Enlightened by lasersQ. Charles Su

Intense Laser Physics Theory UnitIllinois State University

CAS Lecture 2006 Illinois State University April 25, 2006

SupportNational Science Foundation

US Department of EnergyResearch Corporation

College of Arts & SciencesDepartment of Physics

LightNewton, Edison (1879) lights up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

In the beginning there was no light …

fire makes us happy

IN THE BEGINNING - (c 4.5 Billion BC)THE SUN - (c 4 Billion BC)THE EARTH - (c 4 Billion BC)EARLY LIFE - (c 3 Billion BC)PHOTOSYNTHESIS - (c 2 Billion BC)FIRST MAN - (c 1 Million BC)EARLY MAN - (c 500,000 BC)FIRE, FLAME and TORCH - (c 400,000 BC)PRIMITIVE LAMPS - (c 13,000 BC)ANIMAL LAMPS - (c 5000 BC)EARLY LIGHTING - (3000 BC)SUNDIAL - (c 1500 BC)OIL POTTERY LAMPS - GREEK - (600 BC)OIL RESERVOIR LAMP - (500 BC)ROMAN - LIFE & LIGHT - (400 BC - 80 AD)COLOR AND MUSIC (SOUND) - (c 350 BC)EARLY OPTICS & LENSES - (c 300 BC)HORN LANTERN - (c 100 AD)CANDLE - (c 400)CAMERA OBSCURA - (c 1000)COLORS OF THE SPECTRUM - (1666)POLARIZATION/POLARIZED LIGHT - (1678)PHOTOGRAPHY, EARLY - (1727)ADDITIVE COLOR MIXING - (1769)BETTY LAMP (& BETSY LAMP) - (1790)FIRST - GAS LIGHTING - (1792)INFRARED - (c 1800)

ULTRAVIOLET LIGHT (UV) - (1801) ELECTRIC ARC LIGHT/ CARBON ARC LIGHT - (1809)PHOTOGRAPHY, MODERN - (1826)SPEED OF LIGHT - (1849)SPECTROSCOPE - (c 1850) KEROSENE LAMP - (1853)FIRST - FOLLOWSPOT SPOTLIGHT - (c 1856)PHOTOGRAPHY, MOTION PICTURES - EARLY - (1872)FIRST - ELECTRIC FILAMENT (INCANDESCENT) LAMP - (1874)EDISON LAMP - (1879) SWAN LAMP - (1879)FIRST - PHOTOCELL - (1880)ELECTRICITY - (1899)HIGH INTENSITY DISCHARGE (HID) LAMP - (1901)MERCURY-VAPOR LAMP - (1901)TUNGSTEN FILAMENT LAMP - (1907)GAS FILLED LAMP - (1913)FLASHBULB - (1930)SODIUM LAMP - (LOW PRESSURE) - (1932)FLUORESCENT LAMP - (1937)PHOTOGRAPHY - POLAROID CAMERA - (1947)FIBER OPTICS - (1955)LASER - (1960)HOLOGRAM/HOLOGRAPHY - (a 1960)QUARTZ HALOGEN LAMP - (1960)LIGHT EMITTING DIODE - (a 1965)

A very brief history of light

wave theory

corpuscular theory

Christiaan Huygens1629–1695

James Clerk Maxwell1831–1879

Sir Isaac Newton1643 –1727

Electromagnetic waves

Albert Einstein 1879–1955

photons

Theories of light

laying of the mains and installation of the world's first permanent, commercial centralpower system in lower Manhattan, which became operative in September 1882.

