Name: Studying Quantum Mechanics in the Time Domain
Start: 2011-08-22T08:00:00+02:00
End: 2011-09-16T18:00:00+02:00
Location: No location set

Monday, 22 August 2011

10:00

10:00 - 20:30
Room: FR4, Oskar Klein Auditorium

Registration
Registration
10:00 - 12:00
Room: AlbaNova Main Entrance

12:00 Lunch
Lunch
12:00 - 13:00

13:00 Registration
Registration
13:00 - 13:45
Room: AlbaNova Main Entrance

13:45 Welcome!
Welcome!
13:45 - 14:00
Room: FR4, Oskar Klein Auditorium
14:00 Spectroscopy with attosecond time resolution - Ferenc Krausz (MPI Garching)
Spectroscopy with attosecond time resolution
- Ferenc Krausz (MPI Garching)
14:00 - 15:00
Room: FR4, Oskar Klein Auditorium Electronic motion is a key process in a wide range of modern technologies, including micro- to nano-electronics, photovoltaics, bioinformatics, molecular biology, and medical as well as information technologies. The atomic-scale motion of electrons typically unfolds within tens to thousands of attoseconds (1 attosecond [as] = 10-18 s). Recent advances in laser science have opened the door to watching and controlling these hitherto inaccessible microscopic dynamics [1]-[14]. Key tools include waveform-controlled few-cycle laser light and attosecond extreme ultraviolet pulses. They permit control of atomic-scale electric currents just as microwave fields control currents in nanometer-scale semiconductor chips. By analogy to microwave electronics, we have dubbed this new technology "lightwave electronics" [10,12]. Lightwave electronics provides - for the first time - real-time access to the motion of electrons on atomic and sub-atomic scales. Insight into and control over microscopic electron motion are likely to be important for developing brilliant sources of X-rays, understanding molecular processes relevant to the curing effects of drugs, the transport of bioinformation, or the damage and repair mechanisms of DNA, at the most fundamental level, where the borders between physics, chemistry and biology disappear. Once implemented in condensed matter, the new technology will be instrumental in advancing electronics and electron-based information technologies to their ultimate speed: from microwave towards lightwave frequencies. [1] M. Hentschel et al., Nature 414, 509 (2001) [2] R. Kienberger et al., Science 291, 1923 (2002) [3] A. Baltuska et al., Nature 421, 611 (2003) [4] R. Kienberger et al., Nature 427, 817 (2004) [5] E. Goulielmakis et al., Science 305, 1267 (2004) [6] M. Drescher et al., Nature 419, 803 (2002) [7] M. Uiberacker et al., Nature 446, 627 (2007) [8] M. Kling et al., Science 312, 246 (2006) [9] A. Cavalieri et al., Nature 449, 1029 (2007) [10] E. Goulielmakis et al., Science 317, 769 (2007) [11] E. Goulielmakis et al., Science 320, 1614 (2008) [12] F. Krausz, M. Ivanov, Rev. Mod. Phys. 81, 163 (2009). [13] M. Schultze et al., Science 328, 1658 (2010). E. Goulielmakis et al., Nature 466, 739 (2010).
15:00 Coffee
Coffee
15:00 - 15:30
15:30 Attosecond Physics using Attosecond pulse trains - Anne L'Huillier (Lund University)
Attosecond Physics using Attosecond pulse trains
- Anne L'Huillier (Lund University)
15:30 - 16:30
Room: FR4, Oskar Klein Auditorium
16:30 Ultra-fast dynamics: Pump-Probe Experiments at FELs - Joachim Ullrich (MPI Heidelberg)
Ultra-fast dynamics: Pump-Probe Experiments at FELs
- Joachim Ullrich (MPI Heidelberg)
16:30 - 17:30
Room: FR4, Oskar Klein Auditorium
17:30 Welcome Reception at Nordita
Welcome Reception at Nordita
