Archiv 2016

Raum: Seminar Room I-III, EG.076-080

Kwang S. Kim - Carbon based nano-optics, -electronics and -spintronics

Hamburg Photon Science Colloquium
I discuss the interplay between theory and experiment to design super functional carbon-based nanomaterials/nanodevices. These include intriguing organic nanostructures, graphene and functionalized carbon hybrid materials for energy harvesting, solar cells, fuel cells, gas storage, water remediation and medical treatment. Hyperresolution phenomena by nano-lensing, super-paramagnetism driven water remediation, and super-magnetoresitance & ultrafast DNA sequencing of graphene nanoribbon are addressed. [mehr]

Annual General Meeting at MPSD


Hermann Dürr - Controlling spins in space and time

Hamburg Photon Science Colloquium
Magnetism is a quantum effect that has fascinated mankind for millennia and also led to many modern-day applications, very prominently in information processing and storage. Now available polarized soft X-ray pulses from X-FELs with sub-100 fs duration allow observing magnetic interactions at work in their natural length and timescales. I will show how the challenges for performing time-resolved XMCD at the Linac Coherent Light Source have recently been overcome and give an overview how such studies help to understand the fundamental speed limits for nanoscale spin motion. [mehr]

Thomas Ebbesen - The Alchemy of Vacuum – Hybridizing Light and Matter

Hamburg Photon Science Colloquium
Strong coupling of light and matter can give rise to a multitude of exciting physical effects through the formation of delocalized hybrid light-matter states. After introducing the fundamental concepts, examples of modified properties under strong coupling, such as enhanced charge transport in organic semiconductors and non-radiative energy transfer, will be given to illustrate the broad potential of light-matter states. [mehr]

Horst Weller - Nanocrystals in materials and life science applications

Hamburg Photon Science Colloquium
Nanocrystals are already used for many applications in technical products for everyday life. The talk will describe actual developments such as quantum dots in display and lighting technology, ultra-hard nanocomposite materials and materials for the visualization of biological events or malignant cells or tissues. Different chemical approaches and factors determining the biological response on fully synthetic nanocrystals will be reported. We will present approaches to improve targeting specificity and concepts to optimize physical proper ties to increase the sensitivity for imaging. [mehr]

Ulrich Schollwöck - Disentangling strongly correlated Quantum Systems

CFEL Theory Seminar
Strongly correlated quantum systems, where more traditional methods of quantum many-body physics fail, have attracted enormous attention over the last decades but still provide formidable problems for our understanding: High-Tc superconductors, frustrated quantum magnets, transition metal oxide and rear earth materials, ultracold atomic gases in optical lattices. Key numerical advances have been made using so-called tensor network methods, the best known of which is the density matrix renormalization group (DMRG). After an introduction into the methodology, I want to presentselected results from areas which in my view present particularly interesting challenges also in the future: non-equilibrium dynamics of correlated systems (here: ultracold atoms in lattices) and material properties of threedimensionaltransition metal oxides. [mehr]

Kerry Vahala - Towards integrated optical clocks & frequency comb spectroscopy systems

Hamburg Photon Science Colloquium
Like a tuning fork for light, optical resonators have a characteristic set of frequencies at which it is possible to confine light waves. At these frequencies, optical energy can be efficiently stored for lengths of time characterized by the resonator Q factor, roughly the storage time in cycles of oscillation. In the past there has been remarkable progress in boosting optical storage time in micro and millimeter-scale optical resonators with Q factors exceeding 100 billion. This opens up new opportunities to access a wide range of nonlinear phenomena and to create laser devices operating at low power. After reviewing the nonlinear physics of these devices, current efforts to miniaturize time standards and stable frequency sources for metrology and spectroscopy will be described. [mehr]

Faster than a Cycle of Light

Hamburg Photon Science Colloquium
Watching a single molecule move on its intrinsic time scale has been a dream of modern nanoscience. We show how a single oscillation cycle of phase-stable infrared pulses can accelerate and recollide electrons in solids. By combining this idea with sub-angstrom spatial resolution of scanning tunnelling microscopy we manage to control the ultrafast quantum motion of individual electrons in a single orbital of one molecule. Such elementary quantum processes allow us to record first slow-motion movies of individual vibrating molecules. [mehr]
CUI invites to its fourth International Symposium on Thursday, 10 November 2016, in the Center for Free Electron Laser Science. In honor of the winner of this year’s Hamburg Prize for Theoretical Physics the symposium will cover modern trends in condensed matter physics. The prize is worth 40 000 Euro and will be presented by the Joachim Herz Stiftung together with CUI to Russian physicist Mikhail Katsnelson. [mehr]