Edison practically lit up the world

LightNewton, Edison lights (1879) up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

Laser usagesprecision

CD playerscannerprinter

powercutting, laser surgery

temporal precisionprobe fast processes

high temperaturefusionphotodynamic therapy

cheaper / safer imagingphoto density waves

In the movies

Laser shows

LightNewton, Edison lights (1879) up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

Active medium (hurdles in a stadium)

Hurdles ~ Atoms

Hurdle in up position~ population inversion

Hurdle reset after fall down~ external “pumping”

A hurdle goes down, energy releases, a pigeon flies away

pigeon ~ photon

down randomly~ spontaneous emission of light

After many hurdles are down …

No laser

Now a pigeon with the right energy knocks down a hurdle…

+ = hurdle is down +

2 pigeons fly off exactly the same way

~ stimulated emission of light (Einstein)

2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384 32768

… (after 29 rounds) 536,870,912 > US population… (after 33 rounds) 8,589,934,592 > world population

all in concert with each other

~ light amplification

Start with one pigeon

Let pigeons turn around in the stadium and work hard…

Then open up the stadium gate from time to time~ Light Amplification by Stimulated Emission of Radiation

Ingredients of a laser(1) Active medium with population inversion(2) Stimulated emission(3) Light amplification with resonator

LightNewton, Edison lights (1879) up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

Laser laboratories and how they are related to my research

Lab for Laser Energetics (U. Rochester)Laser fusion experiments Diagnostics temperature and density determinations x-ray imagingISU-UR collaboration through the DOE NLUF grants

Intense laser facilities around the worldSaclay-France FOM-Holland MPQ-Germany Lund-SwedenSIOFM-China U Tokyo-Japan QOLS-UK URC-CanadaATT BrookHaven U Michigan LLLISU: Numerical/Gedanken experiments

Ultra relativistic laser experiments planedDESY, Hamburg GSI-DarmstadtSLAC-Stanford CUOS-Ann ArborISU: Computer simulations, NSF grants

Bio-optical imaging researchLabs: U Penn, UC Irvine, U Mass, UIISU: light scattering lab and MC computations

Modeling laser action on computers

Physics andequations

Computerprogramming

Simulations ofexperiments

Result visualization Explanation More simulations

Great space for (undergraduate) student involvement

ˆ b p(t) ˆ b p' p U(t) p' p' ˆ d n'

p U(t) n'n'

ˆ d n(t) ˆ b p' n U(t) p'

p' ˆ d n'

n U(t) n'n'

ˆ b p(t)Wp(x) p ˆ d n

(t)Wn(x)nx,t̂

U(t)=T exp{–i∫0t dt’ [c·p–·A(x,t’)+c2+V(x,t’)]}

Laboratory experiments guide theoryMultiphoton ionization 1960sAbove threshold ionization 1979–Higher order harmonic generation 1980s

Computer experiments predict new physics?Atomic stabilization 1990 Cycloatom 2000Klein paradox 2004Bioimaging 2005

Fishing or cleaning fish ?

Laser atom

+–

+ –+

–

Laser-atom interaction

A microscopic view

Outcome 1: bound Outcome 2: ionized

How does ionization vary with laser intensity ?QuickTime™ and a

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V(x) 1/ 1 x2

J. Javanainen, J.H. Eberly and Q. SuPhys. Rev. A 38, 3430 (1988)

Computer simulation of atomic ionization

Pick a laser intensity I

Model atom (Rochester model)

Interaction with laser

Solve: Schrödinger equation

Compute ionization for each state

Current QM state future state

Gedanken experiment on computer:Ionization beyond 1016 W/cm2

ionization

100%

0 laser intensity

?IN

weak

all ionized

strong

superstrong

10–6

10–4

LASER

INTENSITY

P(t)

P(t)

P(t)

P(t)

P(t)

P(t)

P(t)

P(t)

I1

I3

I2

I4

I4

I5

I6

I7

Su, Eberly, Javanainen PRL, 64, 862, ’90

10 -1

10 0

10 -2 10 0 10 2

P(T,

I)

I (a.u.)

1st recovery

2nd3rd

Ioni

zati

on P

(T)

Laser intensity, I

123

4 56

7

Ionization Suppression!

