02.10.2007 13:30	High numerical aperture polarization optics
Prof. Gerd Leuchs Friedrich-Alexander-Universität Erlangen-Nürnberg Max-Planck-Forschungsgruppe f. Optik, Information und Photonik, Erlangen
Abstract: The vector properties of the light field become important in optical systems with large opening angles. Novel developments in polarization control led to a new field: High numerical aperture polarization optics. Specific scenarios are focusing, imaging and the optimized coupling of the light field to an antenna in free space, such as the coupling between a photon and an atom. Prof. Gerd Leuchs Homepage
09.10.2007 13:30	Coherent control with shaped photons
Prof. Yaron Silberberg Weizmann Institute of Science, Israel
Abstract: Quantum coherent control is an elegant method for driving quantum systems through clever application of quantum interferences. The most successful experimental approach to date has used shaped femtosecond pulses as the driving field. Starting with simple examples of atomic systems, I shall demonstrate how pulse shaping can be applied to control such systems in nontrivial, often surprising ways, even though the quantum levels are many orders of magnitude narrower than the light spectrum. I shall then discuss how control can be extended to nonclassical light, and in particular show how one can use pulse shaping tools on single-photon sources. Photon shaping can add a new twist to the toolbox of quantum information. Prof. Yaron Silberberg
16.10.2007 13:30	Optical clock with a single trapped Ytterbium ion
Dr. habil. Ekkehard Peik Physikalisch-Technische Bundesanstalt Braunschweig
Abstract: Laser spectroscopy of trapped, laser-cooled ions can now resolve forbidden transitions with a linewidth of a few hertz. These systems will be used as optical atomic clocks that offer higher stability and greater accuracy than the best primary caesium clocks available today. We investigate an optical clock based on an electric quadrupole transition at 688 THz in the Yb+ ion and have shown that the frequencies realized in two independent ion traps agree to within a few parts in 10^16. We prepare to observe the electric-octupole transition of Yb+ at 642 THz with sub-hertz resolution. Repeated measurements of the frequency ratio of the 688 THz and 642 THz transitions permit to search for temporal variations of the fine structure constant with high sensitivity.
23.10.2007 13:30	Atom-photon entanglement
Prof. Harald Weinfurter LMU München und MPQ, Garching
30.10.2007 13:30	Bose-Einstein condensation meets cavity QED
Prof. Tilman Esslinger Eidgenössische Technische Hochschule, Zürich
Abstract: Cavity quantum electrodynamics (cavity QED) has proven to be exceedingly successful in illuminating matter-light interaction and in providing a platform to test ideas for quantum information processing. In this talk I will report on the strong coupling of a Bose-Einstein condensate to the quantized field of an ultrahigh-finesse optical cavity. The experiment brings us into a conceptually new regime of cavity QED where all atoms occupy a single mode of a matter-wave field and couple identically to the light, sharing a single excitation. Prof. Tilman Esslinger
05.11.2007 13:30	Intricate Dynamics of quantum dot nuclear spins in low and high magnetic fields Location: Theory seminar room - B 2.46
Patrick Maletinsky ETH Zürich
06.11.2007 13:30	Field-induced time-resolved effects of electronic rearrangements in atoms
Prof. Cleanthes Nicolaides Technische Universität, Athen
Abstract: A fundamental issue in modern Atomic, Molecular and Optical Physics is the possibility of solving from first principles the time-dependent Schrödinger equation (TDSE) for poly-electronic atoms and molecules in arbitrary states interacting with one or more electromagnetic pulses. I will discuss key aspects of perturbative and of nonperturbative approaches to this goal, yielding analytic as well as numerical results for time-resolved quantities in many-electron systems. The essential element of this approach is the development of formalism and methods that utilize physically relevant state-specific wavefunctions of stationary states of the discrete and the continuous spectrum. Some of the prototypical examples of applications involve pump-probe excitation schemes of multiply excited states with hypershort time delays, or the hyperfast coherent excitation and decay of nonstationary multiply or inner-hole excited states exhibiting effects that are caused by the rearrangement of strongly correlating electrons, e.g. [1]. It is computed that the duration of such rearrangements is of the order of a few femtoseconds down to a few hundred attoseconds. [1] Th. Mercouris, Y. Komninos and C. A. Nicolaides, Phys. Rev. A76, 033417 (2007)
