Download presentation

1
**Attosecond Flashes of Light**

– Illuminating electronic quantum dynamics – XXIIIrd Heidelberg Graduate Days Lecture Series Thomas Pfeifer InterAtto Research Group MPI – Kernphysik, Heidelberg

2
Fourier Transform

3
**Contents Basics of short pulses and general concepts**

Attosecond pulse generation Mechanics of Electrons single electrons in strong laser fields Attosecond Experiments with isolated Atoms Multi-Particle Systems Molecules multi-electron dynamics (correlation) Attosecond experiments with molecules / multiple electrons Ultrafast Quantum Control of electrons, atoms, molecules Novel Directions/Applications Technology

4
**Mathematics of Ultrashort pulses**

spectral phase Taylor expansion dispersion

5
**absolute (carrier-envelope) phase**

6
**Windowed Fourier Transform**

‘Gabor Transform’ frequency [arb. u.] frequency [arb. u.]

7
**Contents Basics of short pulses and general concepts**

Attosecond pulse generation Mechanics of Electrons single electrons in strong laser fields Attosecond Experiments with isolated Atoms Multi-Particle Systems Molecules multi-electron dynamics (correlation) Attosecond experiments with molecules / multiple electrons Ultrafast Quantum Control of electrons, atoms, molecules Novel Directions/Applications Technology

8
**Ultrashort Pulses 1 fs = 10-15 s 1000000000000000 work power = time**

Observation of fast processes concentration of energy in time and space Ref: Ulrich Weichmann, Department of Physics, Wuerzburg University

9
**Short Pulses Intense Laser Fields**

Power = Energy Time 100 J 5 fs = = 20 GW e.g. THz, IR, vis., UV, X-ray e- e- Light conversion X+ X+ X+ X+ X+ e- e- e- Plasma e.g. attosecond pulses femtosecond laser pulse 20 GW (100 m)2 = 2 1016 W cm2 relativistic effects above 1018W/cm2

10
**Supercontinuum generation**

11
**Attosecond pulse generation**

also known as: High-Order Harmonic Generation mechanism based on: sub-optical-cycle electron acceleration (laboratory-scale table-top) attosecond x-ray pulse atomic medium detector/ experiment femtosecond laser pulse laser intensity: >1014 W/cm2

12
**High-(order) harmonic generation**

first signs intensity: W/cm2 wavelength: nm pulse duration: 1 ps McPherson et al. J. Opt. Soc. Am. B 21, 595 (1987)

13
**High-(order) harmonic generation**

first signs M. Ferray, A. L’Huillier et al. J. Phys. B 21, L31 (1988) intensity: ~1013 W/cm2 wavelength: nm pulse duration: 1 ps

14
**High-harmonic generation (HHG)**

80 fs 800 nm 5·1014 W/cm2 1 kHz Zr + Parylene-N filter in Neon (Ne) in Xenon (Xe) H3 80 fs 800 nm 3·1014 W/cm2 1 kHz H11 H9 H7 H5 H13 H15

15
**Contents Today Attosecond Pulses**

Classical and quantum mechanics of electrons and experiments with isolated atoms - Classical Motion of Electrons definition of important quantities - Quantum Mechanics · Electron dynamics in (intense) laser fields · Ionization - High-harmonic generation: quantum mechanical view - Experiments with attosecond Pulses - Quantum state interferometry

16
**Forces on Electrons in Atoms**

E(t) Intensity I ~ W/cm2 Force F = nN Mass me= 9.1∙10-31 kg acc a = 1.5∙1022 m/s2 e- F 2000 as velocity v = 3 ∙106 m/s = 1% c (speed of light) “assumed constant acceleration from rest for 200 attoseconds” Grundzustandswellenfunktionen aus \\HHG\Fortran\03_03_10 E(t) optical light wave 1 attosecond (1 as = s) compares to 1 second as 1 second compares to more than the age of the universe (~15 Billion years)

