Attosecond Physics

Joint Workshop with FOCUS (University of Michigan)

November 20-22 2003

Organizers: Paul Corkum and Ferenc Krausz

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Schedule

Thursday, Friday, Saturday

Participants

 Abstracts

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 Map showing Hillis Library

 

 

Online Talks

Baltuska

Bandrauk

Brabec

C.-Dreismann

 Chang

 Cocke

Cundiff

Doerner

Drescher

Hastings

 Hutchinson

 Ivanov
Kienberger

Lein

Leone

 L'Huillier

Lin

Malinovskaya 

Midorikawa

Milosevic

Moncton

Mueller

Mukamel 

 Murnane

Naumova

Niikura

 Paulus

Power 

Rayner 

 Salières

Scrinzi 

 Shvets

 Sokolov

Tsakiris 

Ullrich 

Villeneuve

 Walmsley

 Wickenhauser

 Yanovsky

 Zeidler

 
 

 

Workshop Participants

Dr. Philippe Balcou
ENSTA - Ecole Polytechnique
Chemin de la Huniere
91761 Palaiseau cedex, France
balcou@ensta.fr
 
Dr. Andrius Baltuska
Vienna University of Technology
Gusshausstrasse 27/387
A-1040 Vienna, Austria
andrius.baltuska@tuwien.ac.at
 
Prof. Andre D. Bandrauk
Faculte des Sciences
Univ de Sherbrooke
2500, boul. Université
Sherbrooke, Que, J1K 2R1,Que, Canada
Andre.Bandrauk@USherbrooke.ca
 
Thomas Brabec
Physics Department
University of Ottawa
150, Louis Pasteur
Ottawa, ON, K1N 6N5
brabec@uottawa.ca
 
Prof. Philip H. Bucksbaum
University of Michigan
FOCUS Center
Ann Arbor, MI 48109-1120
phb@umich.edu
 
Prof. C. Aris C.-Dreismann
Institute of Chemistry
Technical University Berlin
Stranski Laboratory
Strasse des 17 Juni 112
Berlin, D-10623 Germany
dreismann@chem.TU-Berlin.de
 
Dr. Lew Cocke
Physics Department
Kansas State University
Manhattan, KS 66506
cocke@phys.ksu.edu
 
Dr. Paul Corkum
National Research Council of Canada
100 Sussex Drive
Ottawa, Ontario, K1A 0R6 Canada
Paul.Corkum@nrc.ca

Prof. Steven T. Cundiff
JILA/University of Colorado
440 UCB
Boulder, CO 80309-0440
cundiffs@jila.colorado.edu

Dr. Louis F. DiMauro
Department of Chemistry
Brookhaven National Laboratory
Upton, NY 11973
dimauro@bnl.gov
Prof. Reinhard Doerner
University of Frankfurt
August Euler St. 6
Frankfurt, 60486 Germany
doerner@hsb.uni-frankfurt.de
 
Dr. Markus Drescher
Universitaet Bielefeld
Universitaetsstr. 25
Bielefeld, 33615 Germany
drescher@physik.uni-bielefeld.de
 
Prof. Dietrich Habs
Ludwig-Maximilinas-University
Am Coulombwall 1
85748 Garching
Ambergerstr. 15 81679 Munich, Germany
Dieter.Habs@physik.uni-muenchen.de
 
Dr. Jerome. B. Hastings
Assistant Director 
Stanford Linear Accelerator Center 
SLAC Mail Stop
Stanford, California, 94305 
jerome.hastings@stanford.edu
 
Prof. Henry Hutchinson
CCLRC Rutherford Appleton Laboratory
Chilton, Oxfordshire, OX11 0QX, UK
h.hutchinson@rl.ac.uk
 
Dr. Misha Ivanov
National Research Council of Canada
100 Sussex Drive
Ottawa, Ontario, K1A 0R6 Canada
Misha.Ivanov@nrc.ca
 
Prof. David M. Jonas
Department of Chemistry and Biochemistry
University of Colorado at Boulder
215 UCB
Boulder, CO 80309-0215
david.jonas@colorado.edu
Prof. Franz X. Kaertner
Massachusetts Institute of Technology
77 Massachusetts Ave.
Cambridge, MA 02139
kaertner@mit.edu
 
Prof. Ursula Keller
ETH Hnggerberg, HPT E16.2
ETH Zrich
Zrich, 8093 Switzerland
keller@phys.ethz.ch
 
Dr. Reinhard Kienberger
Vienna University of Technology
Gusshausstr. 27/387
A-1040 Wien, Austria
kienberger@tuwien.ac.at
 
Prof. Ferenc Krausz
Director, Center for Advanced Light Sources
Photonics Institute
Vienna University of Technology
Gusshausstr. 27/387
A-1040 Wien, Austria
krausz@tuwien.ac.at
 
Dr. Manfred Lein
Max Planck Institute for the Physics of Complex Systems
Noethnitzer Str. 38
Dresden, 01187 Germany
lein@mpipks-dresden.mpg.de
 
Prof. Stephen R. Leone
Department of Chemistry
University of California, Berkeley
209 Gilman Hall
Berkeley, CA 94720
srl@cchem.berkeley.edu

Prof. Anne L'Huillier
Department of Physics
Lund Institute of Technology
S-22100 Lund, Sweden
Anne.LHuillier@fysik.lth.se

Prof. Chii-Dong Lin
Department of Physics
Kansas State University
Cardwell Hall
Manhattan, KS 66506
cdlin@phys.ksu.edu
 
Dr. Katsumi Midorikawa
RIKEN
Hirosawa 2-1
Wako
Saitama, 351-0198 Japan
kmidori@riken.jp
 
Dr. Nenad Milosevic
Vienna University of Technology
Gusshaussstrasse 27/387
1040 Vienna, Austria
nmilosev@pop.tuwien.ac.at
 
D. E. Moncton
Massachusetts Institute of Technology
Cambridge, MA 02139
dem@mit.edu

Prof. Shaul Mukamel
Department of Chemistry
516 Rowland Hall, Suite RH434
University of California
Irvine, CA 92697-2025
smukamel@uci.edu

H.-G. Muller
Amolf FOM Institute for Atomic and Molecular Physics
Kruislaan 407
1098 SJ Amsterdam, The Netherlands
muller@amolf.nl
Professor Margaret Murnane
JILA
University of Colorado at Boulder
Boulder, CO 80309-0440
murnane@jila.colorado.edu
Dr. Hiromichi Niikura
National Research Council of Canada
100 Sussex Drive
Ottawa, Ontario, K1A 0R6 Canada
Hiromichi.Niikura@nrc.ca
 
Prof. Gerhard G. Paulus
Department of Physics
Texas A&M University
College Station, TX 77843
ggp@physics.tamu.edu
ggp@mpq.mpg.de
 
Dr. David M. Rayner
National Research Council of Canada
100 Sussex Drive
Ottawa, ON, K1A 0R6, Canada
David.Rayner@nrc.ca

Dr. Pascal Salières
CEA-SPAM
Centre d'Etudes de Saclay
Gif-sur-Yvette, 91191 France
salieres@drecam.cea.fr

Prof. Kenneth J. Schafer
Louisiana State University
Department of Physics & Astronomy
Tower Drive
Baton Rouge, Louisiana 70803-4001
kschafe@lsu.edu
 
Dr. Armin Scrinzi
Photonics Institute
Technical University of Wien
Gusshausstrasse 27/387
Vienna, 1040 Austria
scrinzi@tuwien.ac.at
 
Prof. Alexei V. Sokolov
Physics Department
Texas A&M University
College Station, TX 77843-4242
sokol@physics.tamu.edu
 
Dr. George D. Tsakiris
Max-Planck-Institut fur Quantenoptik
Hans-Kopfermann Str. 1
Garching, D-85748 Germany
tsakiris@mpq.mpg.de
 
Dr. Thomas Tschentscher
Deutsches Elektronen-Synchrotron DESY
Notkestrasse 85
Hamburg, 22607 Germany
thomas.tschentscher@desy.de
 
Prof. Joachim Ullrich
Max-Planck-Institut fuer Kernphysik
Postfach 103980
Heidelberg, D-69029 Germany
joachim.ullrich@mpi-hd.mpg.de
 
Dr. David M. Villeneuve
National Research Council
100 Sussex Drive
Ottawa, ON, K1A 0R6 Canada
david.villeneuve@nrc.ca
 