13.11.2007 13:30	A quantum degenerate Fermi-Fermi-Bose mixture Double Feature
Matthias Taglieber Max-Planck-Institut für Quantenoptik, Garching
Abstract: We report on the generation of a quantum degenerate Fermi-Fermi mixture of two different atomic species. The quantum degenerate mixture is realized employing sympathetic cooling of fermionic 6Li and 40K gases by an evaporatively cooled bosonic 87Rb gas. We describe the combination of trapping and cooling methods that proved crucial to successfully cool the mixture. In particular, we study the last part of the cooling process and show that the efficiency of sympathetic cooling of the 6Li gas by 87Rb is increased by the presence of 40K through catalytic cooling. Due to the differing physical properties of the two components, the quantum degenerate 6Li-40K Fermi-Fermi mixture is an excellent candidate for a stable, heteronuclear system allowing to study several so far unexplored types of quantum matter. Matthias Taglieber
13.11.2007 14:00	Quantum atom optics Double Feature
Ingrid Schuster Max-Planck-Institut für Quantenoptik, Garching
Abstract: Placing an atom between two highly reflecting mirrors not only changes the radiative properties of the atom, but the strong coupling of the atom to a light mode also results in a system with new characteristics. One of those is the occurrence of new multi-photon resonances, which respond nonlinearly on the probe intensity, even in the low-saturation limit. While the normal-mode resonances, also known as vacuum Rabi splitting, can be explained classically by linear dispersion theory, these resonances are a direct consequence of the quantization of the optical field. We observe a two-photon resonance in the spectrum of a strongly-coupled atom-cavity system and show evidence for its nonlinear intensity response.
20.11.2007 13:30	Unified Modelling for Laser Optics
Prof. Frank Wyrowski University of Jena and LightTrans GmbH
27.11.2007 15:00	Risikomessung und Absicherung Start 15:00 Uhr
Dr. Ulrich Spreitzer BELTIOS GmbH
Abstract: With topics as Basel II or solvency II, risk (measure) is of interest; but risk is not well defined. Is it equivalent to insolvency, loss, uncertainty or even volatility (s)? Artzner et al*. showed, that risk (within finance) has to be discussed not in terms of changes between two dates (s) but in terms of future values as done within Basel II and Solvency II as capital at risk. With W as a finite set of states of nature, X as random variable of future net worth, G (risk) as set of all real valued functions of R (W is finite; Rn ) we have r (measure of risk) as a mapping from G into R. But BAFIN or BMF and also every fund manager does some limitations on G ; i.e. he selects his own measure of risk. We will show effects of these different measures of risk and how to safeguard risk on portfolio optimisation, evaluate risk capital and also we will ask for analogue problems within physics. *Artzner P., Delbaen F.,Eber J.-M., Heatz D., Math. Finance 9 (1999), 3 203-228
04.12.2007 13:30	Nuclear spins in quantum dots. A mesoscopic system for quantum information processing? Double Feature
Dr. Geza Giedke Max-Planck-Institut für Quantenoptik, Garching
Abstract: Electron spins in semiconductor quantum dots are intensively studied as a possibly scalable implementation for quantum information processing (QIP). The strongest intrinsic coupling affecting electron spins in these systems is the hyperfine interaction with the lattice nuclei. This is a source of errors for the implementation of spin qubits, but also opens the way to study a single well-localized and isolated mesoscopic quantum system and interesting applications. We study ways to polarize, measure, and manipulate the nuclear spin ensemble. We show how cavity-QED-like dynamics emerges in the limit of high polarization. Some QIP applications are discussed. Dr. Geza Giedke
04.12.2007 14:00	Picosecond electron deflectometry of optical-field ionized plasmas Double Feature
Peter Reckenthäler Max-Planck-Institut für Quantenoptik, Garching
Abstract: We demonstrate a new method of investigating optical field ionized (OFI) plasmas which allows their dynamics to be studied with ultrahigh temporal resolution and yields information not accessible by other methods. Ultrashort electron pulses with an energy of 20 keV are directed onto an OFI nitrogen plasma generated by a 50 fs titanium-sapphire laser pulse. Deflection of the electrons by the fields resulting from charge separation yields images of the expanding plasma. Pump-probe experiments of the plasma expansion capture changes within a few picoseconds with high spatial resolution. Analysis of the images reveals features not seen in previous studies: an expanding cloud of relatively hot electrons and electron lobes at the entrance and exit of the laser. Peter Reckenthaeler