Nanomembrane Devices: from Concepts to Applications

Hamburg Photon Science Colloquium
Nanomembranes are thin, flexible, transferable and can be assembled into 3D micro- and nanoarchitectures. This makes them attractive for a broad range of applications and scientific research fields ranging from strain-tunable heterostructure devices to ultra-compact 3D systems both on and off the chip. Rolled-up nanomembranes can be exploited to rigorously compact electronic circuitry, create novel optical components and open up pathways towards entirely new biomedical applications. [mehr]

Model systems in heterogeneous catalysis at the atomic scale

Hamburg Photon Science Colloquium
Our understanding of heterogeneous catalysis is to a large extent based on the investigation of metal single crystals as models. Increasing the complexity of the models, resembling a real disperse metal catalyst, allows one to catch some of the complexity that cannot be covered by metal single crystals alone. We have developed model systems based on metal deposits on single crystalline oxide films, which may be studied at the atomic level using the tools of surface science. [mehr]

It's All About Water

Hamburg Photon Science Colloquium
Ultrafast vibrational spectroscopy can tell a lot about molecular dynamics. Quite diverse examples will be discussed, highlighting the importance of water as a very special substance: the ultrafast dynamics of bulk water and concentrated salt solution studied by THz photon echo spectroscopy, the catalytic cycle of an artificial photosynthetic system for light-driven water splitting, and the response of an allosteric protein whose dynamics is dictated by the water solvation layer. [mehr]

Nele Müller - Electron diffraction and controlled molecules


Plasmon-Enhanced Raman Scattering

Hamburg Photon Science Colloquium
Plasmons are the collective excitations of free electrons. They focus light into nanoscale volumes, increasing electromagnetic fields by orders of magnitude. Plasmonic enhancement in light scattering (SERS) leads to a 10⁸ increase in the cross section. I will present Raman measurements on graphene and nanotubes coupled to nanoplasmons. The enhancement will be described as a higher-order Raman process with striking consequences for our understanding of plasmon-matter interaction at the nanoscale. [mehr]

Electronic and Structural Dynamics in Solids: A Momentum-Resolved View on Microscopic Coupling and Correlation Phenomena

MPSD Seminar
The coupling and mutual dependence of electronic and vibrational degrees of freedom is at the heart of microscopic as well as macroscopic phenomena in condensed matter. Ultrafast pump-probe techniques provide experimental access to these coupling and correlation effects by revealing the response of electrons and lattice to specific excitation of a material. [mehr]

Testing Fundamental Physics with Cold Atoms and Molecules

Hamburg Photon Science Colloquium
Cold and ultracold molecules provide a sensitive way to search for new physics, e.g. variation of fundamental constants, dark energy, or new elementary particles. I will describe some of these ideas, with particular emphasis on the search for a permanent electric dipole moment of the electron, which already provides a strong constraint on possible supersymmetric theories of particle physics. Laser cooling can now be applied to molecules. I will discuss the recent advances in that area and the extraordinary sensitivity that this new approach can bring to tests of fundamental physics. [mehr]

Networked Quantum Information Technologies

Hamburg Photon Science Colloquium
Hybrid light-matter networks offer the promise for delivering robust quantum information processing technologies, from sensor arrays to secure communications to quantum simulators and eventually to a quantum computer. Photonics plays a major role in delivering these new enhanced performance applications. I will describe recent science and engineering progress towards build a resilient, scalable photonic quantum network. [mehr]

Ultrafast Electron Kinetics in Graphene

Hamburg Photon Science Colloquium
Graphene is an ideal material to study new processes in the ultrafast carrier kinetics of a two-dimensional system: Its linear energy dispersion and the vanishing bandgap allow new and surpising electron scattering processes, suppressed in conventional semiconductors: A typical, fascinating example is a process which generates two optically excited electrons out of one photon. [mehr]

