Atoms, Lasers and Computers

1. Atoms, Lasers and Computers Rainer Grobe Intense Laser Physics Theory Unit Illinois State University www.phy.ilstu.edu/ILP

2. see a factor 2

3. Professor George Skadron Physics Chair 1986 - 1997

4. Skadron’s physics niche for ISU challenge: • specialization (without too narrow expertise) • top notch research agenda solution: Computational Physics => unique education for our undergraduate students

5. experiment theory experiment experiment Traditional Physics ? Nature ? Nature ? ? Nature Nature

6. D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 Wx(h,w,x,l)= F(x,y,z,t,t)T1567 Wx(h,w,x,l)= F(x,y,z,t,t)T1567 D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 j(i,a,q)=i2a3/q Wx(h,w,x,l)= F(x,y,z,t,t)T1567 Wx(h,w,x,l)= F(x,y,z,t,t)T1567 j(i,a,q)=i2a3/q j(i,a,q)=i2a3/q j(i,a,q)=i2a3/q D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 Wx(h,w,x,l)= F(x,y,z,t,t)T1567 Wx(h,w,x,l)= F(x,y,z,t,t)T1567 j(i,a,q)=i2a3/q j(i,a,q)=i2a3/q Wx(h,w,x,l)= F(x,y,z,t,t)T1567 D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 j(i,a,q)=i2a3/q D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 GT(x,p,o)=0T&^ GT(x,p,o)=0T&^ GT(x,p,o)=0T&^ j(i,a,q)=i2a3/q Wx(h,w,x,l)= F(x,y,z,t,t)T1567 j(i,a,q)=i2a3/q GT(x,p,o)=0T&^ j(i,a,q)=i2a3/q D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 GT(x,p,o)=0T&^ j(i,a,q)=i2a3/q j(i,a,q)=i2a3/q GT(x,p,o)=0T&^ D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 xh,w,x,l)= F(x,y,z,t,t)T1567 GT(x,p,o)=0T&^ &^ j(i,a,q)=i2a3/q GT(x,p,o)=0T&^ j(i,a,q)=i2a3/q D17=F(x,y,z,t,t)T1567D17=F(x,y,z,t,t)T1567 The new problem Laws of nature are established but: we can’t solve the equations .... solution: Computers can calculate numbers example: x = 2 - x =>x=0.611857....

7. simulation simulation Modern Physics Laws of Nature Laws of Nature theory simulation Laws of Nature Laws of Nature

8. = F [ Y(t) ] = function of Y rate of change of Y Structure of the laws of nature examples for Y: position temperature field know: Y(t=8 00 ) system at 8 00 goal: Y(t= 9 00) predict future at 9 00 examples for F: Newton Maxwell Dirac ? ? Continuity of time = unjustified assumption Has mathematics gone too far by requiring Dt -> 0 Do we really need the strict limit

9. ∞ No limits

10. Y(t+Dt) = Y(t) + F[Y(t)] Dt Y(t) present 8 00 future 8 00 + 1sec time 8 00 9 00 Discretization of the laws of nature (∞) no limits: => choose Dt finite (Dt = 1 sec) repeat the forward step 3600 times Computers can do it !

11. 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

12. Impact of computer experiments on research areas nonlinear dynamics and chaos space-plasma physics solid state physics laser science

13. 3 examples of breakthroughs due to computer simulations 1996 : Adiabatons 2000 : Cycloatoms 2003 : Birth of matter

14. wave = frequency & amplitude change amplitude: pulse can carry information medium medium input message I. Optical signal transmission Dream: output (identical to input) input message Reality: output (distorted & damped)

15. Challenge: prevent losses & distortion input almost no output medium medium output input Second beam can protect the original field ! “control the optical properties of medium”

16. Computer simulations of adiabatons before after bodyguard input signal output signal • prediction by computer simulation : 1994 • experimental verification (Stanford Univ.) : 1996

17. Could adiabatons become important? applications in • optical switches • wavelength converter non-demolition signal replicator • pulse-shape controller • long distance transmission

19. 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

20. 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 ..

21. II. Atom in strong laser fields Laser intensities in W/cm2 • laser pointer: 10–3 • laser welding: 106 • world record: 1019 ≈ 1000 lighting bolts

22. 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

23. P.A.M. Dirac Power and curse of quantum mechanics most accurate description of nature: example: electron’s 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

24. 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 ?

25. nucleus electron cloud Quantum mechanics ≈ Classical ensemble ! wave function for an atom ensemble density for the same atom

26. strong laser only => fast electrons => electron oscillates magnetic field only => electron orbits in circle + = Patience is better than brute force Past belief: Trick: use the resonance magnetic field laser field very fast electron

27. Use resonance to accelerate electron 3 108 m/s speed of light electron’s velocity 80% of c 108 m/s magnetic field strength laser field frequency = cyclotron frequency => no need for expensive high-power lasers

28. 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

29. Time evolution of a cycloatom

30. 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)

31. Half resonance

32. w3 w2 wL wL w1 Could cycloatoms become important? Laser input cycloatoms generate new light with very high frequencies

33. Evolution of the electron’s spin

34. 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 -> 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?

35. The birth of an electron-positron pair

36. The birth of an electron-positron pair

37. Are e_ and e+ born at same location? electron & positron’s uncertainty cloud no simultaneous occurence Electron and positron are born “on top of each other”

38. Acknowledgment ISU support Honors’ program URG program College of A&S Collaborators at ISU StudentsPostDocsFaculty 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 ......