17:30 - 20:30
Tuesday, 23 August 2011
10:00 Attoclock reveals tunnel delay time and tunnel geometry in strong field ionization - Ursula Keller (ETH Zürich)
Attoclock reveals tunnel delay time and tunnel geometry in strong field ionization
- Ursula Keller (ETH Zürich)
10:00 - 11:00
Room: FR4, Oskar Klein Auditorium Theoretical models often fail to describe the dynamics due to numerical limitations, and we need to develop better approximate models for the ultrafast dynamics on an atomic scale. Novel time-resolved attosecond streaking techniques such as energy streaking and the attoclock, and in addition more recently interference techniques are currently being applied in an attempt to answer a very fundamental question in quantum mechanics: how fast can light remove a bound electron from an atom or a solid? We have used the attoclock technique [1] to gain more insight in strong laser field ionization, where a the strong laser field bends the binding potential to emit an electron by tunneling (tunnel ionization). Initially we have measured an instantaneous tunneling delay time in helium [1]. More recently we have confirmed no measurable tunneling delay time over a larger intensity regime with the Keldysh parameter well below unity for the first time (which is actually the real regime of tunneling) and extend our studies to argon with the same outcome with regards to the tunneling delay time [2]. Tunneling is described by three important parameters: tunneling rate, tunneling time and tunnel geometry. While the first two have been discussed widely in the last decades, we have recently determined the tunnel geometry for the first time [2]. The attoclock is a unique tool that directly reveals the tunnel geometry and therefore the more complex electron ion interaction. We show that the Coulomb correction alone is not sufficient and multi-electron effects can be important even for atoms such as argon. Possible systematic errors are eliminated with the attoclock by simply using clockwise and anticlockwise streaking fields. In collaboration with Prof. Lars B. Madsen’s group from Aarhus University we developed a modified semiclassical model that agrees well with our attoclock experiments [2]. The theory represents a "textbook" quality and represents everything a theory has to do: describes the experiment, relies on accurate assumptions, and new effects are clearly identified, stated and quantified. Even more so, the polarizabilities that enters the model are calculated and measured using other independent methods. Attosecond measurements have typically used attosecond streaking techniques for which the detailed electron ion interaction need to be understood on an attosecond time scale. If this interaction is not understood correctly, wrong conclusions could be drawn on possible time delays. To date attosecond streaking has been applied to atomic, molecular or solid target. Multielectron effects as pointed out here are even more important for more complex targets. [1] P. Eckle, A. Pfeiffer, C. Cirelli, A. Staudte, R. Dörner, H. G. Muller, M. Büttiker, U. Keller, Attosecond ionization and tunneling delay time measurements Science, vol. 322, pp. 1525-1529, 2008 [2] A. N. Pfeiffer, C. Cirelli, M. Smolarski, D. Dimitrovski, M. Abu-samha, L. B. Madsen, U. Keller, Attoclock reveals geometry of laser-induced tunnel ionization arXiv:1103.4803v1 [physics.atom-ph] online 25. March 2011 
10:00 - 19:00
Room: FR4, Oskar Klein Auditorium