Why Water is weird

Hamburg Photon Science Colloquium
All life on Earth needs water to survive. But increasingly it seems that the characteristics that make water a solvent for life are also those that make it the weirdest of liquids. Some of these quirks of ‘life’s matrix’ are well understood; others are still being debated, sometimes furiously and controversially. I will explore what we do and don’t know about water, ending with a consideration both of how its behaviour in living cells can offer clues for new purification technologies and of whether its unique role for life on Earth makes it a prerequisite for life on other worlds. [mehr]

Water: from ab-initio simulations to coarse grained models

Hamburg Photon Science Colloquium
The unusual properties of water, including the thermodynamic anomalies of the liquid, the existence of more than one amorphous ice form, and the abnormal mobility of the water ions, derive from the tetrahedral network of hydrogen bonds that hold the molecules together. Computer simulations are an essential tool to understand the microscopic origin of these fascinating properties, complementing experiment and theory. [mehr]

Theoretical challenges: simulating materials out of equilibrium

MPSD Theory Workshop
The workshop covers advances and challenges in the simulation of materials and the description of light-matter interactions in molecules and solids. [mehr]

Designing New Materials for Solar Energy Conversion

Hamburg Photon Science Colloquium
After introducing general aspects of photovoltaics this talk will illustrate how spectroscopy with soft X-rays can help developing new materials and new designs for solar cells. Starting with the most general layout of a solar cell, the focus will be on combining its three components with atomic precision into one molecular complex. A dream experiment will be discussed where the movement of photo-generated carriers through such a complex is tracked in real time at the latest X-ray sources. [mehr]

Quantum Magnetism with Ultracold Atoms

Hamburg Photon Science Colloquium
Ultracold atoms in optical lattices form a versatile platform for studying many-body physics, with the potential of addressing some of the most important issues in strongly correlated matter. I will present experimental results on the characterization of the BEC-BCS crossover with ultracold atoms, the phases of a spin-imbalanced Fermi gas in one and three dimensions, and finally the detection of anti-ferromagnetic order in the 3D Hubbard model, a paradigm model of strong correlations. [mehr]

From Materials Science to Basic Physics

Hamburg Photon Science Colloquium
Condensed matter provides us deep insights into quantum physics. Giving just two examples, wave-corpuscle duality manifests itself in spectroscopy of strongly correlated systems as coexistence of itinerant and atomic-like features, and graphene and other Dirac materials provide a natural playground to study vacuum reconstruction, Klein tunneling and other fundamental quantum relativistic phenomena. Electron-photon interaction is the key tool to understand this rich and nontrivial physics. [mehr]

Squeezed Light and the Detection of Gravitational Waves

Hamburg Photon Science Colloquium
Laser light with a 'squeezed' quantum uncertainty shows less quantum noise and allows for improved optical measurements. The most prominent example is the use of squeezed light in gravitational wave detectors. Soon, also LIGO will be equipped with squeezed light. In principle, it allows for ultra-sensitive measurements in the so-called quantum non-demolition regime. But what is squeezed light, how is it produced and what are its other potential applications? This talk will answer these questions. [mehr]

Simulating Neutron Stars in the Laboratory

Hamburg Photon Science Colloquium
Our Universe displays a vast panoply of exotic objects like the Earth, black holes, or neutron stars. With a mass of twice the Sun mass and a radius of ~10 km, a neutron star is a very dense object. At a temperature of 10^8 K, the spin 1/2 neutrons are believed to be in a superfluid state. We will show how dilute gases prepared by laser techniques at the other extreme of the temperature scale, in the Nano kelvin range, can help us to understand the superfluid state of neutron stars. [mehr]

Ultracold fermions: From „high Tc“ to „ultrafast“

Hamburg Photon Science Colloquium
Fermionic quantum matter is ubiquitous in nature and has many technological applications. After a general introduction into the physics of ultracold fermionic quantum gases, the talk will highlight two striking examples. Superfluidity in Fermi gases has been subject of intense research for more than a decade with many spectacular observations. Recent work has provided unique access to quasiparticles in the Landau-Fermi liquid regime, whose fast dynamics can now be observed on the Fermi time scale. [mehr]

Stimulation of Quantum Phases by Time-Dependent Perturbations

Hamburg Photon Science Colloquium

New Mechanistic Insights into Virus Assembly & Evolution

Hamburg Photon Science Colloquium

Surface Dynamics – Real Time Observations of Electronic Structure

Hamburg Photon Science Colloquium
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