Prof. Ian A. Walmsley
Clarendon Laboratory
University of Oxford
Parks Road
Oxford OX1 3PU, U.K.
i.walmsley@physics.ox.ac.uk

Dr. Alfons Weber
Chemistry Division
National Science Foundation
4201 Wilson Boulevard
Arlington, VA 22230
aweber@nsf.gov

Mr. Dirk Zeidler
National Research Council
100 Sussex Dr.
Ottawa, ON K1A 0R6 Canada
Dirk.Zeidler@nrc.ca

FOCUS

Mr. Claudiu Genes
307 Thompson, 107
University of Michigan
Ann Arbor, MI 48104
cgenes@umich.edu
 
Dr. Svetlana Malinovskaya
University of Michigan
500 E. University Avenue
Ann Arbor, MI 48109
smalinov@umich.edu
 
Dr. Natalia Naumova
University of Michigan-CUOS
2200 Bonisteel Blvd.
Rm. 6106/ERB I Bldg.
Ann Arbor, MI 48109-2099
naumova@engin.umich.edu
 
Dr. John Nees
University of Michigan-CUOS
2200 Bonisteel Blvd.
Rm. 1012, Gerstacker
Ann Arbor, MI 48109-2099
nees@eecs.umich.edu
 
Dr. Santosh N. Pisharody
500 East University
University of Michigan
Ann Arbor, MI 48109-1120
pisharod@umich.edu
 
Mr. Erik Power
2200 Bonisteel Boulevard
University of Michigan
IST Building, Room 2117
Ann Arbor, MI 48109
eppower@eecs.umich.edu
 
Prof. David A. Reis
Department of Physics
University of Michigan
500 E. University
Ann Arbor, MI 48109
dreis@umich.edu
 
Prof. Gennady Shvets
Illinois Institute of Technology
3101 South Dearborn Street
LS 146D
Chicago, IL 60616
gena@fnal.gov
 
Dr. Victor Yanovsky
University of Michigan
1006 Gerstaker Build
2200 Bonisteel Blvd.
Ann Arbor, MI 48109
vpy@eecs.umich.edu

Attendees

Prof. Zenghu Chang
116 Cardwell Hall
Physics Department
Kansas State University
Manhattan KS 66506
chang@phys.ksu.edu
 
Prof. Kristan L. Corwin
Kansas State University
Department of Chemistry
116 Cardwell Hall
Manhattan, KÍ 66506
Corwin@phys.ksu.edu
 
 
Mette Gaarde
Department of Physics and Astronomy
Louisiana State University
Baton Rouge, LA 70803-4001
gaarde@rouge.phys.lsu.edu
 
Dr. Richard Ell
77 Massachusetts Avenue
Massachusetts Institute of Technology
Cambridge, MA 02139
richard.ell@nanolayers.de
 
Mary Essary
FemtoLasers, Inc.
239 Stow Road
Harvard, MA 01451
mary.essary@femtolasers.com
 
Dr. William Graves
Bates Linac
M.I.T.
21 Manning Ave.
Middleton, MA 01949
wsgraves@mit.edu
 
Dr. Fatih O. Ilday
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge, MA 02141
ilday@mit.edu
 
Mr. Christian Jirauschek
Massachusetts Institute of Technology
Room 36-397
77 Massachusetts Avenue
Cambridge, MA 02139
jirau@mit.edu
 
Mr. Jung-Won Kim
Massachusetts Institute of Technology
Room 36-389, 77 Massachusetts Ave.
Cambridge, MA 02139-4307
jungwon@mit.edu
 
Prof. Daniel Kleppner
M.I.T.
Physics Department
77 Massachusetts Avenue
Cambridge, MA 02139
kleppner@mit.edu
 
Prof. Ingolf Lindau
Stanford University
SSRL/SLAC, Bin 69
2575 Sand Hill Road
Menlo Park, CA
lindau@ssrl.slac.stanford.edu
 
Dr. Henrik Loos
BNL
NSLS, Building 725C
Upton, NY 11973
loos@bnl.gov
 
Dr. Oliver D. Muecke
Massachusetts Institute of Technology
77 Massachusetts Avenue
Cambridge, MA 02139
odmuecke@mit.edu
 
Dr. Olga Smirnova
Photonics Institute
Vienna Technical University
Gusshausstasse 27/387
Vienna, A-1040 Austria
olga.smirnova@tuwien.ac.at
 
Ms. Marlene Wickenhauser
Technical University of Vienna
Wiedner Hauptstrasse 8-10
Vienna, A-1040 Austria
wick@concord.itp.tuwien.ac.at

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Workshop Schedule

November 20, 2003, Thursday

Cinema, Hilles Library downstairs (all day)
   
 8:30-8:45 Welcome
   

Session E1: Physics of Electron Wave Packet Formation and Recollision in Atoms and Molecules

Chair: L. Di Mauro (Ohio State University and Brookhaven National Laboratory)
8:45-9:30 M. IVANOV (NRC, Ottawa, Canada): Strong field ionization in tunneling and multiphoton regimes: a tutorial [Abstract]
 9:30-10:00 R. DOERNER (University of Frankfurt, Germany) : Using correlated electrons to probe re-collision
10:00-10:30 D. RAYNER (NRC, Ottawa, Canada): Electron Wave Packets Formed by Ionization of Large Molecules ­ Learning from C60 [Abstract]
10:30-11:00 COFFEE BREAK
   

Session P1: Physics and Optimization of Femtosecond-Laser-Driven High-Order Harmonic Generation (HHG) in Atoms

Chair: K. Schafer (Louisiana State Univ., USA)
11:00-11:45 A. L'HUILLIER (Univ. Lund, Sweden): Physics of high-order harmonic generation. Application to attosecond pulse generation [Abstract]
11:45-12:15 K. MIDORIKAWA (RIKEN, Saitama, Japan): Absorption-limited high-harmonic generation in the XUV region [Abstract]
12:15-12:45 M. MURNANE (JILA, Boulder, USA): Multiphoton EUV photonics [Abstract]
12:45-14:15 LUNCH BREAK
   

Session P2: Attosecond Pulse Trains from HHG

Chair: U. Keller (ETH, Zurich, Switzerland)
14:15-14:45 I. WALMSLEY (Univ. Oxford, UK): Attosecond metrology [Abstract]
14:45-15:15 H.-G. MUELLER (FOM, Amsterdam, Netherlands): Angularly resolved attosecond photoelectron spectra
15:15-15:45 P. SALIERES (CEA, Saclay, France): Time-frequency analysis of attosecond pulse trains [Abstract]
15:45-16:15 COFFEE BREAK
16:15-16:45   G. TSAKIRIS (MPQ, Garching, Germany): Second-order autocorrelation measurement of attosecond pulse trains [Abstract]
   

Session P3: Attosecond Pulses from X-ray Free Electron Lasers?

Chair: T. Tschentscher (DESY, Hamburg, Germany)
16:45-17:15 J. B. HASTINGS (SLAC, Stanford, USA): Linear accelerator based X-ray sources: temporal and spatial coherence [Abstract]
17:15-17:45 D. E. MONCTON (MIT, Boston, USA): Beyond self-amplified spontaneous emission:prospects for a transform-limited FEL-based x-ray laser [Abstract]
17:45-18:00 S.R. LEONE (BERKELEY NATIONAL LAB): Attosecond production with Linac-based ultrafast X-ray sources
18:00-19:00 RECEPTION IN PERKIN LOBBY
 

November 21, 2003, Friday

Phillips Auditorium (all day)

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Session E2: Using Molecular Clocks

Chair: D.M. Jonas (University of Colorado)
8:30-9:00 A. V. SOKOLOV (Texas A&M Univ., College Station, USA): Single-cycle optical pulses produced by molecular modulation [Abstract]
9:00-9:30 H. NIIKURA (NRC, Ottawa, Canada): Timing electron wave packets with H2+ [Abstract]
9:30-10:00 C.D. LIN (Kansas State Univ., USA): Dissociation and Ionization Dynamics of H2 /D2 in Intense Laser Fields [Abstract]
10:00-10:30 D. ZEIDLER (NRC, Ottawa, Canada): Imaging the electronic and atomic structure of molecules [Abstract]
10:30-11:00 COFFEE BREAK
   

Session AC: Towards Attosecond Control: Generation, Full Control, and Complete Characterization of Few-Cycle Light

