Speakers

Synopsis: X-ray free-electron lasers have opened new frontiers in X-ray science. Unprecedented intensities at Angstrom wavelengths have led to the discovery of X-ray phenomena such as nonlinear multiphoton absorption in atoms, molecules and clusters; atomic X-ray lasing; induced transparency; and stimulated emission. This talk will review our current understanding of these phenomena that may eventually lead to dynamic 3D imaging of complex systems at atomic resolution.

Biography: Linda Young is the Director of the X-ray Science Division at the Argonne National Laboratory (ANL). She received her S.B. from the Massachusetts Institute of Technology and Ph.D. from the University of California, Berkeley. After a postdoc position at the University of Chicago, she joined the Physics Division of ANL, where she has served as a Group Leader of AMO Physics before she was appointed to her present post. She currently also holds a joint appointment in the James Franck Institute and Department of Physics at the University of Chicago. She has served as the Chair of DAMOP of the American Physical Society and is currently on the Scientific Advisory Committees of various X-ray light sources. She is a fellow of the American Physical Society and was recently awarded a Helmholtz International Fellowship.

Hide synopsis and biography

Synopsis: Three decades of positron trap and beam development have enabled new investigations such as the creation and study of anti-hydrogen atoms, the positronium molecule (Ps₂), and Feshbach-resonances in annihilation that lead to positron-molecule bound states. This talk will discuss highlights of these and other successes and the critical tools that enabled them. It will conclude with a brief discussion of prospects for further progress on topics of keen interest including study of lepton many-body physics: Ps-atom BECs and classical (e⁺- e^-) "pair plasmas."

Biography: Cliff Surko is a Distinguished Professor of Physics at the University of California, San Diego. Following a Ph.D. at UC Berkeley, he did condensed matter, plasma and fluid research at AT&T Bell Laboratories before coming to UCSD in 1988. He is a fellow of the American Physical Society (APS) and the American Association for the Advancement of Science, and he is the recipient of the 2014 APS James Clerk Maxwell Prize in Plasma Physics. He and his collaborators have invented and developed numerous trap- and beam-based tools for positron research. His current work exploits plasma techniques to study atomic and plasma physics with positrons, including positron-molecule bound states and the Feshbach resonance phenomena that enable their formation.

Hide synopsis and biography

Synopsis: In this talk I will discuss charge and energy transfer processes in meV-keV collisions of heavy projectiles and different types of targets ranging from single isolated molecules to small molecules, bio-molecules, and complex molecular clusters with thousands of atoms. I will discuss the mechanisms behind these processes and behind related collision-induced molecular fragmentation and growth processes. I will highlight key experimental and theoretical results, which have been particularly useful in gaining an understanding of these phenomena, and will also make a comparison with related results for photon and lepton interactions. I will briefly mention new instrumental developments for detailed studies of photon and particle interactions with heavy particles in the form of atomic, molecular, and cluster ions.

Biography: Henrik Cederquist is a Full Professor at Stockholm University. He received his PhD in atomic physics from the Royal Institute of Technology (KTH) in Stockholm in 1986 under supervision of Leif Liljeby, Sven Mannervik, and Anders Bárány. In 1986-1987 he was a post-doc at the University of Tennessee and Oak Ridge National Laboratories with Ivan Sellin. In 1989 he did his Habilitation at KTH, and in 1997 he received a Wallmarkska prize from the Royal Academy of Sciences for his work on collisions with fullerenes. In 1999 he was appointed to his present post. Henrik Cederquist was an International Chair of the ECAMP conference in Salamanca, Spain in 2010 and an Elected Member of the Science Council of the Swedish Research Council in 2013-2018.

Hide synopsis and biography

Synopsis: Dipolar interactions in gases are fundamentally different from the usual van der Waals forces. Besides the anisotropy, the dipolar interaction is nonlocal and as such allows for self organized structure formation. Candidates for dipolar species are polar molecules, Rydberg atoms and magnetic atoms. In this talk we focus on the latter.

More than ten years ago the first dipolar effects in a quantum gas were observed in an ultracold Chromium gas. By the use of a Feshbach resonance a purely dipolar quantum gas was observed three years after [1]. Dipolar interaction effects have been observed in lattices and polar molecules. Recently it became possible to study degenerate gases of lanthanides, among which one finds the most magnetic atoms. The recent observation of their collisional properties includes the emergence of quantum chaos and very broad resonances [2,3]. Similar to the Rosensweig instability in classical magnetic ferrofluids, self organized structure formation was expected. In our experiments with quantum gases of dysprosium atoms we could recently observe the formation of a droplet crystal [4]. In contrast to theoretical mean field based predictions the superfluid droplets did not collapse. We find that this unexpected stability is due to beyond mean field quantum corrections of the Lee-Huang-Yang type [5,6]. Similar to liquid helium droplets we observe and study self-bound droplets [7] which can interfere with each other. These and other effects will be discussed in the lecture.