I > 1016 W/cm2

Electron spatial density

Su, Laser Phys. 3, 241 (1993)Gavrila, Atoms in Intense Fields (1992)

Las

er in

tens

ity

space0

atom Outcome 1: bound + –

stabilization+ –Outcome 3:

stabilized

ionization+

–Outcome 2:

ionized

Computer prediction: Stabilization

NormallyIncreased intensity increases ionizationmore chance for electron to pick up energy around nucleus

At super-strong fieldsLaser also distorts electron orbitsreduces the chance of interaction with nucleus

Other theoretical studies and experimental evidenceKulander et al, Atoms in Intense Laser Fields Ed Gavrila, (1992)Keitel and Knight, Phys. Rev. A 51,1420 (1995)van Druten, et al Phys. Rev. A 55 622(1997)Longhi, et al, Phys. Rev. Lett. 94, 073002 (2005)

+ –

+ –

10 -1

10 0

10 -2 10 0 10 2

P(T

, I)

I (a.u.)

1st recovery

2nd3rd

n = S

S

Stabilization and recoveries of ionization

Su, Irving*, Johnson*, Eberly, J. Phys. B 29, 5755 (1996)Su, Irving*, Eberly, Laser Phys. 7, 568 (1997)

> 128 groups in 23 countries

Users of the Rochester model atom

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LightNewton, Edison lights (1879) up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

safer than x-ray CTcheaper than MRIbetter resolved than ultrasound

Dream: to build an imaging device …

Possible solution: IR laser based imaging

Imaging schemes

shadowx-ray

shadow-gram (like x-ray, CAT)

reflection-gram (like ultra-sound)

scatter-gram (infrared lasers)

ultra-sound

laser

medium —> scattered light

medium <— scattered light

Forward problems (predict the future)

Inverse problems (predict the past)

Light-medium interaction computer simulations

Pane of glass Random medium

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FFT on the grid method Wanare, Su and Grobe, PRE 62, 8705 (2000)

X-rays vs laser light

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Monte Carlo Simulation S. L. Jacques and L.-H. Wang, in Optical Thermal Response of Laser Irradiated Tissue, edited by A. J. Welch and M. J. C. van Gemert (Plenum Press, New York, 1995), pp. 73-100.

Complication of laser-based image reconstruction

• X-ray

• Laser

Modulation of light induces beam narrowing

= 0

0

wide beam

narrow beam

Transverse light beam waist

Pulse width shrinks with increasing frequency

Distance fromoptical axis

Intensity I

ISU filed patent application in 2005

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Beyond theory: experiment?

InputLaser

OutputFiber z

Laboratory measurements for on axis light intensityS. Campbell, A. O’Connell, S. Menon, Q. Su and R. Grobe, PRE, submitted

0

4

8

0 10 20 30 40z [cm]

Log

(N)

experiment

simulation

theory I

theory II

-0.6 -0.4 -0.2 0 0.2 0.4 0.6

2

4

6

8

y [cm]

z=0cm

z=10cm

z=5cm

LightNewton, Edison lights (1879) up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

Matter creation from light?

E = mc2

Light = electron + positron

Mourou, Yanovsky

Opt. Ph. News 15, 40 (2004)

1026Laser intensity >

“Conjuring matter from light”Science, Aug, 29, 1997

“Real photons create matter”Physics News, Sept. 18, 1997

“Light work”New Scientist, Sept. 27, 1997

“Boom! From light comes matter”Photonics Spectra, Nov. 1997

“Matter from light”CERN Courier, Nov. 1997

“E=mc2, really”Scientific American, Dec. 1997

“Let there be matter”Discover, Dec. 1997

“Gamma rays create matter by plowing into laser light”Phys. Today, Feb 1998

Popular science articles on matter creation from light

Wave or particle description of matter ?

Traditional wave viewDirac Equation (1928)deals with physics after creation (no creation)

Particle viewQuantum Field Theory (1940s)deals with # of creation(no wave nature)

Computational QFTPhys. Rev. Lett. (2004) wave nature during creation(new framework)

?????????????

Man

y bod

y quan

tum

field

theo

ry

What are these nice graphs?

