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Dissertation
Optimizing Robust Quantum Gates in Open Quantum Systems
(2015-05-27)
We are currently at the cusp of a revolution in quantum technology that relies not just on the passive use of quantum effects, but on their active control. At the forefront of this revolution is the implementation of a quantum computer. Encoding information in quantum states as “qubits” allows to use entanglement and quantum superposition to perform calculations that are infeasible on classical computers. The fundamental challenge in the realization of quantum computers is to avoid decoherence – the loss of quantum ...
Aufsatz
Asymptotic model for shape resonance control of diatomics by intense non-resonant light: universality in the single-channel approximation
(2015)
Non-resonant light interacting with diatomics via the polarizability anisotropy couples different
rotational states and may lead to strong hybridization of the motion. The modification of shape
resonances and low-energy scattering states due to this interaction can be fully captured by an
asymptotic model, based on the long-range properties of the scattering (Crubellier et al 2015 New J.
Phys. 17 045020). Remarkably, the properties of the field-dressed shape resonances in this asymptotic
multi-channel description ...
Aufsatz
Asymptotic model for shape resonance control of diatomics by intense non-resonant light
(2015)
We derive a universal model for atom pairs interacting with non-resonant light via the polarizability
anisotropy, based on the long range properties of the scattering. The corresponding dynamics can be
obtained using a nodal line technique to solve the asymptotic Schrödinger equation. It consists of
imposing physical boundary conditions at long range and vanishing the wavefunction at a position
separating the inner zone and the asymptotic region. We show that nodal lines which depend on the
intensity of the ...
Aufsatz
Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion
(2015)
A Ramsey-type interferometer is suggested, employing a cold trapped ion and two time-delayed offresonant
femtosecond laser pulses. The laser light couples to the molecular polarization anisotropy,
inducing rotational wavepacket dynamics. An interferogram is obtained from the delay dependent
populations of the final field-free rotational states. Current experimental capabilities for cooling and
preparation of the initial state are found to yield an interferogram visibility of more than 80%. The
interferograms can ...
Dissertation
Magneto-optische Oberflächenplasmonresonanzeffekte in austauschverschobenen Dünnschichtsystemen
(2015-08-17)
Die Wechselwirkungen zwischen Biomolekülen spielen eine zentrale Rolle in der biochemischen und pharmazeutischen Forschung. In der biomolekularen Interaktionsanalyse sind dabei Biosensoren auf Basis des Oberflächenplasmonresonanzeffekts (SPR-Effekt) weitverbreitet. Seit Einführung der ersten kommerziellen SPR-Biosensoren Anfang der 1990er Jahre wurden verschiedenste Messanordnungen sowie Materialsysteme mit dem Ziel einer möglichst hohen Empfindlichkeit getestet. Eine Möglichkeit zur Steigerung der Empfindlichkeit ...
Dissertation
Fabrication of diamond nanostructures and investigation of the imbedded NV centers
(2015-02-24)
Diamant ist ein Material mit vielen außerordentlichen Eigenschaften, die ihn zu einem äußerst vielversprechenden Kandidaten für Anwendungen in Wissen-schaft und Technik machen. In den letzten Jahren wurde Diamant häufig als einzigartige Plattform für neue Anwendungen beispielsweise in der Quanteninformationstechnologie (QIT) oder in der Magnetometrie im Nanometermaßstab eingesetzt, wobei einer der wichtigsten lumineszierenden Gitterdefekte im Diamantgitter eingesetzt wird. Dabei handelt es sich um die sogenannten ...
Dissertation
First-principles electronic theory of non-collinear magnetic order in transition-metal nanowires
(2015-05-27)
The structural, electronic and magnetic properties of one-dimensional 3d transition-metal (TM)
monoatomic chains having linear, zigzag and ladder geometries are investigated in the frame-work of
first-principles density-functional theory. The stability of long-range magnetic order along the
nanowires is determined by computing the corresponding frozen-magnon dispersion relations as a
function of the 'spin-wave' vector q.
First, we show that the ground-state magnetic orders of V, Mn and Fe linear chains at ...
Dissertation
Magnetic interactions between transition metal impurities and clusters mediated by low-dimensional metallic hosts: A first principles theoretical investigation
(2015-03-31)
The magnetic properties and interactions between transition metal (TM) impurities and clusters in low-dimensional metallic hosts are studied using a first principles theoretical method. In the first part of this work, the effect of magnetic order in 3d-5d systems is addressed from the perspective of its influence on the enhancement of the magnetic anisotropy energy (MAE). In the second part, the possibility of using external electric fields (EFs) to control the magnetic properties and interactions between nanoparticles ...
Dissertation
Ab initio Molecular Dynamics Simulations of the Structural Response of Solids to Ultrashort Laser and XUV Pulses
(2015-04-10)
The theoretical model and underlying physics described in this thesis are about the interaction of femtosecond-laser and XUV pulses with solids. The key to understand the basics of such interaction is to study the structural response of the materials after laser interaction. Depending on the laser characteristics, laser-solid interaction can result in a wide range of structural responses such as solid-solid phase transitions, vacuum phonon squeezing, ultrafast melting, generation of coherent phonons, etc. During my ...
Dissertation
Optimierung der laserinduzierten Plasmaspektroskopie an Metallen durch Femtosekunden-Doppelpulse für die Entwicklung eines hochauflösenden 3D-Rasterabbildungsverfahrens
(2015-03-05)
Die laserinduzierte Plasmaspektroskopie (LIPS) ist eine spektrochemische Elementanalyse zur Bestimmung der atomaren Zusammensetzung einer beliebigen Probe. Für die Analyse ist keine spezielle Probenpräparation nötig und kann unter atmosphärischen Bedingungen an Proben in jedem Aggregatzustand durchgeführt werden. Femtosekunden Laserpulse bieten die Vorteile einer präzisen Ablation mit geringem thermischen Schaden sowie einer hohen Reproduzierbarkeit. Damit ist fs-LIPS ein vielversprechendes Werkzeug für die Mikroanalyse ...