Chair: F. Kärtner (MIT, Boston, USA)
11:00-11:30 H. HUTCHINSON (RAL, Oxford, UK): Optical parametric chirped pulse amplification and its application in attosecond systems [Abstract]
11:30-12:00 S. T. CUNDIFF (JILA, Boulder, USA): Carrier Envelope Phase Stabilization of Modelocked Oscillators [Abstract]
12:00-12:30 A. BALTUSKA (Vienna Univ. Techn., Austria): Generation and phase control of intense few-cycle optical pulses [Abstract]
12:30-14:00 LUNCH BREAK
   

Session EP: Generation and Measurement of Single Attosecond Electron and Photon Pulses with Few-Cycle Laser Pulses

Chair: Philippe Balcou (ENSTA - Ecole Polytechnique)
14:00-14:45 T. BRABEC (Univ. Ottawa, Canada): Theory of the generation and measurement of single attosecond pulses (tutorial) [Abstract]
14:45-15:15 G. G. PAULUS (Texas A&M Univ. College Station, USA): Quantum optics with tailored single optical cycles [Abstract]
15:15-16:00 R. KIENBERGER (Vienna Univ. Techn., Austria): Single sub-fs soft-X-ray pulses: generation and measurement (tutorial) [Abstract]
16:00-16:30 COFFEE BREAK

Postdeadline Session
16:30-16:45 ZENGHU CHANG [Kansas State University]: Generation of soft x-ray supercontinuum and single attosecond pulse by polarization gating [Abstract]
16:45-17:00 N. NAUMOVA [FOCUS]: Efficient generation of isolated attosecond pulses via relativistic effects [Abstract]
17:00-17:15 V. YANOVSKY [FOCUS]: Toward high energy (Joule level) attosecond pulses [Abstract]
17:15-17:30 G. SHVETS [FOCUS]: Generation of ultra-high intensity few-cycle pulses using Raman backscattering in plasmas [Abstract]
17:30-17:45 J. NEES [FOCUS]: Experimental design for measurement of attosecond impulses produced by relativistic effects [Abstract]
17:45-18:00 S. MALINOVSKAYA [FOCUS]: Control of transitions with broadband pulse shaping[Abstract]
18:00-18:15 M. WICKENHAUSER [Technical University of Vienna]: Theory of time-resolved autoionization using attosecond pulses [Abstract]
18:15-18:30 VIENNA WORK
 

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November 22, 2003, Saturday

Phillips Auditorium (all day)
   

Session CE: Collision Experiments: Insight into Attosecond Dynamics

Chair: S. Leone (University of California, Berkeley)
8:30-9:00 J. ULLRICH (Max Planck Institute for Nuclear Physics, Heidelberg, Germany): The attosecond Heisenberg microscope [Abstract]
9:00-9:30 C. A. C.-DREISMANN (Techn. Univ. Berlin, Berlin): Attosecond protonic quantum entanglement in collision experiments with neutrons and electrons [Abstract]
9:30-10:00 L. COCKE (Kansas State Univ., USA): Molecular clocks: from ion collisions to ultrafast lasers [Abstract]
10:00-10:30 COFFEE BREAK
    

Session E3: Attosecond Spectroscopy of Vibrational Wave Packets

Chair: A. Weber (NIST, Boulder and NSF)
10:30-11:00 D. VILLENEUVE (NRC, Ottawa, Canada): Determining molecular orbitals from high harmonic spectra [Abstract]
11:00-11:30 M. LEIN (Max Planck Institute, Dresden, Germany): Imaging of molecular structure using the coherence of recolliding electrons [Abstract]
   

Session E4: Attosecond Spectroscopy of Nuclear Wave Packets

Chair: D. Habs (Univ. Munich, Germany)
11:30-12:00 N. MILOSEVIC (Vienna Univ. Techn., Austria / Univ. Ottawa, Canada): How to use lasers to image attosecond dynamics of nuclear processes [Abstract]
12:00-12:30 A. BANDRAUK (Univ. Sherbrooke, Canada): Muonic Molecules in Super-Intense Laser Fields- A Route to Laser Control of Nuclear Process [Abstract]
12:30-14:00 LUNCH

Session P4: Attosecond Spectroscopy of Electron Wave Packets

Chair: P. Bucksbaum (FOCUS Center, Univ. Michigan, Ann Arbor)
14:00-14:30 A. SCRINZI (Vienna Univ. Techn., Austria): Tracing inner-shell electron dynamics with X-ray-pump/VIS-probe spectroscopy [Abstract]
14:30-15:00 S. MUKAMEL (Univ. California, Irvine, USA): Probing molecular electronic and nuclear dynamics by nonlinear ultrafast X-ray spectoscropy [Abstract]
15:00-15:30 M. DRESCHER (Univ. Bielefeld, Germany): Attosecond inner-shell atomic spectroscopy [Abstract]
   Closing remarks

Abstracts

Baltuska

Bandrauk

Brabec

C.-Dreismann

 Chang
 

Cocke

Cundiff

Drescher

Hastings

 Hutchinson
 
Ivanov
Kienberger

Lein

 L'Huillier

Lin

Malinovskaya

Midorikawa

Milosevic

Moncton

Mukamel 
 Murnane

Naumova

Nees 

Niikura 

 Paulus

Rayner 
 Salières

Scrinzi 

 Shvets

 Sokolov

Tsakiris 

Ullrich 
 

 Villeneuve

 Walmsley

 Wickenhauser

Yanovsky 

 Zeidler
 

 Generation and Phase Control of Intense Few-Cycle Optical Pulses

A. Baltuska

Photonics Institute
Vienna University of Technology
Gusshausstrasse 27/387
A-1040 Vienna, Austria

Intense ultrashort waveforms of light that can be produced with an exactly predetermined electromagnetic field are essential in a number of applications of extreme nonlinear optics, most prominently in laser-driven sources of high-energy attosecond radiation. Field reproducibility in each laser shot requires stabilization of the carrier-envelope phase. The talk will present different schemes of phase-stable pulse amplification and identify constraints limiting the precision with which the phase can be maintained. We will compare the methods for active and passive carrier-envelope control and outline their implementation in both laser and optical parametric amplifiers. We will further address techniques based on XUV and electron emission from photoionized atoms of a noble gas, which are suitable as a feedback in a phase drift compensation loop and can also be used for determination of the actual value of the carrier-envelope phase.

 

Muonic Molecules in Super-Intense Laser Fields- A Route to Laser Control of Nuclear Process

A D Bandrauk*, S C Chelkowski,P B Corkum,

Universite de Sherbrooke and NRC
Ottawa, Canada
 
*Canada Research Chair in Computational Chemistry and Photonics

We study by numerical solutions of time-dependent Schroedinger equations in super-intense laser fields (I>10**21 W/cm2) ionization and dissociation of muonic molecular ions (ddu).We predict that bonds break by tunnelling through "bond softened" barriers at intensities I~10**22 W/cm2. Ionization of the muonic atomic fragments occurs at much higher intensity I~10**23 W/cm2 and that Charge Resonance Enhanced Ionization,CREI, characteristic of molecular ions in intense laser fields is negligible due to the high velocity of the dissociated fragments.It will be shown that the superintense field induces and controls "recollision" oif the deuteron with its neighbor u-atom thus triggering a controlled nuclear fusion with sub-cycle precision. The recollision time and energy are shown to concur with classical models of laser induced electron recollision, LIER, in atoms.

In particular recollision energies of 3 Up~200-500 keV,s ,where Up is the ponderomeotive energy of a deuterium,can be readily achieved with intensities of ~10**22 W/cm2 thus opening a new avenue for creating and controlling highly charged particles using molecules as precursors.for laser induced nuclear reactions.

 

Theory of the Generation and Measurement of Single Attosecond Pulses

Thomas Brabec

Center for Photonics Research
University of Ottawa
150 Louis Pasteur, Ottawa
Ontario, K1N6N5 Canada


Theoretical and experimental aspects of attosecond xuv-pulse generation and measurement will be reviewed. A couple of ideas to use attosecond pulses for measuring ultrafast dynamics in matter will be discussed.

