
chair: Frank Grossmann

09:00  09:25

Karen Hatsagortsyan
(MPI für Kernphysik, Heidelberg)
Limits of Strong Field Rescattering in the Relativistic Regime
Recollision for a laser driven atomic system is investigated in the relativistic regime. We find the relativistic recollision energy cutoff is independent of the ponderomotive potential Up, in contrast to the wellknown 3.2Up scaling, and determined by the ionization potential of the atomic system. The ultimate energy cutoff is limited by the available intensities of short wavelength lasers and cannot exceed a few thousand Hartree, setting a boundary for recollision based attosecond physics.

09:25  09:50

Michael Klaiber
(MPI für Kernphysik, Heidelberg)
Laserinduced ionization of atoms in the lowfrequency regime
The interaction of atomic systems with laser fields in the regime, where the typical time of the laser field oscillation is large compared with the orbit time of the bound system, is investigated. When additionally the field is weak compared with the atomic field strength the ionization happens via multiphoton ionization, for intermediate field strength tunnel ionization dominates and for strong fields overthebarrier ionization is the physical process. All three processes have clear intuitive physical pictures.
In this talk we will try to shed some light on the ionization process happening at parameters that are in the transition region of the three described processes, by presenting calculations of ionization probabilities and electron trajectories via a strongfield approximation and a perturbation theory in the laser field strength.

09:50  10:15

Darko Dimitrovski
(Aalborg University)
Highorder harmonic generation from gapped graphene
The interaction of gapped graphene (a class of materials similar or based on graphene) with strong fields is studied in the twoband approximation. First, we study the transition from perturbative to fully nonperturbative regime of HHG. Next, the signatures of FloquetBloch states in the loworder harmonic spectra are studied. We find fieldstrengthdependent shifts of the position of resonant peaks in the loworder harmonic spectra. These shifts are analogous to the ponderomotive shifts in the strong field physics.

10:15  10:40

Christoph H. Keitel
(MPI für Kernphysik, Heidelberg)
Foundations of Extreme LaserMatter Interaction

10:40  11:10

Group photo & coffee break


chair: Marcus Beims

11:10  11:35

Frank Grossmann
(TU Dresden)
The Pauli principle in semiclassical electron dynamics
In molecular dynamics calculations, the Pauli principle is
frequently enforced by complex Pauli potentials that tend to
keep the phase space distance of two fermionic particles
large. We show by a semiclassical simulation of a scattering
process between two electrons that no such potential is needed
if the dynamics is started from a suitably symmetrized initial
state and is described by the HermanKluk propagator [1].
[1] F. Grossmann, M. Buchholz, E. Pollak, and M. Nest,
Phys. Rev. A 89, 032104 (2014)

11:35  12:00

Gerhard Stock
(Universität Freiburg)
Vibrational Conical Intersections as a Mechanism of Ultrafast Vibrational Relaxation
Presenting true crossings of adiabatic potential energy surfaces, conical intersections are a paradigm of ultrafast and efficient electronic relaxation dynamics. The same mechanism is shown to apply also for vibrational conical intersections, which may occur when two highfrequency modes (such as OH stretch vibrations) are coupled to lowfrequency modes (such as hydrogen bonding modes). By derivation of a model Hamiltonian and its parametrization for a concrete example, the hydrogenbonded complex HCO−2 · H2O, the conditions that such conical intersections occur are identified and the consequences for the vibrational dynamics and spectra are demonstrated.

12:00  12:25

Michael Walter
(Universität Freiburg)
From few to many and back to single particles
The struggle with correlated particles that started 20 years ago continues until today. Basic understanding gained and critical thinking learned in early years spreads out now to more and more undefined stuff.

12:25  12:50

Ulrich Jentschura
(Missouri University of Science and Technology)
Adjacency graphs and longrange interactions of atoms in quasidegenerate states

13:00  14:00

Lunch and discussion


chair: John Broad

14:00  14:30

Walter Strunz
(TU Dresden)
Memories in quantum dynamics
I discuss the appearance of memory terms in open quantum system dynamics
and its relation to notions of Markovian vs. nonMarkovian evolution.
A stochastic version of the traditional NakajimaZwanzig approach is
presented.

14:30  15:00

Marcus Beims
(Universidade Federal do Parana)
Alignment of Lyapunov vectors to anticipate large peaks in chaotic systems
We argue that the alignment of Lyapunov vectors provides a quantitative criterion to predict the imminence of largeamplitude events in chaotic timeseries of observables generated by sets of ordinary differential equations. Explicit predictions are reported for a Rössler oscillator and for a semiconductor laser with optoelectronic feedback.

