Fabrication of mirror templates in silica with micron-sized radii of curvature

We present the fabrication of exceptionally small-radius concave microoptics on fused silica substrates using CO2 laser ablation and subsequent reactive ion etching. The protocol yields on-axis near-Gaussian depressions with radius of curvature $\lesssim5$ microns at shallow depth and low surface roughness of 2 angstroms. This geometry is appealing for cavity quantum electrodynamics where small mode volumes and low scattering losses are desired. We study the optical performance of the structure within a tunable Fabry-Perot type microcavity, demonstrate near-coating-limited loss rates (F = 25,000) and small focal lengths consistent with their geometrical dimensions.Comment: 5 pages, 4 figure

Deterministic enhancement of coherent photon generation from a nitrogen-vacancy center in ultrapure diamond

The nitrogen-vacancy (NV) center in diamond has an optically addressable, highly coherent spin. However, an NV center even in high quality single-crystalline material is a very poor source of single photons: extraction out of the high-index diamond is inefficient, the emission of coherent photons represents just a few per cent of the total emission, and the decay time is large. In principle, all three problems can be addressed with a resonant microcavity. In practice, it has proved difficult to implement this concept: photonic engineering hinges on nano-fabrication yet it is notoriously difficult to process diamond without degrading the NV centers. We present here a microcavity scheme which uses minimally processed diamond, thereby preserving the high quality of the starting material, and a tunable microcavity platform. We demonstrate a clear change in the lifetime for multiple individual NV centers on tuning both the cavity frequency and anti-node position, a Purcell effect. The overall Purcell factor $F_{\rm P}=2.0$ translates to a Purcell factor for the zero phonon line (ZPL) of $F_{\rm P}^{\rm ZPL}\sim30$ and an increase in the ZPL emission probability from $\sim 3 \%$ to $\sim 46 \%$. By making a step-change in the NV's optical properties in a deterministic way, these results pave the way for much enhanced spin-photon and spin-spin entanglement rates.Comment: 6 pages, 4 figure

Epitaxial lift-off for solid-state cavity quantum electrodynamics

We present a new approach to incorporate self-assembled quantum dots into a Fabry-P\'{e}rot-like microcavity. Thereby a 3$\lambda$/4 GaAs layer containing quantum dots is epitaxially removed and attached by van der Waals bonding to one of the microcavity mirrors. We reach a finesse as high as 4,100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor - mirror interface, demonstrating that the epitaxial lift-off procedure is a promising procedure for cavity quantum electrodynamics in the solid state. As a first step in this direction, we demonstrate a clear cavity-quantum dot interaction in the weak coupling regime with a Purcell factor in the order of 3. Estimations of the coupling strength via the Purcell factor suggests that we are close to the strong coupling regime.Comment: 6 pages, 4 figure

Spin dynamics in semiconductors

This article reviews the current status of spin dynamics in semiconductors which has achieved a lot of progress in the past years due to the fast growing field of semiconductor spintronics. The primary focus is the theoretical and experimental developments of spin relaxation and dephasing in both spin precession in time domain and spin diffusion and transport in spacial domain. A fully microscopic many-body investigation on spin dynamics based on the kinetic spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published in Physics Reports

genesis, development and contemporary problems of the concept of human rights

Praca skupia się na tematyce prawa człowieka w kontekście ich ewolucyjności na przestrzeni lat. Pierwsza jej część, dotyczy przede wszystkim historii i genezy rozwoju praw człowieka, które kształtowały się głównie dzięki nurtom filozoficznym i religijnym. W pracy opisane zostały też trzy generacje praw człowieka, których podziału dokonał francuski prawnik Karl Vasak. Trzy generacje, to segregacja praw człowieka przede wszystkim ze względu na uwarunkowania historyczne i tak pierwsza generacja to zbiór praw najstarszych, podstawowych. Generacja druga, to postulaty narodowe podczas ruchów socjalistycznych XIX i XX wieku. Ostatnia generacja to prawa współczesne, związane ściśle z gwałtownymi zmianami następującymi w procesie globalizacji. Ostatnia część pracy dotyka problemów praw człowieka w kontekście współczesnych zjawisk społecznych.This thesis focuses on the topic of humann rights and how it evolved throughout the years. First part deals with the history and genesis of the development of human rights, which have been shaped mainly by philosophical and religious currents. Furthermore, the paper describes three generations of human rights, as devided by french lawyer Karl Vasak. This three generations are devided on the basis of historical background. Therefore, the first generation is the collection of the oldest, basic rights. The second generation consists of national demands during the XIX and XX century socialist movements. The last generation, is the contemporary rights, closesly connected with the exponential changes that accompany the proces of globalization. The last part of the thesis concerns the problems of human rights in the context of contemporary social phenomenons

A small mode volume tunable microcavity: development and characterization

We report the realization of a spatially and spectrally tunable air-gap Fabry-Pérot type microcavity of high finesse and cubic-wavelength-scale mode volume. These properties are attractive in the fields of opto-mechanics, quantum sensing, and foremost cavity quantum electrodynamics. The major design feature is a miniaturized concave mirror with atomically smooth surface and radius of curvature as low as 10 μm produced by CO2 laser ablation of fused silica. We demonstrate excellent mode-matching of a focussed laser beam to the microcavity mode and confirm from the frequencies of the resonator modes that the effective optical radius matches the physical radius. With these small radii, we demonstrate wavelength-size beam waists. We also show that the microcavity is sufficiently rigid for practical applications: in a cryostat at 4 K, the root-mean-square microcavity length fluctuations are below 5 pm

Towards high-cooperativity strong coupling of a quantum dot in a tunable microcavity

We investigate the strong-coupling regime of a self-assembled quantum dot in a tunable microcavity with dark-field laser spectroscopy. The high quality of the spectra allows the line shapes to be analyzed revealing subtle quantum interferences. Agreement with a model calculation is achieved only by including exciton dephasing which reduces the cooperativity from a bare value of 9.0 to the time-averaged value 5.5. In the pursuit of high cooperativity, besides a high Q and low mode-volume cavity, we demonstrate that equal efforts need to be taken towards lifetime-limited emitter linewidths