 

Attosecond Protonic Quantum Entanglement in Collision Experiments
with Neutrons and Electrons

C. A. C.-Dreismann

Institute of Chemistry, Stranski Laboratory, Technical University of Berlin
Strasse des 17. Juni 112, D-10623 Berlin, Germany
E-mail:
dreismann@chem.tu-berlin.de



Several recent experiments on liquid and solid samples containing protons or deuterons show a striking anomaly, which is a shortfall in the intensity of energetic neutrons scattered by the protons, cf. [1-3]. E.g., neutrons colliding with water for just attoseconds (1 as = 10-18 s) will see a ratio of hydrogen to oxygen of roughly 1.5 to 1, instead of 2 to 1 corresponding to the chemical formula H2O [1,3]. These neutron Compton scattering (NCS) experiments were done at the ISIS neutron spallation facility,UK. Due to the large energy and momentum transfers applied, the duration of a neutron-proton scattering event, ts, is a fraction of a femtosecond (say, 50-500 as) which is extremely short compared to condensed-matter relaxation times.
Very recently [2,3] this effect has been confirmed using an independent method, electron-proton Compton scattering (ECS). ECS from a solid polymer showed the exact same shortfall in scattered electrons (with energy about 20-30 keV) from hydrogen nuclei, comparable to the shortfall of scattered neutrons in accompanying NCS experiments on the same polymer [2,3]. The similarity of the results is striking because the two projectiles interact with protons via fundamentally different forces ­ electromagnetic and strong.
Theoretical considerations suggest the presence of short-lived (attosecond) quantum entanglement, in which the quantum dynamics of the scattering protons and the surrounding electrons are all interlinked in such a way as to change the nature of the scattering results. Note also that the time window of NCS and ECS, ts, is equal to the characteristic time of "electron motion", so that the widely used Born-Oppenheimer approximation is not applicable here. Moreover, the neutron and electron probes break apart the chemical bonds in molecules, thus providing novel insights on elementary chemical reactions involving hydrogen at the attosecond scale.

[1] C. A. Chatzidimitriou-Dreismann, T. Abdul-Redah, R. M. F. Streffer, J. Mayers,
Phys. Rev. Lett. 79, 2839 (1997)
[2] C. A. Chatzidimitriou-Dreismann, M. Vos, C. Kleiner, T. Abdul-Redah, Phys. Rev.
Lett.
91, 057403 (2003)
[3] Cf. also Physics Today, section "Physics Update", p. 9, September 2003

Generation of Soft X-Ray Supercontinuum and
Single Attosecond Pulse by Polarization Gating


 Bing Shan, Shambhu Ghimire, Chun Wang, and Zenghu Chang

Physics Department
Kansas State University
Manhattan KS 66506

Abstract PDF

 Molecular Clocks: From Ion Collisions to Ultrafast Lasers

C.L.Cocke

Physics Department
Kansas State University
Manhattan, KS 66506

The entangled motion of electronic and vibrational wave packets launched by the extraction of electrons from small molecules can be used in several ways to probe the time dependence of the heavy particle motion which follows. I will discuss several experimental COLTRIMS results on molecules ranging from H2 to C2H2 which use the correlated ionic/electronic motion in some way to probe the motion of the vibrational wave packet. Three types of impulsive excitation will be considered: an ion collision, a single hard photon excitation and a short-laser-pulse excitation.

 

Carrier-Envelope Phase Stabilization of Modelocked Oscillators

Steven T. Cundiff

JILA/National Institute of Standards and Technology and
University of Colorado
Boulder, CO 80309-0440 USA

 

Recent results in carrier-envelope phase stabilization of modelocked oscillators will be presented. The simplest approach to carrier-envelope phase detection requires an optical spectrum that spans an octave to obtain interference between spectral extremes by a second-order nonlinear process. The generation of an octave spanning spectrum in a modelocked ti:sapphire laser, which removes the need for external broadening, will be presented together with characterization of the laser. The observation the carrier-envelope phase sensitivity of quantum interference control of injected photocurrents in semiconductors allows simplification of the detection process.

 

Attosecond Inner-Shell Atomic Spectroscopy

M. Drescher[1], M. Hentschel[2], R. Kienberger[2], M. Uiberacker[2],
V. Yakovlev[2], A. Scrinzi[2], Th. Westerwalbesloh[1], U. Kleineberg[1],
U. Heinzmann[1], F. Krausz[2,3]

[1] Fakultät für Physik, Universität Bielefeld,D-33615 Bielefeld, Germany
[2] Institut für Photonik, Technische Universität Wien, A-1040 Wien, Austria
[3] Max-Planck Institut für Quantenoptik, D-85748 Garching, Germany

The implementation of isolated soft-X-ray pulses with sub-fs duration from high harmonic generation with few cycle laser pulses now enables dynamical studies of ultrafast inner-shell phenomena on the relevant time scale. Photon energies near 100 eV permit access to the interior of the atomic electron shell while the distinct attosecond time-structure guarantees a quasi-instantaneous excitation. The subsequent relaxation of the highly excited atoms can hen be tracked in an X-ray-pump / laser-probe experiment where the wave packet of an escaping secondary electron is sampled with the field of a delayed intense laser pulse.

The technique was applied to study the Auger decay of krypton-3d vacancies following core-hole creation with 97 eV pulses. Interaction of the Auger electron wave packet with the laser field gives rise to sidebands in the electrons' kinetic energy spectrum. The delay-dependent sideband area yields the desired Auger decay curve with a 7.9 fs time constant.

Recent progress in the phase stabilization of the fundamental laser has further improved the quality of the soft X-ray pulses in terms ofduration, jitter and contrast. Time-resolved spectroscopy of atomic processes evolving within a few hundred attoseconds is now becoming feasible.

 Linear Accelerator Based X-Ray Sources: Temporal and Spatial Coherence

J. B. Hastings

SSRL
Stanford Linear Accelerator Center
Stanford, CA 94305

Storage ring based synchrotron radiation (SR) sources are now commonplace in the world with the USA (APS), Japan (Spring-8) and Europe (ESRF) each operating sources in the hard x-ray energy range for studies in the chemical, biological and materials sciences. They have recently been applied to time resolved diffraction on the scale of the photon pulse length ~100 ps. Photon beams with all the properties of SR but with pulse lengths of ~100fsec are now available from linear accelerator based sources, for example the Sub-Picosecond Pulse Source (SPPS) at the Stanford Linear accelerator Center (SLAC). X-ray free electron lasers providing unprecedented pulse intensities, full transverse coherence, and pulse lengths of ~ 100 fs. are operating in the 100nm wavelength range and are in various stages of planning to reach the 0.1 nm range. The FEL process and the unique properties of these sources will be discussed with an emphasis on control of the temporal properties and the production of transform limited sub-fs pulses.

 

Optical Parametric Chirped Pulse Amplification and Its Application in Attosecond Systems

1M.H.R. Hutchinson, P. Matousek, J.L. Collier, O. Chekhlov, I.N. Ross

1CCLRC Rutherford Appleton Laboratory
Chilton, Oxfordshire, OX11 0QX, UK

The exciting prospects for attosecond science are driving the development of sub-5fs source lasers towards pulse energies and repetition rates very much greater than the current 1mJ and 1kHz respectively. One approach is in the use of optical parametric chirped pulse amplifiers (OPCPA) which have excellent properties for high energy, bandwidth and repetition rate. These properties will be presented together with a brief review of the OPCPA programme at RAL which encompasses the development of both PW and compact high average and peak power (CHAPP) systems. In particular a scheme will be described for the generation of attosecond pulses.

Strong Field Ionization in Tunneling and Multiphoton Regimes: A Tutorial

Misha Ivanov

Femtosecond Program
NRC Canada
100 Sussex Dr, 2069
Ottawa Ontario K1A 0R6 Canada


In this tutorial I will review the basics of multiphoton ionization in strong laser fields. Firstly, I will discuss ionization of atoms in the conventional tunneling regime of small Keldysh parameter, including the shape of the electronic wavepacket as it emerges in the continuum. I will briefly describe semi-classical and quasi-classical methods of the theoretical description of the problem.

I will then discuss the "grey area" of the Keldysh parameter just above unity, where both tunneling and conventional multiphoton ionization mechanisms compete or cooperate. If time permits, I will also briefly address strong-field ionization of small and large molecules.

 Single Sub-fs Soft-X-ray Pulses: Generation and Measurement

R. Kienberger[1], M. Uiberacker[1], E. Goulielmakis[1], A.Baltu_ka[1], M. Drescher[2] and F. Krausz[1,3]

[ 1]Institut für Photonik
Technische Universität Wien
Gusshausstr. 27
A-1040 Wien, Austria
Phone: +43-1-58801-38735
Fax: +43-1-58801-38799
E-mail: kienberger@tuwien.ac.at

[2] Fakultät für Physik
Universität Bielefeld
D-33615 Bielefeld, Germany

[3]Max-Planck Institut für Quantenoptik
Hans-Kopfermann-Straße 1
D-85748 Garching, Germany

The generation of ever shorter pulses is a key to exploring the dynamic behavior of matter on ever shorter time scales. Over the past decade novel ultrafast optical technologies have pushed the duration of laser pulses close to its natural limit, to the wave cycle, which lasts somewhat longer than one femtosecond (1 fs = 10-15 s) in the visible spectral range. Time-resolved measurements with these pulses are able to trace atomic motion in molecules and related chemical processes. However, electronic dynamics inside atoms often evolve on an attosecond (1 as = 10-18 s) timescale and require sub-femtosecond pulses for capturing them.