17
**Electron in Laser Field**

E(t)=E0cos(wt) linearly polarized along x axis a(t)= -eE0cos(wt) acceleration v(t)= sin(wt) eE0 w velocity (dt a) x(t)= cos(wt) eE0 w2 position (dt v) Up=Ekin,av= e2E02 4mw2 eV ponderomotive potential = Il29.33 mm21014 W/cm2 ap= x0 = eE0 w2 ponderomotive radius

18
**High-(order) harmonic generation**

first signs M. Ferray, A. L’Huillier et al. J. Phys. B 21, L31 (1988) intensity: ~1013 W/cm2 wavelength: nm pulse duration: 1 ps

19
Three-step model P. Corkum, Phys. Rev. Lett. 71, 1994 (1993) Kulander et al. Proc. SILAP, 95 (1993)

20
**High-harmonic generation (HHG)**

21
**High-(order) harmonic generation**

first signs M. Ferray, A. L’Huillier et al. J. Phys. B 21, L31 (1988) intensity: ~1013 W/cm2 wavelength: nm pulse duration: 1 ps

22
**High-harmonic generation**

Hentschel et al. (Krausz group) Nature 414, 509 (2001) P. Corkum, Phys. Rev. Lett. 71, 1994 (1993)

23
**Isolated Attosecond-pulse production**

(the conventional method) Hentschel et al. (Krausz group) Nature 414, 509 (2001) high- pass filter “cos pulse” “sin pulse”

24
**Attosecond pulse generation**

Hentschel et al. Nature 414, 509 (2001)

25
**Absolute Phase (CEP) effects**

CEP j CEP j+p/2 Baltuška et al. Nature 421, 611 (2003) ~ 6 femtosecond CEP (Absolute phase) stabilized laser pulse

26
**Attosecond Beamline at Berkeley**

27
**Attosecond Beamline at Berkeley**

Time-of-Flight Detection of electrons Velocity-Map imaging of electrons or ions Piezo- controlled split mirror MCP piezo High-harmonic generation Filter on pellicle Split mirror 6-fs IR pulse CEP stabilized Iris Metal filter XUV grating X-ray CCD CCD

28
**Mo/Si multilayer mirror**

29
**Attosecond Beamline at Berkeley**

Time-of-Flight Detection of electrons Velocity-Map imaging of electrons or ions Piezo- controlled split mirror MCP piezo High-harmonic generation Filter on pellicle Split mirror 6-fs IR pulse CEP stabilized Iris Metal filter XUV grating X-ray CCD CCD

30
**Short pulse measurement**

“to measure a fast event, you need an at least equally fast probe” - Autocorrelation ‘Auto...’ -> self... - Frequency-Resolved Optical Gating FROG, building upon Autocorrelation - Temporal Analysis by Dispersing a Pair Of Light Electric Fields TADPOLE - Spectral Interferometry for Direct Electric Field Reconstruction SPIDER, building upon TADPOLE

31
Autocorrelation linear (no crystal) nonlinear (with crystal)

32
**Attosecond autocorrelation measurements**

Tzallas et al.(Witte, Tsakiris) Nature 426, 267 (2003)

33
**Attosecond autocorrelation measurements isolated pulses**

Sekikawa et al.(Watanabe) Nature 432, 605 (2004)

34
**Attosecond autocorrelation measurements pulse trains**

Tzallas et al.(Witte, Tsakiris) Nature 426, 267 (2003)

35
**FROG idea analysis by iterative algorithm measure spectrum as**

D. J. Kane and R. Trebino, Opt. Lett. 18, 823 (1993) measure spectrum as a function of time delay 2-dim. data sets: ‘FROG-trace’ analysis by iterative algorithm Ref:

36
**Goulielmakis et al. (Krausz group), Science 305, 1267 (2004)**

Streaking Goulielmakis et al. (Krausz group), Science 305, 1267 (2004)

