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Published on: May 30, 2014
Quantum path interference in the wavelength dependence of high-harmonic generation
K Schiessl1, K L Ishikawa, E Persson
1Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria. klaus@concord.itp.tuwien.ac.at
Physical Review Letters
|February 1, 2008
Summary
High-harmonic generation shows unexpected fluctuations with fundamental driver wavelength. These rapid changes stem from quantum path interferences involving multiple electron orbits.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Quantum Optics
- Nonlinear Optics
Background:
- High-harmonic generation (HHG) is a key process for producing extreme ultraviolet and X-ray radiation.
- The intensity of HHG typically exhibits a smooth power-law dependence on the fundamental driver field's wavelength.
- Understanding HHG is crucial for applications in spectroscopy, attosecond science, and materials characterization.
Purpose of the Study:
- To investigate the detailed dependence of high-harmonic generation intensity on the fundamental driver field's wavelength.
- To identify the physical mechanisms responsible for observed deviations from the smooth power-law behavior.
- To analyze the role of quantum interferences in shaping the HHG spectrum.
Main Methods:
- Theoretical modeling of high-harmonic generation spectra.
- Numerical simulations of electron trajectories and recombination dynamics.
- Analysis of quantum path interferences across a range of fundamental wavelengths (lambda).
Main Results:
- Observed strong and rapid fluctuations in HHG intensity superimposed on the expected power-law dependence.
- Identified quantum path interferences as the origin of these fine-scale wavelength fluctuations.
- Found significant contributions from up to five distinct returning electron orbits to the interference patterns.
Conclusions:
- Quantum path interferences play a critical role in the fine structure of high-harmonic generation spectra.
- The number of contributing electron orbits influences the complexity and magnitude of spectral fluctuations.
- This detailed understanding of HHG wavelength dependence can guide experimental control and optimization.
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