Atoms exposed to a few oscillation cycles of intense visible or near-infrared light are able to emit a single electron and X-ray photon wavepacket of sub-femtosecond duration. Precise control of these sub-femtosecond wavepackets have recently been achieved by full control of the electromagnetic field in few-cycle light pulses.

These X-ray pulses together with the few-cycle (few-femtosecond) laser pulses used for their generation have opened the way to the development of a technique for attosecond sampling of electrons ejected from atoms or molecules. This is accomplished by probing electron emission with the oscillating electric field of the few-cycle laser pulse following excitation of the atom by the synchronized sub-femtosecond X-ray pulse. Sampling the emission of photo electrons in this manner allows time-resolved measurement of the X-ray pulse duration as well as of the laser field oscillations.

 Imaging of Molecular Structure Using the Coherence of Recolliding Electrons

Manfred Lein

Max Planck Institute for the Physics of Complex Systems
Noethnitzer Str. 38
Dresden, 01187 Germany

Electrons that recollide with the core during strong-field ionization are fully coherent waves. In analogy to traditional diffraction, these electrons can therefore be used to probe the structure of laser-driven molecules. Our calculations show that a diffraction pattern due to the molecular structure is observed in the angular distribution of the elastically scattered electrons. An interference pattern is also found in the spectrum of the emitted high harmonics.

In the case of the H2 molecule, the initial ionization launches a vibrational wave packet on the potential surface of the molecular ion, and the motion of this wave packet is probed by the recolliding electron. From simple classical arguments, the energy of a harmonic photon is determined by the travel time of the free electron. Therefore, different harmonics serve as probes at different times, enabling the measurement of the wave-packet position on a sub-femtosecond time scale. Furthermore, we show that the harmonic intensities are sensitive to the overlap between the moving vibrational wave packet and the vibrational ground state of the neutral molecule. This effect leads for example to a suppression of harmonics in H2 as compared to D2, and might become another useful tool in vibrational spectroscopy.

 Physics of High-Order Harmonic Generation
Application to Attosecond Pulse Generation

Anne L'Huillier

Department of Physics
Lund Institute of Technology
Box 118
S- 221 00 Lund, Sweden

High-order harmonic generation in gases has led to a fascinating application: the generation of attosecond pulses of light.

This presentation is a tutorial on the physics of high-order harmonic generation: history, single-atom physics, optimization and characterization of high-order harmonics, attosecond pulse generation.

The experimental effort in Lund towards the generation and measurement of attosecond pulse trains will also be presented.

 

Dissociation and Ionization Dynamics of H2 /D2 in Intense Laser Fields

C. D. Lin and X. M. Tong

Department of Physics
J. R. MacDonald Laboratory
Kanas State University
Manhattan, KS 66506 USA

The dissociation and ionization dynamics of H2 and D2 molecules in intense short laser pulses for peak intensity in the sequential and nonsequential double ionization region will be discussed. Issues related to the possibility and limitations of using the ionization dynamics to measure molecular clocks at sub-fs precision will be addressed.

 Control of Transitions by Broadband Pulse Shaping in Stimulated Raman Spectroscopy

S.A. Malinovskaya, P.R. Berman, and P.H. Bucksbaum

Michigan Center for Theoretical Physics
FOCUS Center and Department of Physics
University of Michigan
Ann Arbor, MI 48109
 
 

Abstract PDF

 Absorption-Limited High-Harmonic Generation in the XUV Region

Katsumi Midorikawa

Laser Technology Laboratory, RIKEN
Hirosawa 2-1,Wako, Saitama 351-0198, Japan

    We have investigated the energy scaling of high-order harmonics under the phase-matched condition using a long interaction length and a loosely focused pumping geometry. In those experiments, we have generated peak powers of 130 MW at 62.3 nm, 10 MW at 30 nm and 1 MW at 13 nm, assuming the same pulse width as the pump pulse of 25-35 fs. When we focus these harmonic pulses with appropriate multilayer mirrors, the focused intensity will attain to 1013-1014 W/cm2. This high intensity is expected to give rise to nonlinear optical phenomena in the XUV region.
    We have been developing XUV optics including a beam splitter and multilayer mirrors for application of high harmonics to nonlinear optics in the XUV region.

How to Use Lasers to Image Attosecond Dynamics of Nuclear Processes

N. Milosevic,* P. B. Corkum and T. Brabec

*Photonics Institute - Theory Group
Vienna University of Technology
Gusshaussstrasse 27/387
1040 Vienna, Austria

We identify a laser configuration in which attosecond electron wave packets are ionized, accelerated to multi-MeV energies, and refocused onto their parent ion. Magnetic focusing of the electron wave packets results in return currents comparable with large scale facilities. This technique opens an avenue towards imaging attosecond dynamics of nuclear processes.

 Beyond Self-Amplified Spontaneous Emission:
Prospects for a Transform-Limited FEL-Based X-ray Laser

D. E. Moncton

MIT/Argonne

Although x-ray sources based on FELs using the method of self-amplified spontaneous emission (SASE) produce beams with full transverse coherence, the longitudinal coherence of such beams is less than 1%. Nevertheless such beams have a peak brilliance some 10 orders of magnitude greater that the most brilliant conventional synchrotron sources, and produce pulses with temporal durations below 1 picosecond. Thus SASE-based sources have been advocated for construction at Stanford (the LCLS project) and in Germany (the DESY XFEL project). At MIT we are studying the prospects of achieving the ultimate goal of full transform-limited performance by using high harmonics of a Ti:sapphire laser as a seed. Although challenging in many respects, it now appears possible to conceptually design such a facility based on technology that is currently available, or could be expected in the very near future. Our concept is based on a superconducting linac with high enough pulse rates (>10kHz) to support 10-30 independent beamlines for users in the spectral range from 100nm to 0.1 nm, with a power/pulse approaching 1 mJ. Our goal is to exploit the trade-off between pulse length and bandwidth at the Heisenberg limit, and have pulse lengths ranging from below a femtosecond to as long as a picosecond with corresponding bandwidths from a few electron volts to a few milli electron volts.

 

Probing Molecular Electronic and Nuclear Dynamics by Nonlinear Ultrafast X-Ray Spectoscropy

Shaul Mukamel[A], Luke Campbell [A and B], Satoshi Tanaka [C]

[A] Department of Chemistry, University of California Irvine, Irvine, CA 92697-2025
[B] Advanced Light Source, Lawrence Berkeley National Laboratory
[C] College of Integrated Arts and Sciences, Osaka Prefecture University, Saka 599-8531, Japan

Abstract PDF

 

Multiphoton EUV Photonics

Emily Gibson, Ariel Paul, Nick Wagner, David Gaudiosi, Etienne Gagnon, Margaret Murnane, Henry Kapteyn

JILA, University of Colorado, Boulder, CO 80309-0440
Ph: (303) 492-7839, FAX: (303) 492-5235, murnane@jila.colorado.edu

Ivan P. Christov
Department of Physics, Sofia University, Sofia, Bulgaria

High harmonic generation (HHG) is a useful source of coherent light in the extreme ultraviolet (EUV) region of the spectrum. In HHG, an intense laser is focused into a gas, generating high harmonics that emerge as a coherent, low-divergence beam. However, both the conversion efficiency and the highest achievable photon energy have been limited to-date by the inability to phase-match the frequency conversion process at high ionization levels. Plasma-induced dispersion prevents the laser and the EUV light from propagating at the same speed, and since the higher harmonics are generated at higher laser intensities-after much of the gas has ionized-this limits the highest observed photon energies. Overcoming ionization-induced phase-mismatch has thus been a critical challenge to the further development of coherent EUV sources at wavelengths of interest to lithography, high-resolution imaging, site-specific spectroscopy and bio-microscopy.

In previous work, we demonstrated quasi-phase-matching (QPM) of HHG to energies approaching 180eV corresponding to ionization levels <10%.[1] This QPM technique uses a periodically-bulged hollow waveguide to modulate the HHG process, creating a periodic change in the intensity and phase of the driving laser, and allowing coherent buildup of signal even in the presence of phase-mismatch.