15:00  15:30

Volker Engel
(Universität Würzburg)
Effective nonadiabatic transitions in molecules: who cares?
We investigate the coupled electronnuclear dynamics in model systems showing
avoided crossings [1] and conical intersections [2], respectively.
It is demonstrated that the nuclear density conserves its initial Gaussian shape
when passing the nuclear configurations where strong nonadiabatic couplings exist.
This is in sharp contrast to the picture which evolves from an analysis within the basis of adiabatic electronic states. There, dramatic changes are seen in the dynamics of the different nuclear components of the total wave function. It is thus documented that, in the case of a highly efficient population transfer between the respective adiabatic states, neither the nuclear nor the electronic density
are influenced by the existence of the crossing or conical intersection.
This is the case because the nuclearelectronic wave packet moves on a potential energy surface
which changes its topology smoothly as a function of all particle coordinates.
[1] J. Albert, D. Kaiser, V. Engel, J. Chem. Phys. 144, 171103 (2016)
[2] K. Hader, J. Albert, E.K.U. Gross, V. Engel, J. Chem. Phys. 146, 074304 (2017)

15:30  16:00

Christoph Meier
(Universite Paul Sabatier)
Strongly driven exciton dynamics in semiconductor quantum dots: Markov or NonMarkov?
Numerical simulations and analytical results on the creation of excitons and biexcitons by short, strong laser pulses are presented. In particular, the interplay between strong external driving and dissipative effects due to the substrate phonons is analyzed.
One of the main experimental findings is a drivingdependent relaxation mechanism, which manifests itself both in the regime of Rabi oscillations as well as for adiabatic passage using chirped pulses.
The experiments are well reproduced by numerical simulations based on a NonMarkovian master equation approach, and the exciton dynamics for different pulses is analyzed in terms of its “nonMarkovian” or “Markovian” character.
Finally, an analytical model is constructed, which captures all of the experimental findings, and which allows to identify different dynamical regimes in terms of the quantum dot characteristics and laser parameters. On the basis of this model, clear indications on robust exciton and biexciton generation can be given, which are confirmed by recent experiments.

16:00  16:30

Coffee break


chair: Jim Feagin

16:30  17:00

Jamal Berakdar
(MartinLutherUniversity HalleWittenberg)
Few buddies reloaded
It's been a while since we last heard from progress in the fewbody problem. I will try to report on some efforts to break or justify this silence.

17:00  17:30

Klaus Richter
(University of Regensburg)
Forward into the past: quantum time mirrors
Echo phenomena are playing an important role, both in classical and quantum physics: Prominent examples are reunions on the classical side and spin echoes on the quantum side. However, the latter represent rather specific quantum systems living in a lowdimensional Hilbert space and involving only discrete degrees of freedom. Is it possible to generalize this concept to systems with continuous degrees of freedom governed by Theoretical Quantum Dynamics?

17:30  18:00

JanMichael Rost
(MPIPKS Dresden)
Physics and Clustering
Clusters are a form of matter in between atoms and the condensed phase.
I will describe how the respond to short intense light pulses
of different frequencies by ejecting electrons. Despite the manybody character, the highest photo electron energy follows from a simple description with recollision features of strong field dynamics.
As a result clustering phenomena of Freiburg’s Quantum Dynamics can be put into perspective…

18:00  18:30

Uwe Thumm
(Kansas State University)
Timeresolved photoemission from surfaces and nanoparticles
Attosecond timeresolved spectroscopy is a thoughtprovoking method for investigating the electronic dynamics in atoms [1], and this technique is now being transferred to the scrutiny of electronic excitations, electron propagation, and collective electronic (plasmonic) effects in solid surfaces [1,2,3] and nanoparticles [1,4,5]. Compared with photoemission from isolated gaseous atoms, numerical simulations of such experiments on complex targets require, in addition, the adequate modeling of (i) the target’s electronic band structure [2], (ii) elastic and inelastic scattering of released photoelectrons inside the solid [25], (iii) surface and bulk collective electronic excitations [1,4,5], (iv) the screening and reflection of the assisting IRlaser field at the solid surface [3], (v) the influence of equilibrating residual charge distributions on emitted photoelectrons, and (vi) the effect of spatially inhomogeneous plasmonic fields on the photoemission process [2,4].
This talk will review the extent to which photoelectron propagation in matter and the plasmonic response of nanostructures can be (a) represented in classical [1,5] and quantum mechanical [14] simulations and (b) retrieved in IRstreaked XUV [1,2,4,5] and IRXUV twophoton interference (RABBITT) [3] photoemission spectra. As examples, I will discuss our recent numerical results for photoemission from (adsorbatecovered) metal surfaces [2,3] (in comparison with experimental data) and from plasmonic 10 to 200 nm diameter spherical nanoparticles that show how spatiotemporal information of the subinfraredcycle plasmonic and electronic dynamics is embedded in timeresolved spectra [4,5].
[1] U. T., Q. Liao, E. M. Bothschafter, F. Süßmann, M. F. Kling, R. Kienberger, in: Handbook of Photonics, Vol. 1, (Wiley 2015).
[2] Q. Liao, U. T., Phys. Rev. A 89, 033849 (2014); ibid. 92, 031401(R) (2015).
[3] M. J. Ambrosio, U. T., Phys. Rev. A 94, 063424 (2016).
[4] J. Li, E. Saydanzad, U. T., Phys. Rev. A 94, 051401(R) (2016).
[5] E. Saydanzad, J. Li, U. T., Phys. Rev. A, just submitted.
Supported in part by the US NSF and DoE.

19:30  21:00

Workshop Dinner (Watzke Brauereiausschank am Goldenen Reiter, http://www.watzke.de/watzke_am_goldenen_reiter.html)


Long Night of Science (http://www.wissenschaftsnachtdresden.de/)
