Filetype
In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the resonator wavelength can be naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in singlepass linac-based devices, the electron beam is re-circulated in the storage ring and, while the microbunching becomes "thermalized" from turn to turn, the evolution of other bunch
We present a completely ab initio calculation of harmonic generation in xenon exposed to a strong laser field. The time-dependent Schrödinger equation for the atomic response and the propagation equation are numerically integrated yielding excellent agreement with experiment. The weaker variation with pump intensity of the induced dipole in the high-field regime leads to an enormous enhancement in
Generally regarded as a sustainable country, Costa Rica faces the future challenge of maintaining their renewable energy performance amidst climate change impacts and the need to integrate intermittent renewables. This thesis explores the opportunities and barriers for Costa Rica to achieve 100% renewable electricity while maintaining energy security, despite its developing nation status. Through
The modernization of China comes as one of the most interesting topics not only at this moment but also has been researched for a long time. The individualization theories come as a result of modernity. This thesis draws on ten in-depth interviews in order to analyze the individualization among the educated, middle-class young people who were born in the 1990s by testing Yan Yunxiang’s theories of
The polarization direction of an electromagnetic field changes and eventually reaches a steady state when propagating through a birefringent material with off-axis absorption or gain. The steady state orientation direction depends on the magnitude of the absorption (gain) and the phase retardation rate. The change in the polarization direction is experimentally demonstrated in weakly doped (0.05%)
Kärnmagnetisk resonans, NMR, är en teknik som har många användningsområden, inte minst används NMR som en bildgivande teknik för diagnostisering av skador och sjuk- domar, vilket görs med så kallade MR-kameror. Med hjälp av diffusions-NMR kan man mäta vattenmolekylers rörelse, d.v.s. vattnets diffusion. Diffusions-NMR gör det möjligt att mäta hur långt vattenmolekylerna rör sig i olika riktningar.
The Division of Astrophysics is, as of January 2023, a part of the Department of Physics and the astronomy education is now one of the many specializations they offer. Bachelor programmeOnce you decide to join us, to study astronomy and hopefully pursue a career as an astronomer, you start by enrolling to the Bachelor programme in astronomy and astrophysics. After three years of studies you will h
https://www.astro.lu.se/Education - 2026-07-15
Using an eight-band k . p model Hamiltonian with the Burt-Foreman envelope function theory, we have investigated the optical absorption of both linearly and circularly polarized light, as well as related phenomena in InAs/GaSb broken-gap quantum wells grown along the [0 0 1] direction, with emphasis on the effects of electron-hole hybridization and the various symmetry-breaking mechanisms such as
If you wish to continue your studies after your Master’s degree, doctoral studies (PhD studies) may be an option. The doctoral programme entails four years of full time studies and is concluded with a doctoral degree, the most advanced academic qualification awarded in Sweden. The overall aim of the doctoral programme is to train doctoral students to become critical and independent researchers wit
https://www.lusem.lu.se/organisation/department-business-administration/doctoral-studies-business-administration - 2026-07-16
High-dimensional systems are an important frontier for photonic quantum correlation experiments. These correlation tests commonly prescribe measurements with many possible outcomes but they are often implemented through many individual binary-outcome measurements that use only a single-detector. Here, we discuss how this binarization procedure for multioutcome measurements can open a loophole, unl
Summary. Previous data have shown an inter-individual difference in the thrombin generating capacity in vitro as well as phenotypic bleeding pattern among patients with severe haemophilia A (FVIII:C activity below 1%). The reason for this is not known. In addition, there are no reports on how thrombin generation may correlate between siblings. In this study, we evaluated and compared thrombin gene
The optical spectra of a quantum cascade laser structure under nonequilibrium conditions is studied using the technique of nonequilibrium Green functions. We focus on the impact of Coulomb corrections and their dependence on the operating conditions. The role of the static mean field due to the charge distribution by electrons and ioninzed donors is investigated.
Surface states and traps play an important role in the photophysics of colloidal quantum dots. These states typically lead to large red-shifted photoluminescence. We have used steady-state and time-resolved spectroscopic techniques to investigate the nature of the traps and their lifetimes in colloidal CdSe quantum dots. We conclude that at least two different types of traps contribute to the phot
The authors demonstrate operation of a charge readout scheme for quantum dots in a semiconductor nanowire using a quantum point contact defined in a GaAs/AlGaAs two-dimensional electron gas beneath the nanowire. The quantum dots were fabricated by epitaxial growth of InP barriers along a n-type InAs nanowire. Applying negative voltages to two split-gate electrodes aligned to the nanowire induces a
We investigate universal properties of strongly confined particles that turn out to be dramatically different from what is observed for electrons in atoms and molecules. For a large class of harmonically confined systems, such as small quantum dots and optically trapped atoms, many-body particle addition and removal energies, and energy gaps, are accurately obtained from single-particle eigenvalue
The two main design schemes for Terahertz quantum cascade lasers, based on tunnelling and scattering injection, respectively, are theoretically compared. We apply our simulation package based on the non-equilibrium Green’s function technique. Our results provide a good description of the gain degradation with temperature. Thermal backfilling contributes to decrease of population inversion in both