Here we show that QPM can extend HHG into the "water window" region of the spectrum (at 284eV) using Neon.[2] Previous work in Neon had only observed HHG with energy <240eV. Moreover, previous work observing water window light used Helium, which has a much smaller nonlinear susceptibility than Neon and thus generates significantly less flux. Thus, this work demonstrates that the application of novel NLO techniques to HHG promises a practical coherent "water-window" light source for biomicroscopy. We also observe the highest-ever HHG of 250eV in Argon. This compares with 100eV observed previously, and is clearly HHG from ions.[3] Our use of a gas-filled hollow waveguide to guide the laser beam prevents laser beam defocusing at high ionization levels. This would otherwise limit the peak laser intensity and prevent the observation of very high-order HHG from ions.

In our work, we focus 22fs duration, 800nm laser pulses, with an energy of 2.1mJ, into a 150µm diameter, 2.5cm long, hollow fiber filled with gas. The fibers were modulated with period 0.25mm.

Fig. 1 shows the harmonic emission from Argon. The spectrum extends up to energies of 250eV. Calculations show that at the laser intensity required to generate this photon energy, Argon is fully ionized. Therefore, the HHG from 150-250eV is emitted from ions. Fig. 2 shows harmonic emission from Ne through Boron (black) and Carbon (red) filters. The presence of sharp absorption edges confirms the accuracy of our energy calibration. The C edge at 284eV represents the highest harmonics ever observed in Neon gas and the highest harmonics that have been quasi-phase-matched.

These results collectively suggest that hollow waveguide QPM technique can be applied to HHG in fully-ionized gasses, and that phase-matching and laser beam defocusing issues are not a fundamental limitation for HHG. Since the scaling of the high-harmonic "cutoff" photon energy is linear with the intensity of the driving laser, these techniques will be useful for extending HHG to >keV.

Fig. 1: Harmonic emission from 5Torr of Argon from a modulated fiber. The fall off at lower energies is due to the Ag filters used to reject the laser light.

Fig. 2: Harmonic emission from 9Torr of Neon from a modulated fiber. Red curve, right axis: Ag filters and C, showing C edge at 284eV edge. Black curve, left axis: Ag and B filters to show Boron edge at 188eV.

References
1. Ariel Paul, Randy Bartels, Ivan Christov, Henry Kapteyn, Margaret Murnane, Sterling Backus, "Multiphoton photonics: quasi phase matching in the EUV", Nature 421, 51 (2003).
2. Emily A. Gibson, Ariel Paul, Nicholas Wagner, Ra'anan Tobey, Ivan P. Christov, David T. Attwood, Eric Gullikson, Andy Aquila, Margaret M. Murnane, and Henry C. Kapteyn, "Generation of coherent soft x-rays in the water window using quasi phase-matched harmonic generation", Science 302, 95 (2003).
3. Emily A. Gibson, Ariel Paul, Nicholas Wagner, Ra'anan Tobey, Ivan P. Christov, Margaret M. Murnane, and Henry C. Kapteyn, "Very High Order Harmonic Generation in Highly Ionized Argon", to be published in Physical Review Letters (2004)

 

Efficient Generation of Isolated Attosecond Pulses Via Relativistic Effects

N. Naumova, J. Nees, I. Sokolov*, B. Hou, E. Power,
A. Maksimchuk, V. Yanovsky, G. Mourou

Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109-2099
*Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143

We present a scheme for isolated attosecond pulse generation based on the relativistic motion of free electrons in overcritical-density targets. This result is predicted when few-cycle optical pulses are focused to wavelength dimensions on a wavelength-scale-length overdense plasma profile. Under these conditions which we dub the relativistic lambda cubed regime, a millijoule of optical energy can simultaneously provide relativistic intensity and maximal field gradients. Because the relativistic intensity beam is focused to one wavelength, the light pressure from each half cycle shapes on the critical surface a "single mode concave mirror" that oscillates at twice the laser frequency. Under certain conditions of plasma density, we found with particle-in-cell (PIC) simulations that this mirror can, at each cycle, simultaneously relativistically compress and deflect the electromagnetic wave, providing isolated attosecond pulses. This technique which is intrinsically efficient (because it uses a critical surface reflection) can be scaled to much higher energies in the joule range and, maybe in the future to the kilojoule range, by simply adjusting the plasma density.

 Experimental Design for Measurement of Attosecond Impulses
Produced by Relativistic Effects

E. Power, J. Nees, , S.-W. Bahk, B. Hou, V. Yanovsky, N. Naumova, G. Mourou

Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109-2099

Presently, attosecond pulse measurements are made using electron ionization. We propose a simple autocorrelator design that would enable measurement of electromagnetic pulses down to 250 attoseconds in a poor-vacuum environment. In this arrangement pulses generated by relativistic effects in a pinpoint source are collected by split mirror and collimated by a metallic paraboloid, then redirected to a wide-bandgap photoconductive detector. The resulting multi-photon signal is collected as a function of delay obtained by longitudinally scanning one segment of the split mirror, as in conventional two-photon autocorrelators. Ultimately the refocusing of such radiation could result in focused intensity as high as the initial driving radiation. The limits of the optical components and distortions will be discussed.

 Timing Electron Wave packets with H2+

Hiromichi Niikura, F. Légaré, M. Yu. Ivanov, D. M. Villeneuve and P. B. Corkum

National Research Council of Canada
100 Sussex Dr. Ottawa, Ontario K1A 0R6 Canada

During ionization by an intense laser pulse (~1014W/cm2), the newly ionized electron is first pulled away from the parent ion and driven back after the field reverses. The electron-ion re-collision process occurs with attosecond timing precision. We use the H+ vibrational wave packet motion as a 'clock' to measure the dynamics of the re-colliding electron. Tunnel ionization of H2 by intense laser fields produces both electron and vibrational wave packet of H2+ simultaneously at around peak of laser fields. Until the electron returns to the parent ion, the vibrational wave packet moves on H2+(Sg) surface. When the electron re-collides, inelastic scattering excites (or further ionizes) H2+ leading to the energetic fragmentation. The kinetic energy spectrum of H+ is a measure of the position of the vibrational wave packet at the time of re-collision and therefore a measure of the time delay between ionization and re-collision. Using this procedure, we observed that the re-colliding electron consists of a decaying series of micro-"bunches", with the first micro-bunch containing 50% of the charge and each micro-bunch having duration ~ 1fs and separated by ~ 1.5 femtoseconds (1/2 laser period). We also demonstrate that few-cycle-laser pulses can eliminate the second and third re-collision.

The re-colliding electron can be used to probe molecular dynamics in the parent molecule with attosecond time resolution. Changing the laser wavelength changes the time delay between ionization and re-collision. From the kinetic energy distribution of D+ at four different laser wavelengths from 800 nm to 1850 nm, (corresponding time delay is ~1.7 fs ­ 4.5 fs), we observed the D2+ wave packet motion with an accuracy of 200 attosecond and 0.05 Angstrom.

References
H. Niikura et al, Nature 417, 917-922 (2002)
H. Niikura et al, Nature 421, 826-829 (2003).

 

Quantum Optics with Tailored Single Optical Cycles

G. G. Paulus

Dept. of Physics
Texas A&M University
College Station, TX 77843

Abstract PDF

 Electron Wave Packets Formed by Ionization of Large Molecules ­ Learning from C60

David Rayner

Steacie Institute for Molecular Sciences
National Research Council
100 Sussex Drive
Ottawa, Ontario K1V 7E6
david.rayner@nrc.ca

We show how the many electron response of a complex molecule to an intense laser pulse can be incorporated into the single active electron picture. This allows us to introduce a model for C60z+ ionization, valid for long wavelength light. In confirming the model we produce C6012+, the highest charge state observed to date. The model also lets us address the role of electron recollision in large, highly polarizable molecules. In C60, we identify recollision through the fragmentation it produces in intermediate charge states. From the elipticity dependence we find that the ionizing electron emerges from C60z+ (z = 3, 4) with a lateral velocity of ~12 °A/fs, approximately half its Fermi velocity. Despite the large lateral velocity and competing forces on the electron, recollision remains relatively probable for this scale of molecule. At high intensities and charge states the stress on the molecule due to the laser-induced dipole force (related to bond-softening in small molecules) and rapid charging leads to delayed fragmentation. The interplay between the two processes will allow us to control the internal energy of molecules.