From quantum field theory to quantum mechanics

it x,t= [ c ·p–·A+c2+V ] x,t

(x,y,t) = <0|| (+)(x,t) c(+)(y,t) || (t=0)>

vacuumstate

positivefrequency

part

chargeconjugation

initialstate

S.S. Schweber, “An introduction to relativistic quantum field theory”

Krekora, Su, Grobe, PRL 92, 040406 (2004) ; PRL 93, 043004 (2004)Braun, Su, Grobe, PRA 59, 604 (1999)

C.H. Keitel, Cont. Phys. 42, 353 (2001)A.D. Bandrauk, H. Shen J. Phys. A, 7147 (1994)

Solution of the field operator for e– and e+

ˆ b p(t) ˆ b p' p U(t) p' p' ˆ d n'

p U(t) n'n' ˆ d n

(t) ˆ b p' n U(t) p' p' ˆ d n'

n U(t) n'n'

Dirac equation for field

Solution whereˆ b p(t)Wp(x) p ˆ d n

(t)Wn(x)nx,t

U(t)=T exp{–i∫0t dt’ [c·p–·A(x,t’)+c2+V(x,t’)]}

ˆ

ˆ

ˆ

ˆ

ˆ

Of course!

Now everything makes sense!

The space-time resolved pair creation

e– e+

energy

Sample projects that employed the new CQFT method

(1) Space time resolved pair creation

(2) Klein paradox, 70 years old

Phys. Rev. Lett. 92, 040406 (2004)

Phys. Rev. A 72, 064103 (2005)

(3) Localization and Zitterbewegung

Phys. Rev. Lett. 93, 043004 (2004)

(4) Entanglement

J. Mod. Opt. 52, 489 (2005)

(5) Modified Schwinger formula

Las. Phys. 15, 282 (2005)

(6) Supercritical bound states

Phys. Rev. Lett. 95, 070403 (2005)

(7) Interpretational difficulty in QED

Phys. Rev. A, 73, 022114 (2006)

Experimental verification?Time dependent colliding ions (existing)

Static supercritical field

Experimental plans:

CUOS Ann Arbor, Michigan

DESY Hamburg, Germany

GSI Darmstadt, Germany

SLAC Stanford, California

“Zeptotechnology is just around the corner”

The Economist, page 77 Feb 28 2004

Laser fields lead to new unions of

ParticleGravitational

AtomicPlasma

Astro-physicsCosmology

Zetta-watt

Zepto-seconds

Enlightened ?

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LightNewton, Edison lights (1879) up Manhattan (1882)

Laser usagesCD writer, player, laser pointer, scanner, light knife, cosmetic treatment, laser show

What’s in a laseractive medium, stimulated emission, resonatorMaiman, Townes, MIT echo off moon

Probing matter with lasersIonization process, world mapMedical imaging, patentMatter creation, Klein

Research vs educationILP approach

Graduate or Undergraduate

US, best graduate school system in the world> 50% Nobel in Science after WWII good research-industry relation

What about our pre-graduate educationCuts in education fundingFlat science fundingMath/Science not “cool” in school

Do we need to change the perception?

Large number of studentsLarge number faculty mentors National awardsShow cased at conferences

Center or Research and Education on NanostructuresCenter for Research and Instruction in Space PhysicsIntense Laser Physics Theory UnitSurface Science LabPolarized Electron LabAtomic StructureStatistical MechanicsNonlinear DynamicsMathematical Physics

Undergraduate physics research at ISU

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Undergraduate research at ILP

Our approachStart earlySmall group collaborationProject design, execution, completionKnow physics, math, programmingUse intuition, catch misconceptionCommunicate result with others

Thanks to funding agencies Big thanks to colleagues past and present

Support from CAS, RSP, Honors Program Physics faculty colleagues

Postdoctoral fellowsAll 35 undergraduate students

Especially Prof. Grobe for collaborations

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Thanks to Alex,Christina, and Jean!

Thanks for attending

and

enjoy some refreshment !

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