[1] T. Lahaye, C. Menotti, L. Santos, M. Lewenstein, and T. Pfau, "The physics of dipolar bosonic quantum gases", Rep. Prog. Phys. 72, 126401 (2009)
[2] T. Maier, I. Ferrier-Barbut, H. Kadau, M. Schmitt, M. Wenzel, C. Wink, T. Pfau, K. Jachymski, P. S. Julienne, "Broad Feshbach resonances in collisions of ultracold Dysprosium atoms", Phys. Rev. A 92, 060702(R) (2015)
[3] T. Maier, H. Kadau, M. Schmitt, M. Wenzel, I. Ferrier-Barbut, T. Pfau, A. Frisch, S. Baier, K. Aikawa, L. Chomaz, M. J. Mark, F. Ferlaino, C. Makrides, E. Tiesinga, A. Petrov, S. Kotochigova, "Emergence of chaotic scattering in ultracold Er and Dy", Phys. Rev. X 5, 041029 (2015)
[4] H. Kadau, M. Schmitt, M. Wenzel, C. Wink, T. Maier, I. Ferrier-Barbut, T. Pfau "Observing the Rosensweig instability of a quantum ferrofluid", Nature 530, 194 (2016)
[5] T. D. Lee, K. Huang, and C. N. Yang, " Eigenvalues and Eigenfunctions of a Bose System of Hard Spheres and Its Low-Temperature Properties", Phys. Rev. 106, 1135 (1957)
[6] I. Ferrier-Barbut, H. Kadau, M. Schmitt, M. Wenzel, T. Pfau, "Observation of quantum droplets in a strongly dipolar Bose gas", Phys. Rev. Lett. 116, 215301 (2016)
[7] M . Schmitt, M. Wenzel, F. Böttcher, I. Ferrier-Barbut, and T. Pfau, "Self-bound droplets of a dilute magnetic quantum liquid", arXiv:1607.07355 (2016), Nature (accepted)

Biography: Tilman Pfau is a chair for Photonics at the Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart. He received his Diploma Degree and PhD from Universität Konstanz. He is a Fellow of the American Physical Society, the Optical Society of America and the American Association for the Advancement of Science. He is a recipient of the Gentner-Kastler Prize of the Société Française de Physique, Rudolf-Kaiser Award "For pioneering work on atom optics", and the Herbert P. Broida Prize of the APS 2017.

Hide synopsis and biography

Synopsis: Attosecond streaking [1] is the most established technique in attosecond science. Photoelectrons generated by attosecond extreme ultraviolet pulses (XUV), are exposed to a dressing electric field from well synchronized laser pulses. The energy shift experienced by the photoelectrons due to the dressing field is dependent on the delay between the XUV pulse and the dressing field, and makes it possible to measure the respective delay in photoemission between electrons of different type (core electrons vs. conduction band electrons).

While first experiments were performed in noble gases, today’s focus shifted to investigation of electron dynamics in solids, surfaces and layered systems. The information gained in such experiments on tungsten [2] and other solids [3] triggered many theoretical activities leading to different explanations of the delay between various types of electrons. An overview of these measurements will be presented and discussed. Furthermore, we will discuss measurements of time-resolved transport of different types of electrons through a defined number of ad-layers on a bulk material which occurs on an attosecond timescale [4]. While the linear behavior in delay between the different types of electrons can be explained by transport effects, the delay of conduction band electrons is more complex and not fully understood.

Recent experiments on the investigation of electron transport through sub-monolayer structures will additionally be presented.

1. R. Kienberger et al., Nature 427, 817 (2004).
2. A. Cavalieri et al., Nature 449, 1029 (2009).
3. S. Neppl et al., PRL 109 (8), 087401 (2012).
4. S. Neppl et al., Nature 517, 342 (2015).

