquet theory to long laser pulses (many optical cycles).
• The minimum pulse duration for realizing Floquet states remains an open question.

Purpose of the Study:

• To investigate the shortest driving pulse duration for observing Floquet states.
• To explore the influence of pulse duration on Floquet engineering.
• To extend the application of Floquet theory to few-cycle laser pulses.

Main Methods:

• Ionization of Neon (Ne) atoms using few-femtosecond laser pulses of controlled duration.
• Analysis of photoelectron spectra to identify Floquet-like sidebands.
• Application of an analytical model based on Floquet theory.

Main Results:

• Floquet states were observed with driving fields as short as 10 optical cycles.
• An analytical model successfully explained the finite lifetime of driven states for pulses down to 2 cycles.
• Control over Floquet-like sideband amplitude and number was demonstrated by varying pulse intensity, frequency, and duration.

Conclusions:

• Floquet engineering is feasible with significantly shorter laser pulses than previously thought.
• Laser pulse duration is a controllable parameter in Floquet engineering.
• These findings expand the capabilities of ultrafast optical control of matter.