11:00 Coffee
Coffee
11:00 - 11:30
11:30 The Reincarnation of Multiphoton Processes - Peter Lambropoulos (University of Crete)
The Reincarnation of Multiphoton Processes
- Peter Lambropoulos (University of Crete)
11:30 - 12:30
Room: FR4, Oskar Klein Auditorium About fifty years ago, the first laser-induced two-photon absorption in an atomic vapor was observed in Cesium. With the subsequent developments in laser technology, the field of multiphoton (MP) processes evolved through a series of stages, involving harmonic generation, resonantly enhanced multiphoton ionization (REMPI), effects of field correlations in non-linear processes, to mention a few. With the advent of sub-picosecond, Fourier limited and eventually few-cycle sources, over the last 20 years, the paradigm shifted to what is now known as strong field phenomena and attosecond physics, in terms of the single-active electron approximation, dominated by recollision dynamics. Thus multiphoton processes per se went into a dormant stage, leaving behind certain tools such as REMPI. The appearance of strong, sub-picosecond, radiation in a broad frequency range, from the XUV to hard X-rays, has now revived MP concepts and techniques, but in an entirely new context. Whereas traditional MP processes under infrared to UV radiation involved exclusively valence electrons, in the new paradigm it is inner electrons that dominate the chain of events triggered by the exposure to strong, short wavelength radiation. After a brief historical review of the main stages and concepts of MP processes under long wavelength radiation, I discuss their connection to the short wavelength context, using specific examples of observations in the XUV to soft X-ray range, in order to illustrate the similarities and differences between the two paradigms. In particular the operational meaning of concepts such as strong field, short pulse, sequential versus direct multiple ionization, double resonance, etc. are discussed and illustrated through the application to specific systems.
12:30 Lunch
Lunch
12:30 - 14:30
14:30 Attosecond molecular spectroscopies with XUV harmonic radiation - Alfred Maquet (UPMC Paris)
Attosecond molecular spectroscopies with XUV harmonic radiation
- Alfred Maquet (UPMC Paris)
14:30 - 15:30
Room: FR4, Oskar Klein Auditorium
15:30 Coffee
Coffee
15:30 - 16:00
16:00 Hole dynamics and coherence - Robin Santra (DESY Hamburg)
Hole dynamics and coherence
- Robin Santra (DESY Hamburg)
16:00 - 17:00
Room: FR4, Oskar Klein Auditorium Photoionization of an atom or a molecule leads, in general, to the formation of a superposition of ionic eigenstates. That superposition cannot, in general, be described in terms of a wave function, but a description in terms of a reduced density matrix (a statistical mixture) is required. In the first part of the talk, ultrafast, partially coherent hole dynamics driven by spin-orbit coupling will be analyzed in terms of a time-dependent multichannel mean-field theory [1]. This theory will be compared with the results of an attosecond transient absorption experiment on strong-field-ionized krypton atoms [2]. In the second part of the talk, a new implementation of time-dependent configuration interaction singles (TDCIS) will be discussed [3]. Using TDCIS calculations, it will be shown that photoelectron-mediated interchannel coupling causes ion decoherence in attosecond photoionization. As a consequence, even if the spectral bandwidth of the ionizing pulse exceeds the energy splittings among the hole states involved, perfectly coherent hole wave packets cannot be formed [4] [1] N. Rohringer and R. Santra, Phys. Rev. A 79, 053402 (2009). [2] E. Goulielmakis, Z.-H. Loh, A. Wirth, R. Santra, N. Rohringer, V. S. Yakovlev, S. Zherebtsov, T. Pfeifer, A. M. Azzeer, M. F. Kling, S. R. Leone, and F. Krausz, Nature 466, 739 (2010). [3] L. Greenman, P. J. Ho, S. Pabst, E. Kamarchik, D. A. Mazziotti, and R. Santra, Phys. Rev. A 82, 023406 (2010). [4] S. Pabst, L. Greenman, P. J. Ho, D. A. Mazziotti, and R. Santra, Phys. Rev. Lett. 106, 053003 (2011). 
17:00 Get together (drinks and snacks) at Nordita
Get together (drinks and snacks) at Nordita
17:00 - 19:00
Wednesday, 24 August 2011

