2009/05/20 by G. A. McKenna, R. Nepstad, McKenna, G. A. +8
Engineering · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Laser Design and Applications #Laser-Matter Interactions and Applications #quant-ph
paper · pdf · doi:10.48550/arxiv.0905.3280
11 pages, 8 figures
arxiv created 2009/05/20 · arxiv updated 2009/12/01
We investigate the effect of dynamic electron correlation on high-harmonic generation in helium atoms using intense visible light (λ=390nm). Two complementary approaches are used which account for correlation in an approximate manner: time-dependent density-functional theory and a single-active-electron model. For intensities I~1014 W/cm2, the theories are in remarkably good agreement for the dynamic polarization and harmonic spectrum. This is attributed to a low-frequency collective mode together with a high-frequency single-electron response due to the nuclear singularity, both of which dominate electron correlation effects. A time-frequency analysis is used to study the timing and emission spectrum of attosecond bursts of light. For short pulses, we find a secondary maximum below the classical cut-off. The imprint of the carrier-envelope-phase, for the time-integrated spectral density appears at frequencies above the high-frequency drop-off, consistent with previous studies in the infrared λ~800nm.