 

Time-Frequency Analysis of Attosecond Pulse Trains

Y. Mairesse1, A. de Bohan1, L.J. Frasinski2, H. Merdji1, L.C. Dinu3, P. Monchicourt1, P. Breger1, M. Kovacev1, B. Carré1, H.G. Muller3, P. Agostini1 and P. Salières1

1Commissariat à l'Energie Atomique, DRECAM/SPAM, Centre d'Etudes de Saclay, 91191 Gif-sur-Yvette, France
2The University of Reading, J. J. Thomson Physical Laboratory, Whiteknights, PO Box 220 Reading RG6 6AF, United Kingdom
3FOM Institut for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands

Attosecond pulse trains can be obtained by superposing several high harmonics of an intense laser pulse [1]. Provided that the harmonics are emitted simultaneously, increasing their number should result in shorter pulses. However, by measuring the relative phase of harmonics over a large spectral range, we demonstrate that the high harmonics are not synchronised on an attosecond timescale, thus setting a lower limit to the achievable X-ray pulse duration [2]. We show that the synchronisation can be improved considerably by controlling the underlying ultra-fast electron dynamics, to provide pulses of 130 attoseconds in duration. We discuss the possibility of achieving even shorter pulses, that would allow us to track the fastest electron processes in matter.

[1] Paul et al., Science 292, 1689 (2001)
[2] Mairesse et al., Science, in press.

Tracing Inner-Shell Electron Dynamics with X-Ray-Pump/VIS-Probe
Spectroscopy

Armin Scrinzi

Photonics Institute
Vienna University of Technology
Gusshausstrasse 27/387
A-1040 Vienna Austria/EU
e-mail: scrinzi@tuwien.ac.at

A quantum theory for the XUV-attosecond pump and laser probe measurement of an
Auger decay will be laid out, which describes the key features of this type of experiments in the quasi-classical and side-band regimes. It is found that quantum coherence between corehole formation and Auger decay can lead to observable effects in the Auger spectrum. Based on this complete analysis a general recipe for constructing laser assisted spectral amplitudes from field-free amplitudes will be proposed. It will be discussed, to which extent the field-free relaxation dynamics can be reconstructed from a pump-probe measurements.

 

Generation of Ultra-High Intensity Few-Cycle Pulses Using Raman Backscattering in Plasmas

G. Shvets

Illinois Institute of Technology
Chicago, IL 60616
gena@fnal.gov

Abstract PDF

 

Single-Cycle Optical Pulses Produced by Molecular Modulation

A. V. Sokolov

Department of Physics and Institute for Quantum Studies, Texas A&M University, College Station, TX 77843-4242, U. S. A.
Phone: (979) 845-8519, FAX: (979) 458-1235, E-mail: sokol@jewel.tamu.edu

We have recently demonstrated that coherent molecular motion can result in a collinear generation of equidistant mutually-coherent spectral sidebands, extending in frequency from infrared to far ultraviolet. Our technique is based on adiabatic (electromagnetically induced transparency - like) preparation of maximal molecular coherence, which is achieved by using two narrow-linewidth lasers slightly detuned from a Raman resonance. The phases of the resultant Stokes and anti-Stokes sidebands are then adjusted in order to synthesize desired single-cycle waveforms at the target [A.V. Sokolov and S. E. Harris, J. Opt. B 5, R1, 2003]. By the very nature of the generation process, this light source produces trains of pulses, which are perfectly synchronized with the molecular motion in the given molecular system and provide a unique tool for studying molecular and electronic dynamics. We envision producing a coherent molecular oscillation, applying a tightly focused train of perfectly timed pulses, adjusting the delay, and studying electronic properties as functions of molecular coordinates. In the future, this Raman source may also produce sub-cycle optical pulses, and allow synthesis of waveforms where the electric field is a predetermined function of time, not limited to quasi-sinusoidal oscillations. As a result, a direct and precise control of electron trajectories in photoionization and high-order harmonic generation will become possible. A particularly intriguing, even if speculative possibility is to use an ultra-strong non-sinusoidal field to control the motion and collisions of nuclei that originate from molecular photoionization.

 Second-Order Autocorrelation Measurement of Attosecond Pulse Trains


P. Tzallas*, D. CharalambidisÝ, N. A. PapadogiannisÝ, K. Witte*, G. D. Tsakiris*

* Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany.
Ý Foundation for Research and Technology - Hellas, Institute of Electronic Structure & Laser,
PO Box 1527, GR-711 10 Heraklion (Crete), Greece and
Department of Physics, University of Crete, P.O. Box 2208, GR-71003 Voutes-Heraklion (Crete), Greece

In pico- and femtosecond laser laboratories, the pulse duration has been for many years routinely extracted to a satisfactory degree of accuracy from a measurement of the second-order AC trace. This most widely used method relies on a non-linear effect induced solely by the radiation to be characterized. The extension of the approach to sub-femtosecond XUV pulses poses several formidable problems since attosecond pulses are spectrally much broader and in the nearly inaccessible UV-XUV spectral range and orders of magnitude weaker, thus requiring ultra-sensitive non-linear detectors with a flat broadband response. Employing appropriate modifications, we have succeeded in surmounting these obstacles and demonstrating the applicability of this non-linear technique to the broadband radiation of a coherent superposition of harmonics and thus to the attosecond regime [1]. While the unique capabilities of this new approach are demonstrated here in performing the first AC measurement of an attosecond pulse train, the method itself initiates the XUV-pump ­ XUV-probe studies in sub-femtosecond scale dynamics. The key factors are (i) the technique of the dispersionless volume auto-correlation and (ii) the demonstration of the two-photon non-resonant ionisation process in helium as an appropriate detector with adequately flat response [2,3]. The experimental results bear direct evidence that a synthesis of five harmonics (7th to 15th) produced in a Xe gas jet gives rise to an XUV signal exhibiting clear attosecond structure with periodicity twice that of the driving laser field. Within the accuracy limitations of the second-order AC technique, a simple deconvolution procedure gives an average duration for the attosecond peaks, which is more than double the Fourier transform-limited value. The possible reasons for this discrepancy will be discussed.

This work is supported in part by the European Community's Human Potential Programmes Generation and Characterisation of Attosecond Pulses in Strong Laser-Atom Interactions: A Step towards Attophysics (ATTO) and the Ultraviolet Laser Facility (ULF).
References
[1] P. Tzallas et al., Nature (2003), in press
[2] N. A. Papadogiannis, et al. Phys. Rev. Lett. 90, 133902 (2003).
[3] N. A. Papadogiannis, et al. Appl. Phys. B 76, 721-727 (2003).

 The Attosecond Heisenberg-Microscope

Joachim Ullrich

Max-Planck-Institut für Kernphysik
D-69117 Heidelberg, Germany

Highly-charged ions at velocities close to the speed of light generate extremely strong (I = 1015 ­ 1021 W/cm2), ultra-short (t = 10-19 - 10-17 s) electromagnetic (half-cycle) pulses when passing target atoms, molecules or clusters at large impact parameters far outside the respective electron clouds. Depending on the strength of the field (proportional to q/vp with q the charge state and vP the velocity of the ion) and the magnitude of the momentum transfer in the collision, the interaction with the target can be interpreted in terms of the scattering of virtual photons (Compton scattering), the absorption of one (Bethe-Born approximation) or the simultaneous, incoherent absorption of "many" virtual photons (Weizsäcker-Williams method of equivalent photons). Kinematically complete experiments where the momenta of all emerging fragments are determined at various field strength (q/vP) provide the key to identify all of the above processes. The simultaneous emission of many electrons by "simultaneous" (within less than attoseconds) absorption of many virtual photons might open the unique possibility to "image" the correlated motion of electrons in ground states of atoms, molecules and clusters on a time-scale not accessible by any other method. In first experiments (GSI, Darmstadt), strong correlation between the emitted electrons in the continuum is found for double and triple ionization by means of intensity interferometry and using Dalitz-plots. Evidence is provided that the observed patterns are indeed due to the ground state correlation.

 Determining Molecular Orbitals from High Harmonic Spectra

D M Villeneuve, Jiro Itatani, Jerome Levesque, Dirk Zeidler and Paul Corkum

Steacie Institute for Molecular Sciences
National Research Council of Canada
100 Sussex Drive
Ottawa Ont. K1A 0R6 Canada

High harmonic emission from aligned molecules is due to the oscillating dipole induced in the HOMO orbital by the ionized electron. The spectrum contains a number of Fourier components of spatial projections of the wave function. By recording spectra at a number of molecular orientations, it is possible to determine the shape of the original electronic orbital.