10:00

10:00 - 22:00
Room: FB53
Pulse Shaping for Coherent Control, 2D Spectroscopy, and Ultrafast Nano-Optics - Tobias Brixner (University of Würtzburg)
Pulse Shaping for Coherent Control, 2D Spectroscopy, and Ultrafast Nano-Optics
- Tobias Brixner (University of Würtzburg)
10:00 - 11:00
Room: FB53 Shaped femtosecond laser pulses have found applications in many different research areas of the ultrafast sciences. Flexible manipulation of electric-field evolution provides novel opportunities for studying light-matter interaction in various quantum-mechanical systems. This talk provides illustrative examples from coherent control, coherent two-dimensional spectroscopy, and ultrafast nano-optics, with environments ranging from the gas phase over molecules in liquids to solid-state surfaces. Although traditionally there has not been a lot of interaction between the three mentioned research fields, the common theme of shaped pulses can serve as a connecting element, opening new avenues of scientific investigation.
11:00 Coffee
Coffee
11:00 - 11:30
11:30 Analysis and control of electronic motion in the time domain - E. K. U. Gross (MPI Halle)
Analysis and control of electronic motion in the time domain
- E. K. U. Gross (MPI Halle)
11:30 - 12:30
Room: FB53 This lecture is about how electronic motion can be monitored, analyzed and, ultimately, controlled, in real time. In particular: (i) A novel approach to describe electronic transport through single molecules or atomic wires, sandwiched between semi-infinite leads, will be presented. The basic idea is to propagate the time-dependent Kohn Sham equations in time upon ramping up a bias between the metallic leads. In this way, genuinely time-dependent phenomena, not accessible in the standard Landauer approach, can be addressed. For example, employing an Anderson model, we demonstrate that Coulomb blockade corresponds, in the time-domain, to a periodic charging and discharging of the quantum dot [1]. (ii) With modern pulse-shaping facilities, the control of electronic motion is becoming more and more realistic. By combining quantum optimal control theory with TDDFT, we calculate shaped laser pulses suitable to control, e.g., the chirality of currents in quantum rings [2], the location of electrons in double quantum dots, as well as the enhancement of a single peak in the harmonic spectrum of atoms and molecules. (iii) In all practical TDDFT calculations, approximate forms of the exchange-correlation potential need to be employed. One of the most popular approximations, the adiabatic local-density approximation (ALDA) will be analyzed as to whether the main error comes from the adiabaticity assumption, i.e. locality in time, or from the LDA, i.e. locality in space. For an exactly solvable model where the exact adiabatic approximation can be extracted, we find the surprising fact, that the adiabaticity assumption can be an excellent approximation even in highly intense laser fields [3]. (iv) Finally, the coupling between electronic and nuclear motion will be addressed. As a first step towards a full ab-initio treatment of the coupled electron-nuclear motion in time-dependent external fields, we deduce an exact factorization of the complete wavefunction into a purely nuclear part and a many-electron wavefunction which parametrically depends on the nuclear configuration. We derive formally exact equations of motion for the nuclear and electronic wavefunctions [4]. These exact equations lead to a rigorous definition of time-dependent potential energy surfaces as well as time-dependent geometric phases. With the simple example of the hydrogen molecular ion in a laser field we demonstrate the significance of these concepts in understanding the full electron-ion dynamics. In particular, the time-dependent potential energy surfaces are shown to represent a powerful tool to analyse and interpret different (direct vs. tunneling) types of dissociation processes. [1] S. Kurth, G. Stefanucci, E. Khosravi, C. Verdozzi, E.K.U. Gross, Phys. Rev.Lett.104, 236801 (2010). [2] E. Räsänen, A. Castro, J. Werschnik, A. Rubio, E.K.U. Gross, Phys. Rev. Lett. 98,157404 (2007). [3] M. Thiele, E.K.U. Gross and S. Kümmel, Phys. Rev. Lett. 100, 153004 (2008). [4] A. Abedi, N.T. Maitra, E.K.U. Gross, Phys. Rev. Lett. 105, 123002 (2010).
12:30 Lunch
Lunch
12:30 - 14:30
14:30 Read-out and coherent control of electron spin qubits in quantum dots - Lieven Vandersypen (TU Delft)
Read-out and coherent control of electron spin qubits in quantum dots
- Lieven Vandersypen (TU Delft)
14:30 - 15:30
Room: FB53 Quantum information processing requires accurate control of the time evolution of physical systems at the level of single quantum mechanical degrees of freedom. I will present our work on the coherent manipulation of individual and coupled electron spins in semiconductor quantum dots, and on independent read-out of the spins.
15:30 Coffee
Coffee
15:30 - 16:00
16:00 Exploring few- and many-body physics with frozen Rydberg gases - Matthias Weidemüller (University of Heidelberg)
Exploring few- and many-body physics with frozen Rydberg gases
- Matthias Weidemüller (University of Heidelberg)
16:00 - 17:00
Room: FB53 The investigation of Rydberg atoms has a long history, dating back to the early days of Atomic Physics. Rydberg gases at ultra-low temperatures were first realized only in the last decade by combining advances in atom manipulation and cooling with narrow-band laser excitation of Rydberg states. The exquisite controlof the electronic excitation and the centre-of-mass motion, employing external fields, allows one to exploit the unique and exaggerated properties of Rydberg atoms, namely their large size, large electronic orbiting times, small electronic binding energy, and extremely strong dipole–dipole and van derWaals interactions. The combination of strong atomic interactions and a high level of quantum control, reaching down to the single atom level, gives rise to both new fundamental physics and interesting applications of Rydberg gases, including for example investigations of novel phases of quantum matter, and controlled preparation of atom or photon entanglement. In my presentation I will give a general introduction into the field and discuss some recent experiments of my group.
18:00 Dinner at AlbaNova
Dinner at AlbaNova
18:00 - 22:00
Thursday, 25 August 2011

10:00

10:00 - 11:00
Room: Nordita building

14:30 coffee
coffee
14:30 - 15:00

15:00

15:00 - 16:00
Friday, 26 August 2011

09:30 coffee
coffee
09:30 - 10:00

10:00 Talk by Luca Argenti: Vibrationally resolved photoelectron spectroscopy of CH4: Studying electron diffraction from within
Talk by Luca Argenti: Vibrationally resolved photoelectron spectroscopy of CH4: Studying electron diffraction from within
10:00 - 11:00
Room: Nordita building

14:30 coffee
coffee
14:30 - 15:00
Saturday, 27 August 2011

09:15 Trip to the Archipelago (Sandhamn) with boat (whole day)
Trip to the Archipelago (Sandhamn) with boat (whole day)
09:15 - 18:00
Sunday, 28 August 2011