37
FROG-CRAB Y. Mairesse and F. Quéré, Science 71, (2005)

38
**high-harmonic generation**

intense laser field acting on single atom probability distribution p(x,y)=|Y(x,y)|2 for the electronic wavefunction laser polarization Film zusammengestellt aus \\HHG\Fortran\03_03_11 Wellenfunktion gegen py aus \\HHG\Fortran\03_03_11\Evaluate corrected

39
**Time-dependent quantum mechanics**

40
**Time-dependent quantum mechanics position and momentum space representation**

~

41
Wave packets

42
Coherence Also for Quantum wavepackets Dj=?

43
Quantum “Motion”

44
Wave packets

45
**Ionization Photoelectric effect (direct transition)**

Strong electric field (Tunneling) |1> U: barrier height |0> w: barrier width 1st order perturbation theory tunneling rate

46
**Electron in Laser Field**

E(t)=E0cos(wt) linearly polarized along x axis a(t)= -eE0cos(wt) acceleration v(t)= sin(wt) eE0 w velocity (dt a) x(t)= cos(wt) eE0 w2 position (dt v) Up=Ekin,av= e2E02 4mw2 eV ponderomotive potential = Il29.33 mm21014 W/cm2 ap= x0 = eE0 w2 ponderomotive radius

47
**Electron in Laser Field**

E(t)=E0cos(wt) linearly polarized along x axis a(t)= -eE0cos(wt) acceleration v(t)= sin(wt) eE0 w velocity (dt a) A(t)= -e dt’ E(t’) = v(t) - t Vector potential (Coulomb gauge) momentum/velocity gauge Schrödinger equation: (dipole approximation) length gauge

48
**Electron in Laser Field**

E(t)=E0cos(wt) linearly polarized along x axis a(t)= -eE0cos(wt) acceleration v(t)= sin(wt) eE0 w velocity (dt a) A(t)= -e dt’ E(t’) = v(t) - t Vector potential (Coulomb gauge, A=0) Schrödinger equation: (dipole approximation) momentum/velocity gauge [H,p]=0 p conserved, solution:

49
**Keldysh formalism Photoelectric effect (direct transition)**

1st order perturbation theory |1> |0> Strong electric field (Tunneling) tunneling rate w: barrier width U: barrier height

50
ADK formula Ammosov, Delone, and Krainov, Sov. Phys. JETP 64, 1191 (1986) Ionization rate (in a.u.): Strong electric field (Tunneling) tunneling rate w: barrier width U: barrier height Experimental checks: Augst et al., J. Opt. Soc. Am. B 8, 858 (1991)

51
**Keldysh formalism Strong electric field (Tunneling) U: barrier height**

tunneling rate Strong electric field (Tunneling) w: barrier width U: barrier height

52
**Strong-Field Approximation**

Strong electric field V(t)=rE(t) V r e-

53
**High Harmonics Quantum Mechanical**

54
**high-harmonic generation**

intense laser field acting on single atom probability distribution p(x,y)=|Y(x,y)|2 for the electronic wavefunction laser polarization Film zusammengestellt aus \\HHG\Fortran\03_03_11 Wellenfunktion gegen py aus \\HHG\Fortran\03_03_11\Evaluate corrected

55
Wavepacket spreading

Similar presentations

OK

Classical and quantum electrodynamics e®ects in intense laser pulses Antonino Di Piazza Workshop on Petawatt Lasers at Hard X-Ray Sources Dresden, September.

Classical and quantum electrodynamics e®ects in intense laser pulses Antonino Di Piazza Workshop on Petawatt Lasers at Hard X-Ray Sources Dresden, September.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on mathematics for class 9 Ppt on collection of data for class 11 Download ppt on android Ppt on different wild animals Ppt on l&t finance career Ppt on weapons of mass destruction robin Ppt on business plan with example Ppt on 3g mobile technology Ppt on recycling of wastewater effluent Moving message display ppt on ipad