Biography: Reinhard Kienberger is a professor for experimental physics at the Technical University of Munich (TUM). He received his Ph.D. in quantum optics from the Vienna University of Technology (Austria) in 2002. He spent a year at the Stanford Linear Accelerator Center, Menlo Park, CA, USA. From 2007, he was leader of an independent Junior Research Group at the Max-Planck-Institute of Quantum Optics in Garching/Munich, Germany. Kienberger was awarded the Sofja Kovalevskaja Award of the Alexander von Humboldt Foundation in 2006 and the Starting Grant of the European Research Council (ERC) in 2008. In the same year, he was appointed to TUM, where he became a full professor and the Chair for Laser and X-ray Science. In 2015 he received an ERC Consolidator Grant. He was also awarded the ICO Prize of the International Commission for Optics, the Ernst Abbe Medal of the Carl Zeiss Foundation, and the Prize for Research in Laser Science and Applications, European Physical Society (EPS). He is Member of the European Academy of Sciences and Arts.

Hide synopsis and biography

Synopsis: Atomic and molecular physics was an early beneficiary of the development of electronic computation. Luckily, most of the interactions between electrons and nuclei are well understood and it appears that all that remains is to “turn the crank”. In retrospect, this was not that simple. These are complex many-body systems and in order to overcome the exponential scaling of these computations with the number of particles, clever algorithms and efficient codes needed to be developed. In this talk I will describe a number of the important developments that have taken place over the past four decades and how they have impacted our qualitative and quantitative understanding of scattering processes and the interaction of radiation with matter.

Biography: Barry I. Schneider is a staff member of the National Institute of Standards and Technology (NIST) Applied and Computational Mathematics Division. He received his B.S. in chemistry from Brooklyn College, his M.S. in chemistry from Yale University and a Ph.D. in theoretical chemistry from the University of Chicago. He was a postdoctoral research associate at the University of Southern California (1969-1970), and a staff member of the General Telephone and Electronics Laboratory (1970- 1972). He joined the Theoretical Division of Los Alamos National Laboratory (1972-1991) and then the National Science Foundation (1991-2013 ). In early 2014, he came to NIST as the General Editor of the DLMF project.

Hide synopsis and biography

Synopsis: This lecture will review some of the main theoretical ideas that have proven to be useful in describing the physics of Rydberg atoms and molecules. The basics of multi-channel quantum defect theory will be discussed from a practical point of view, and the description of molecular Rydberg states will also be summarized. This lecture will cover not only some of the basic theoretical ideas, but it will also address some of the phenomenology and motivation for exploring Rydberg systems.

Biography: Chris Greene is the Overhauser Distinguished Professor of Physics at Purdue University. He was an undergraduate at the University of Nebraska at Lincoln, and then received his PhD from the University of Chicago working with Ugo Fano on problems of theoretical atomic physics. Following a postdoctoral stint divided between Richard Zare's group at Stanford and Christian Jungen's group in Orsay, he has held faculty appointments at Louisiana State University and the University of Colorado before he was appointed to his present post. His research into theoretical atomic, molecular, and optical physics has explored multi-channel Rydberg atoms and molecules, ultra-cold few-body physics and physical chemistry, and deals in general with non-perturbative interactions among atoms, electrons, molecules, and/or photons.

Hide synopsis and biography

Synopsis: High-frequency radiation such as extreme ultraviolet (XUV) and x-ray light is ideally suited to observe atoms and molecules changing their natural structure and shape in strong laser fields. For attosecond spectroscopy, high harmonics generated by intense optical lasers are of great use, whereas for x-ray imaging of tiny molecular sizes one can employ coherent femtosecond-pulsed light delivered by free-electron lasers (FELs). In this tutorial, we will cover some recent developments in strong-field intra-atomic and -molecular physics on short time scales which may, at some point in the future, transform synthetic chemistry from the purely classical, population-based thermodynamic realm into the quantum-mechanical domain of phase and amplitude controlled laser-driven reactions.

Biography: Thomas Pfeifer is a Division Director of the Max-Planck Institute for Nuclear Physics (MPIK) in Heidelberg, Germany. He received his M.A. from the University of Texas, Austin in 2000 and his Ph.D. from the University of Würzburg, Germany in 2004. In 2005-2008 he was a Research Fellow (Alexander von Humboldt Foundation) and a Postdoctoral Research Associate at Lawrence Berkeley National Lab (LBNL) and UC Berkeley (Attosecond Chemical Dynamics). In 2009 he became an independent Max-Planck Research Group Leader and in 2014 he was appointed to his present post as the Director of the Experimental Quantum Dynamics&Control Division at the MPIK. In 2013 he received a Heinz-Maier-Leibnitz Award of the German Research Foundation (DFG) and a Consolidator Grant of the European Research Council (ERC) .Thomas Pfeifer’s current research activities are in the field of ultrafast (attosecond/femtosecond) spectroscopy of electronic quantum dynamics in atoms and molecules.

Hide synopsis and biography