 

Attosecond Metrology

Ian A. Walmsley

Clarendon Laboratory, University of Oxford, Parks Rd., Oxford OX1 3PU, UK
Phone: +44 1865 272 205. FAX: +44 1865 272 375. Email: walmsley@physics.ox.ac.uk

Abstract
Recent advances in the generation of attosecond-duration electromagnetic pulses demand the development of methods to measure them. The combination of sources and measurement technology provides an important set of tools for the study of electron dynamics in matter of all kinds. I survey several recent proposals for attoseconds metrology, and compare their efficacy and range of applicability.

Summary
The ability to measure ultrashort optical pulses has had a major impact in ultrafast nonlinear spectroscopy. The electromagnetic field is the fundamental entity of the interaction of light with matter, and the most information about that interaction is available in the spatio-temporal field of the scattered radiation. For this reason, it is preferable in many experiments to measure the pulse field rather than the transmitted energy or even the temporal intensity.
Extending metrologic capability into the attosecond domain [1-3] is not a simple modification of methods suitable for the visible and near-infrared regimes, primarily because of the very short wavelengths needed to synthesize attoseconds pulses, and the small pulse energies that are available from current laser-based sources.

The primary requirements for measuring pulses with duration very much shorter than the response times of available photodetectors are a set of filters, at least one of which should have time nonstationary response function and another a time-stationary response. In the past decade several robust and reliable methods for characterizing the temporal structure of ultrafast optical pulses have been demonstrated, primarily based on spectrography and self-referencing interferometry. In spectrography, the spectrum of a pulse that has been temporally "sliced" out of the original pulse is measured for intervals that range across the entire extent of the pulse. The most well known of this class of techniques is frequency-resolved optical gating, or FROG.[4]

Self-referencing interferometry, on the other hand involves the mixing of two fields that are replicas of each other except that one of the replicas is shifted: in space or wave vector for the measurement of spatial wave fronts, in time or frequency for the measurement of pulse temporal profiles.[5] The coincidence of these fields on a square-law detector allows one to read the phase difference between the shifted replicas in the intensity pattern. The shifting of one of the replicas requires a system with either a space-shift or time-shift variant response function, depending on whether one is measuring spatial or temporal phase. This is the idea behind spectral phase interferometry for direct electric field reconstruction, or SPIDER, for which the spectral phase of a pulse is estimated from the interference of two spectrally sheared replicas.

The usual sorts of nonlinear optical processes that provide the necessary filters in the optical regime are not operative in the XUV regime. In fact, in such a regime almost any interaction with matter will cause ionization, and one route to attosecond-pulse metrology is to develop this into a nonlinear response by the simultaneous absorption of a second photon.[3] This is possible when the electron has not moved significantly from the ionic core, provides a suitable nonlinear, nonstationary mechanism that can be applied to pulse characterization. The large bandwidth of coupling to the continuum means that this class of nonlinearities is capable of responding to extremely short pulses with wavelength ranges into the XUV and even X-ray regimes. The photoelectron number and energy spectrum both contain information about the duration of the XUV pulse. Indeed arrangements exist by which the photoelectron spectrum contains sufficient information to completely reconstruct the XUV pulse field in a single shot.

An alternate route is to engineer the source of attosecond radiation to generate sets of pulses that can be used to characterize the emission directly in the XUV domain. This route has the advantage of a much larger signal to noise ratio, and indeed sufficient signal that single-shot capability is possible. Given the sensitivity of attosecond pulse shapes to the shape of the driving pulse in a high-harmonic configuration, this is both an important feature and a serious limitation to the measurement of individual attosecond duration electromagnetic fields.

References

1. M. Hentschel et al., Nature, 414, 509 (2001)
2. M. Drescher et al., Science 291, 1923 (2001)
3. P. M. Paul et al., Science 292, 1689 (2001); H. G. Muller, to appear in Applied Physics B
4. R. Trebino et al., Rev, Sci. Instr., 68, 3277-3295 (1997)
5. C. Iaconis and I. Walmsley, Opt. Lett. 23, 792-794 (1998); IEEE Journal of Quantum Electronics, 35, 501-509 (1999).

 

Theory of Time-Resolved Autoionization using Attosecond Pulses

M. Wickenhauser,[1] J. Burgdörfer,[1] F. Krausz,[2] and M. Drescher [3]


[1]Inst. for Theoretical Physics, Vienna University of Technology, A-1040 Vienna, Austria

[2]Inst. for Photonics, Vienna University of Technology, A-1040 Vienna, Austria

[3]Faculty of Physics, University of Bielefeld, D-33615, Germany

 

Abstract PDF

 

Toward High Energy (Joule Level) Attosecond Pulses

V. Yanovsky , S. Bahk, A. Maksimchuk, , V. Chvykov, G. Kalinchenko, and G. Mourou

Center for Ultrafast Optical Sciences
University of Michigan
1006 I ST 2200 Bonisteel Blvd.
Ann Arbor, Michigan 48109-2099

Recent simulations (Naumova et al'2003) showed that reflection of sharply focused (focused into a wavelength limited spot) laser light leads to attosecond pulse generation due to critical surface dynamics. We discuss possibility of generating high energy (Joule scale) attosecond pulse using this effect. In addition, we experimentally demonstrate focusing of 30TW pulse into a wavelength limited spot.

A fast (f/1) paraboloid aberrations were corrected by a deformable mirror to produce the fully characterized intensity exceeding 1021W/cm2. Our characterization method provides for the first time the amplitude and phase of this ultra relativistic pulse over the whole focal volume.

 Imaging the Electronic and Atomic Structure of Molecules

D. Zeidler[1], I. Litvinyuk[1], J. Itatani[1], D. Comtois[1,2], J. Levesque[1,2], K. Lee[1,3], P. Dooley[1,3]
J-C. Kieffer[2], H. Pepin[2], D. Villeneuve[1] and P. B. Corkum[1]

[1]National Research Council of Canada, Ottawa, Ont. Canada
[2]INRS, University of Quebec, Varennes, P.Q. Canada
[3]McMaster University, Hamilton, Ont. Canada

The same re-collision electrons that are responsible for high harmonics and attosecond pulses are used to measure molecular structure. We measure the lateral momentum of the elastically scattered electrons, observing laser induced electron diffraction from N2. In N2 and O2, we measure the structure of the harmonic plateau, observing the symmetry of the electron state from which the re-collision originated. Measurements that combine attosecond time resolution and Angstrom spatial resolution are now possible for a wide class of small molecules.

 

 

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ACCOMMODATIONS

Listed below are the names and, where possible, the 800 numbers of hotels and a bed and breakfast agent to assist you in getting accommodations for the upcoming Workshop.

It is especially important that you book a room for the workshop right away as the fall is a very busy time in Cambridge, and you might not be able to get one of the cheaper bed and breakfasts. As housing is expensive in Cambridge/Boston, you may wish to get together with a friend and share a room.

The hotels are within walking distance of the Institute, the Sheraton a short walk and the other two longish walks. They all are on bus routes:

Best Western Homestead Inn, 220 Alewife Brook Parkway, Cambridge,
MA 02138; (617) 491-1890 or 1 (800) 528-1234

Harvard Manor House, 110 Mt. Auburn St., Cambridge, MA 02138
(617) 864-5200

Sheraton-Commander, 16 Garden St., Cambridge, MA 02138; (617) 547-4800 or 1 (800) 325-3434

Boston Reservations/Boston Bed & Breakfast, Inc., 1643 Beacon St., Suite
23, Waban, MA 02168; (617) 332-4199; Fax: (617) 332-5751; e-mail: bostonreservations@bostonreservations.com

All of this information plus more is on the ITAMP web page at http://www.cfa.harvard.edu/itamp under "living accommodations."

We recommend your booking through Boston Reservations/Boston Bed & Breakfast, as in most cases they can get you a room at lower cost than a cold call will get you. If you tell them you are attending a workshop at the Harvard Observatory, they will make every effort to book you at a bed and breakfast, or hotel if you wish, in close proximity. They have many comfortable accommodations in the surrounding neighborhood, and previous workshop participants have been very satisfied with their rooms.

We also strongly advise your not bringing or renting a car. There is no visitor parking at the Observatory and most on-street parking in Cambridge is designated for Cambridge residents only. There are few places in Cambridge and Boston that aren't easily accessible by public transportation and we recommend it highly.
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