Atoms, Lasers and Computers

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Atoms, Lasers and Computers
Rainer Grobe Intense Laser Physics Theory
Unit Illinois State University
www.phy.ilstu.edu/ILP
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see a factor 2
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Professor George Skadron
Physics Chair 1986 - 1997
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Skadrons physics niche for ISU
challenge specialization (without too
narrow expertise) top notch research
agenda solution Computational
Physics
gt unique education for our undergraduate
students
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Traditional Physics
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Nature
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Nature
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Nature
Nature
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The new problem Laws of nature are established
but we cant solve the equations
.... solution Computers can calculate
numbers example x 2 - x gt
x0.611857....
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Modern Physics
Laws of Nature
Laws of Nature
theory
simulation
Laws of Nature
Laws of Nature
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Structure of the laws of nature
examples for Y position temperature
field
know Y(t8 00 ) system at 8 00 goal
Y(t 9 00) predict future at 9 00
examples for F Newton Maxwell Dirac
?
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Continuity of time unjustified assumption Has
mathematics gone too far by requiring Dt -gt 0 Do
we really need the strict limit
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No
limits
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Discretization of the laws of nature (8)
no limits gt choose Dt finite (Dt 1 sec)
repeat the forward step 3600 times
Computers can do it !
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Advantages of Computer Experimentscompared to
laboratory experiments
safer cheaper exactly reproducible all
ingredients controllable simultaneous
measurements insight into ultrafast mechanisms
most importantly going beyond present
technology
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Impact of computer experiments on research areas
nonlinear dynamics and chaos space-plasma
physics solid state physics laser science
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3 examples of breakthroughs due to computer
simulations
1996 Adiabatons 2000
Cycloatoms 2003 Birth of matter
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I. Optical signal transmission
Dream
output (identical to input)
input message
Reality
output (distorted damped)
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Challenge prevent losses distortion
Second beam can protect the original field !
control the optical properties of medium
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Computer simulations of adiabatons
after
before
bodyguard
input signal
output signal
prediction by computer simulation
1994 experimental verification (Stanford
Univ.) 1996
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Could adiabatons become important?
applications in optical switches
wavelength converter non-demolition signal
replicator pulse-shape controller
long distance transmission
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Storage and recall of optical information
storage
energy levels
medium in ground state
medium in excited state
recall
Jennifer Csesznegi and RG, Phys. Rev. Lett. 1997
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Laboratory experiments are presently viewed as
important
1997 Discovery of this effect in computer
simulations 1999 Experimental verification at
Harvard measured speed of light only 17 m/s
(factor of 20 million!) New York Times (Front
page on February 18) Glossy article in Time
Magazine
Appreciation of the value of computer simulations
is growing ..
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II. Atom in strong laser fields
Laser intensities in W/cm2 laser pointer
103 laser welding 106 world record
1019 1000 lighting bolts
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Robert Wagner (Computer Physics Major 1998-2002)

• 13 Publications
• 14 Conference presentations
• Barry Goldwater Scholarship
• USA All Academic Team
• Leroy Apker Award in 2002
• now a graduate student at Princeton

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Power and curse of quantum mechanics
most accurate description of nature example
electrons mag. moment experiment
1.0015965219 Dirac 1.0015965220
When does an atom decay ? ............. no answer
Where is the electron ? ............. no
answer
"I think I can safely say that nobody understands
quantum mechanics."
Richard Feynman
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Difficulties with quantum mechanics
conceptual provides only probabilities
technical difficult to solve
Alternative approach
use Newtonian mechanics
approximate quantum wave function by an
ensemble of quasiparticles
...does it work ?
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Quantum mechanics Classical ensemble !
wave function for an atom
ensemble density for the same atom
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Patience is better than brute force
Past belief

Trick use the resonance
magnetic field laser field
very fast electron
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Use resonance to accelerate electron
3 108 m/s
speed of light
electrons velocity
80 of c
108 m/s
magnetic field strength
laser field frequency cyclotron frequency
gt no need for expensive high-power
lasers
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Computer simulation of a hydrogen atom in a
strong laser and magnetic field
1013 W/cm2
1010 Gauss
magnetic field strengths earth 1
magnet 102 neutron star 1015
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Time evolution of a cycloatom
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Articles from Science Writers about Cycloatoms
Ivars Peterson of Science News Ring around the
Proton Science News Vol. 157, No.18, 287 (2000)
David Ehrenstein of Physical Review Focus Fast
Electrons on the Cheap Physical Review Focus 5
(April 6, 2000)
Daniel S. Burgess of Photonics Spectra Physicists
Play Ring-Around-the-Atom Photonics Spectra 34,
26 (2000)
Herczeg János of Élet es Tudomány Atomi
Hulahopp Élet Tudomány Vol. 18, May 5 (2000)
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Half resonance
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Could cycloatoms become important?
Laser input
cycloatoms generate new light with very high
frequencies
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Evolution of the electrons spin
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III. E mc 2 in space time resolution
Dream to simulate how a particle is born from
pure energy
1928 Dirac equation 1932 Positrons
discovered 1940 Progress in interpretation
Feynman/Schwinger 1973 Application to quarks 1989
First experiment conversion of laser -gt
matter 2001 Correlated wave function
formalism 2003 First computer simulations
Questions can now be addressed Where is the
electron born? What is its wave function? What
are its coherence properties?
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The birth of an electron-positron pair
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The birth of an electron-positron pair
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Are e_ and e born at same location?
electron positrons uncertainty cloud
no simultaneous occurence
Electron and positron are born on top of each
other
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Acknowledgment
ISU support Honors program URG
program College of AS
Collaborators at ISU Students
PostDocs Faculty Robert Wagner Harsha
Wanare Charles Su Peter Peverly Sunish
Menon George Rutherford Shannon Mandel Piotr
Krekora Michael Marsalli Allen Lewis
Hiroshi Matsuoka Michael Bell Tony
Piraino ......