High-order harmonic generation from Rydberg atoms in inhomogeneous fields

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Optics
• Ultrafast Science

Background:

• High-order harmonic generation (HHG) is a key process for generating ultrashort light pulses.
• Rydberg atoms are highly sensitive to external fields, offering unique properties for HHG.
• Spatial inhomogeneity of driving laser fields is often neglected but can significantly impact HHG dynamics.

Purpose of the Study:

• To theoretically investigate the effect of spatial inhomogeneity of the driving field on HHG from Rydberg atoms.
• To analyze the underlying physics responsible for spectral modifications in inhomogeneous fields.
• To explore the potential for generating isolated attosecond pulses using this phenomenon.

Main Methods:

• Theoretical investigation using classical and quantum-mechanical models.
• Analysis of high-order harmonic generation spectra.
• Simulation of electron dynamics under spatially inhomogeneous laser fields.

Main Results:

• Spatially inhomogeneous fields extend the harmonic cutoff to the multi-cycle regime for Rydberg atoms, unlike homogeneous fields limited to few-cycle regimes.
• The underlying physics of cutoff extension in inhomogeneous fields was elucidated through classical and quantum models.
• Optimizing field inhomogeneity allows control over electron dynamics, leading to a smooth supercontinuum generation.

Conclusions:

• Spatial inhomogeneity of the driving field is crucial for extending the harmonic cutoff in Rydberg atom HHG.
• This extended cutoff facilitates the generation of isolated attosecond pulses from multi-cycle laser fields.
• The findings offer a pathway for enhanced control over ultrafast phenomena in atomic systems.