Computational Laser Physics

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Computational Laser Physics Armin Scrinzi and
Ferenc Krausz (Project outline for SFB ACOS)
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Motivation short powerful light pulses

• Full control over the laser electric field

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Powerful pulse what it does to an atom
The hydrogen electron density in a strong field
Time (optical cycles) -1 -½ 0 ½ 1
Pulse parameters 4 x 1014 W/cm2 5 fs
FWHM (simulation)
Extremely non-perturbative laser-matter
interaction
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Accelerate electrons to MeV energies
Focus very high power laser pulse into a thin
plasma
Laser-plasma interaction with relativistic
motion of charges
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Attosecond time-resolved measurments
Auger process and its streaking image
(simulation)
Dynamics of electrons in atomic and molecular
valence orbitals
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Present theoretical work in our group
I) Models for attosecond measurement and dynamics
Instrumental for the interpretation of
attosecond dynamics experiments E.g.
Time-resolved inner shell spectroscopy Drescher
et al., Nature 2002 Quantum coherence in
time-resolved Auger measurement Smirnova et
al., Phys. Rev. Lett. 2003.
II) Short pulse propagation and high harmonic
generation Numerical simulation of 3d
non-linear propagation E.g. Phase-controled
light pulses Baltuska et al., Nature 2003
High harmonic imaging Yakovlev et al., Phys.
Rev. Lett. 2003.
III) Numerical simulations of multi-electron
dynamics MCTDHF --- Multi-configuration
time-dependent Hartree-Fock Theory
computational implementation in 1d for an
arbitray number of electrons Proof of the
method and convergence tests Zhangellini et al.,
J. Phys. B, 2004
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Expected experimental developments

• Higher pulse energies and repetition rates
• gt higher precision experiments
• More detailed control over the laser field
• gt control atomic excitation and imaging
• Shorter and stronger attosecond XUV pulses
• gt non-linear XUV (pump-probe) experiments

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I Non-linear wave propagation

• Wave propagation is a work horse of current
  research
• Higher intensities will pose new challenges
• Develop new algorithms for existing approaches
• Wave propagations on a grid
• Particle-in-Cell code for laser-plasma
  interactions

• Space discretization
• Time-integration schemes
• Dealing with (physical) instabilities
• Cylindrical symmetry gt Fast Fourier-Hankel
  transforms ?

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II MCTDHF
Multi-electron dynamics Multi-Configuration
Time-Dependent Hartree-Fock
Ansatz
Adaptive expansion functions jj(x,t) Much
shorter expansions -- Nonlinear time-evolution
equations

• Theory mathematics approximation properties
  of the ansatz
• Optimal solution algorithms for the given ansatz
• Adaptive discretization of R3
• Compact representation of js
• - Another layer of non-linearity

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III TDDFT
Time-Dependent Density Functional Theory
DFT determine the electron density by solving
an uncorrelated multi-electron problem with an
exchange correlation potential
VXC(r,t) Potentially much more efficient than
all alternative methods

• Investigate the failure of TDDFT
• for laser-matter interactions (in its present
  realizations)
• Systematically search for suitable VXC (compare
  to MCTDHF)

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Long range perspectives

• Build up a network of expertise for
• Attosecond multi-electron dynamics
• Computations as key technology for
• Simulation of experiments and verification of
  models
• Provide mathematical foundations for
• Pragmatic solutions employed in applications
• Strategic outside collaborations
• Wave packet dynamics H. D. Meyer, Heidelberg
  
• Density functional theory E. K. U. Gross,
  Berlin