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Colloidal semiconductor nanocrystals, referred to as quantum dots, offer simple low-temperature solution-based methods for constructing optoelectronic devices such as light emitting diodes and solar cells. We review recent progress in the understanding of photoinduced processes in key components of a certain type of quantum dot solar cells where the dots sensitize a suitable metal oxide, such as Z
Hybrid structures of semiconducting (SM) nanowires, epitaxially grown superconductors (SC), and ferromagnetic-insulator (FI) layers have been explored experimentally and theoretically as alternative platforms for topological superconductivity at zero magnetic field. Here, we analyze a tripartite SM/FI/SC heterostructure but realized in a planar stacking geometry, where the thin FI layer acts as a
Quantum droplets may form out of a gaseous Bose-Einstein condensate, stabilized by quantum fluctuations beyond mean field. Determining the ground state of a rotating binary condensate, we show that multiple singly quantized vortices may form in these droplets at moderate angular momenta in two dimensions. Droplets carrying these precursors of an Abrikosov lattice remain self-bound for certain time
We present a nonperturbative analysis of the power spectrum of energy level fluctuations in fully chaotic quantum structures. Focusing on systems with broken time-reversal symmetry, we employ a finite-N random matrix theory to derive an exact multidimensional integral representation of the power spectrum. The N→ limit of the exact solution furnishes the main result of this study - a universal, par
Entanglement evolution is studied in open systems represented by rings of qubits with the Ising interaction and variously oriented external field and with Markov environments. The effect of thermal or dephasing environment is manifested as exponential decrease of the entanglement superposed on its dynamics in the isolated system. (C) 2009 Elsevier B.V. All rights reserved.
The main theme of this review is the many-body physics of vortices in quantum droplets of bosons or fermions in the limit of small particle numbers. Systems of interest include cold atoms in traps as well as electrons confined in quantum dots. When set to rotate, these in principle different quantum systems show remarkable analogies. The topics reviewed include the structure of the finite rotating
This dissertation deals with the optical properties of Quantum Cascade Lasers (QCLs). Studies are performed using transport calculations employing the theory of Non-Equilibrium Green's Functions, and screening is studied within the Random Phase Approximation. Focus is put on the temperature dependent effects in THz QCLs. After a popular science summary and a presentation and discussion of the the
Popular Abstract in Swedish Den här avhandlingen handlar om hur kristaller, som innehåller en liten mängd av ämnen tillhörande gruppen sällsynta jordartsmetaller, kan användas för forskning och tillämpningar rörande kvantinformation. Genom att belysa kristallerna med laserljus kan atomernas tillstånd styras och studeras. I avhandlingen diskuteras olika aspekter av hur de sällsynta jordartsatomer sThis thesis describes investigations of the use of cryogenically cooled rare-earth-ion-doped crystals for quantum information processing and quantum optics. Several aspects of the coherent interaction between light and rare-earth ions in solids are addressed. Quantum information science has given physicists new views of quantum mechanics. The transmission of quantum states has already found pract
Semiconductor nanostructure based devices provide new opportunities for contributing to a sustainable energy usage. This includes harvesting of energy (solar cells) and saving of energy, e.g. in lighting (light-emitting diodes, LEDs) and transfer of energy (power devices). However, development and improvement of nanostructure devices requires thorough characterization and understanding on a singleSemiconductor nanostructure based devices provide new opportunities for contributing to a sustainable energy usage. This includes harvesting of energy (solar cells) and saving of energy, e.g. in lighting (light-emitting diodes, LEDs) and transfer of energy (power devices). However, development and improvement of nanostructure devices requires thorough characterization and understanding on a single
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
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
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
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
