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We perform an experimental two-color high-order harmonic generation study in argon with the fundamental of an ytterbium ultrashort pulse laser and its second harmonic. The intensity of the second harmonic and its phase relative to the fundamental are varied, in a large range compared to earlier works, while keeping the total intensity constant. We extract the optimum values for the relative phase

With shrinking technologies and higher clock rates comes the possibility to transform multi chip implementations to a single System on Chip (SoC). Implementing clock distribution and limiting the power consumption becomes increasingly troublesome with increased clock rate and chip area. Therefore, designing large Systems on Chip makes it necessary to search for new implementation methods. In this

Pulsed lasers are used for simultaneous single-beam three-dimensional optical trapping of and second-harmonic generation in 50--100-nm nonlinear particles. The emission power of the frequency-doubled light, the trapping stability, and the particle degradation are investigated for KTP and LiNbO3 particles trapped by 25-kHz-repetition-rate Q-switched Nd:YAG and 76-MHz mode-locked Ti:sapphire l a s e

Biophotovoltaic devices modified with immobilized polymeric osmium/azine redox-mediators exhibited a considerable electrical output enhancement (64/43-fold under light/dark conditions, respectively). More importantly, the systems exhibited uninterrupted current generation at same magnitude levels during day/night cycles, paving the way toward solar energy conversion bio-panels that will not requir

Locus-Specific DataBases (LSDBs) store information on gene sequence variation associated with human phenotypes and are frequently used as a reference by researchers and clinicians. We developed the Leiden Open-source Variation Database (LOVD) as a platform-independent Web-based LSDB-in-a-Box package. LOVD was designed to be easy to set up and maintain and follows the Human Genome Variation Society

We present experimental results on high-order harmonic generation in xenon, using a Nd:YAG laser (1064 nm). The harmonic generation efficiency is studied as a function of the laser intensity in the 1013 W/cm2 range. The harmonic conversion rates show a significant change of behavior when the medium becomes ionized (∼1013 W/cm2). This effect can be understood as the change of the nonlinear response

https://www.lu.se/evenemang/mathematical-colloquium-matthias-christandl-university-copenhagen - 2026-07-14

This thesis focuses on electron transport in semiconductor InAs/InP and InSb nanowire quantum devices. However, first the temperature dependence of classical charge transport in InSb nanowire field-effect transistors, FETs, is characterized, using InAs nanowire FETs as a reference. We find that the InSb FETs, in the same way as InAs FETs, are n-type with good current saturation and low voltage ope

The exact diagonalization technique is used to study many-particle properties of interacting electrons with spin, confined in a two-dimensional harmonic potential. The single-particle basis is limited to the lowest Landau level. The results are analysed as a function of the total angular momentum of the system. Only at angular momenta corresponding to the filling factors 1, 1/3, 1/5, etc is the sy

We report preliminary experimental and computational studies of the temporal evolution of the harmonics, generated in xenon, by 50-ps pulses from a Nd: YLF laser, amplified in Nd: glass amplifiers, and focused to produce intensities in the range 1013--5 {\texttimes} 1013 W cm{\textminus}2. Measurements were made of the temporal profiles of the seventh- and ninth-order harmonics using a specially m

In 2015 Jonatan Bohr Brask et al. showed that steady-state entanglement could be generated in two interacting qubits incoherently coupled to thermal baths of different temperatures [1]. This thesis is an attempt to re-evaluate their findings with the hope that a slightly different approach and system can help further our understanding of this not yet well understood phenomena. A Lindblad master eq

This dissertation investigates theoretically electric control of the magnetic properties of molecular magnets. Two classes of magnetic molecules are considered. The first class consists of molecules that are spin frustrated. As a consequence of the frustration, the ground-state manifold of these molecules is characterized by states of different spin chirality, which can be coupled by an external e

The possibility of engineering artificial Kitaev chains in arrays of quantum dots coupled via narrow superconducting regions has emerged as an attractive way to overcome the disorder issues that complicate the realization and detection of topological superconducting phases in other platforms. Although a true topological phase would require long chains, a two-site chain realized in a double quantum

Ljus består av elektromagnetiska vågor som pulserar genom universum med olika frekvenser. Vanligt ljus, som det som kommer från solen och från våra lampor, innehåller ett spektrum av många olika frekvenser. De olika vågornas toppar och dalar svänger inte heller i takt, utan är förskjutna i förhållande till varandra. I laserljus däremot, svänger alla vågor samtidigt upp och ner och med samma frekveThis thesis adresses modeling of quantum cascade lasers using non-equilibrium Green’s functions. Focus lies on the quantitative modeling of the gain when the systems are exposed to strong laser fields, as under realistic opertional conditions. In the first part, an introduction to the general concepts is provided, together with a discussion on approximate analytic expressions. The second part cons

The interplay between superconductivity and the Kondo effect has stimulated significant interest in condensed matter physics. They compete when their critical temperatures are close and can give rise to a quantum phase transition that can mimic Majorana zero modes. Here, we have fabricated and measured Al-InSb nanowire quantum dot-Al devices. In the Kondo regime, a supercurrent-induced zero-bias c

Majorana modes can be engineered in arrays where quantum dots (QDs) are coupled via grounded superconductors, effectively realizing an artificial Kitaev chain. Minimal Kitaev chains, composed by two QDs, can host fully localized Majorana modes at discrete points in parameter space, known as Majorana sweet spots. Unlike grounded superconductors, where the superconducting phase is a conserved quantu

Measuring the thermopower of a confined quantum system reveals important information about its excitation spectrum. Our simulations show how this kind of transport spectroscopy is able to extract a clear signal for the onset of Wigner localization in a nanowire segment. This demonstrates that thermopower measurements provide a tool for investigating complex many-body quantum effects, which is less