11.12.2007 13:30	Coherent Chemistry without Light: Atom-Molecule Oscillations Induced by a Static Magnetic Field
Dr. Nils Syassen Max-Planck-Institut für Quantenoptik, Garching
Abstract: When two atoms scatter off one another, they temporarily populate molecular bound states. Usually this happens with rather low probability but this process can be resonantly enhanced by applying a static magnetic field. We experimentally study this process with an unusual boundary condition, namely in an optical lattice where each lattice site is occupied by exactly two atoms which in some sense permanently scatter off each other. Here, the application of the magnetic field leads to sinusoidal oscillations between the atomic and the molecular state during which a molecule fraction of almost 100% is reached.
14.12.2007 00:00	From negative refraction to single photon control: New frontiers in quantum coherence Special Seminar
Susanne Yelin University of Connecticut
Abstract: Quantum coherence effects such as electromagnetically induced transparency can be used for a multitude of linear and nonlinear optics. I will introduce two novel applications in order to demonstrate potential uses of these ideas: First, how to electromagnetically induce chirality and how to use it to create media with negative refraction, as needed, for example, for the so-called "superlens"? Second, how can one utilize the long-range interaction of dipolar molecules to create a quantum computer based on either single particles or molecular ensembles?
17.12.2007 00:00	Controlling single nuclei and lighting nanowires: new frontiers of quantum optical science Special Seminar
Prof. Mikhail Lukin Harvard University, Cambridge, Physics Department
Abstract: Controlling quantum behavior of light and matter is an outstanding challenge in modern science and engineering. It is at the heart of many modern developments in an emerging interface involving quantum optics and quantum information science, mesoscopic physics, nano-science and many-body physics of strongly correlated systems. Two examples of these developments, will be described in this talk. Specifically, we will discuss our recent work involving the controlled manipulation of individual nuclear spins in a high-purity diamond lattice. Our approach combines ideas from single molecule spectroscopy, quantum optical control techniques and the physics of mesoscopic spin ensembles. It allows us to isolate, polarize and manipulate single nuclear spins and use them to create quantum memory and small quantum registers with exceptional coherence properties, even under ambient room temperature conditions. We will also describe a novel approach to controlling light-matter interactions that make use of sub-wavelength localization of optical fields on metallic nano-sized wires. This approach combines the ideas of quantum optics with those of electronics and plasmonics. We show that it can be used to create an efficient quantum interface between individual optical emitters and individual surfaces plasmons. Looking forward, we will describe novel applications of these techniques. These include single photon nonlinear optics and strongly interacting many-body systems of photons, new approaches to quantum communication and computation as well as new quantum magnetic sensors with nanoscale resolution.
18.12.2007 13:30	Cold atoms in Flatland
Prof. Jean Dalibard École Normale Supérieure, Paris
Abstract: Coherence and superfluidity are hallmark properties of cold quantum matter. With the achievement of Bose-Einstein condensation and fermionic superfluidity in atomic gases, it is now possible to study these phenomena in a clean and well controlled environment. The possibility to engineer the trapping geometry and the strength of interactions provides a way to simulate the rich dynamics of condensed-matter systems. The investigation of low dimension gases is of particular interest in this context, since the phase transitions that a system can undergo depends crucially on its dimensionality. The talk will review recent progresses in this direction, and address in particular the specific properties of 2D atomic gases. The key role played by quantized vortices will be emphasised and connections with other domains of macroscopic quantum physics, such as Quantum Hall phenomena, will be discussed.

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