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

A coherent light-matter interface with a semiconductor quantum dot in an optical microcavity

The strong-coupling regime of cavity-quantum-electrodynamics (cQED) represents the light-matter interaction at the fully quantum level. Adding a single photon shifts the resonance frequencies, a profound nonlinearity. cQED is a test-bed of quantum optics and the basis of photon-photon and atom-atom entangling gates. At microwave frequencies, success in cQED has had a transformative effect. At optical frequencies, the gates are potentially much faster; the photons can propagate over long distances; and the photons can be detected easily, ideal features for quantum networks. Following pioneering work on single atoms, solid-state implementations using semiconductor quantum dots are emerging, an important prospect for quantum technology. We present here a gated, ultralow-loss microcavity-device which forms a highly coherent photon$-$quantum-dot interface with a cooperativity of $C=150$. The gates allow both the quantum dot charge state and resonance frequency to be controlled electrically; crucially, they eliminate the noise-source which has complicated quantum dot cQED in the past $-$ scattering from the bare microcavity mode even at the quantum dot-microcavity resonance. Even in the microcavity, the quantum dot has a linewidth close to the radiative limit. In addition to a very pronounced avoided-crossing in the spectral domain, we observe a clear coherent exchange of a single energy-quantum between the ``atom" and cavity in the time domain (vacuum Rabi-oscillations). Decoherence arises predominantly via the atom and photon loss-channels. The coherence is exploited to probe the transitions between the singly- and doubly-excited photon-atom system via photon-statistics spectroscopy. We propose this system as a platform for quantum technology, for instance a photon-photon entangling gate

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

Suppression of Surface-Related Loss in a Gated Semiconductor Microcavity

We present a surface-passivation method that reduces surface-related losses by almost 2 orders of magnitude in a highly miniaturized GaAs open microcavity. The microcavity consists of a curved dielectric distributed Bragg reflector with radius of approximately 10 ?m paired with a GaAs-based heterostructure. The heterostructure consists of a semiconductor distributed Bragg reflector followed by an n-i-p diode with a layer of quantum dots in the intrinsic region. Free-carrier absorption in the highly -n-doped and highly -p-doped layers is minimized by our positioning them close to a node of the vacuum electromagnetic field. The surface, however, resides at an antinode of the vacuum field and results in significant loss. These losses are much reduced by surface passivation. The strong dependence on wavelength implies that the main effect of the surface passivation is to eliminate the surface electric field, thereby quenching below-band-gap absorption via a Franz-Keldysh-like effect. An additional benefit is that the surface passivation reduces scattering at the GaAs surface. These results are important in other nanophotonic devices that rely on a GaAs-vacuum interface to confine the electromagnetic field

A bright and fast source of coherent single photons

A single photon source is a key enabling technology in device-independent quantum communication, quantum simulation for instance boson sampling, linear optics-based and measurement-based quantum computing. These applications involve many photons and therefore place stringent requirements on the efficiency of single photon creation. The scaling on efficiency is an exponential function of the number of photons. Schemes taking full advantage of quantum superpositions also depend sensitively on the coherence of the photons, i.e. their indistinguishability. It is therefore crucial to maintain the coherence over long strings of photons. Here, we report a single photon source with an especially high system efficiency: a photon is created on-demand at the output of the final optical fibre with a probability of 57%. The coherence of the photons is very high and is maintained over a stream consisting of thousands of photons; the repetition rate is in the GHz regime. We break with the established semiconductor paradigms, such as micropillars, photonic crystal cavities and waveguides. Instead, we employ gated quantum dots in an open, tunable microcavity. The gating ensures low-noise operation; the tunability compensates for the lack of control in quantum dot position and emission frequency; the output is very well-matched to a single-mode fibre. An increase in efficiency over the state-of-the-art by more than a factor of two, as reported here, will result in an enormous decrease in run-times, by a factor of $10^{7}$ for 20 photons.Comment: Main text: 5 pages (including 4 figures), Supplementary Information: 8 pages (including 7 figures

Modular Synthesis of Semiconducting Graft Co-polymers to Achieve "clickable" Fluorescent Nanoparticles with Long Circulation and Specific Cancer Targeting

Semiconducting polymer nanoparticles (SPNs) have been explored for applications in cancer theranostics because of their high absorption coefficients, photostability and biocompatibility. However, SPNs are susceptible to aggregation and protein fouling in physiological conditions, which can be detrimental for in vivo applications. Here, we describe a method for achieving colloidally stable and low-fouling SPNs by grafting PEG onto the backbone of the fluorescent semiconducting polymer, poly(9,9'-dioctylfluorene-5-fluoro-2,1,3-benzothiadiazole) (F8BT-F), in a simple one-step substitution reaction, post-polymerisation. Further, by utilising azide-functionalised PEG we site-specifically "click" anti-HER2 antibodies, Fab fragments, or affibodies onto the SPN surface, which allows the functionalised SPNs to specifically target HER2-positive cancer cells. In vivo, our PEGylated SPNs were found to have excellent circulation efficiencies in zebrafish embryos for up to seven days post-injection. SPNs functionalised with affibodies were then shown to be able to target HER2 expressing cancer cells in a zebrafish xenograft model. The covalent PEGylated SPN system described herein shows great potential for cancer theranostics. This article is protected by copyright. All rights reserved

Natural and social interests of the chosen spa region as a destination of tourism

The completion of the evaluation of the influence of natural and social interests in spas on the west of the Czech Republic, the elaboration of situation analysis and the examination of better usage of the area were the principal aims of this bachelor work. The field survey by the help of questionnaires and personal research in the region were parts of this work. These information were worked up and interpreted then. On the basis of the opinion poll new arrangements for improvement of enjoyment in the region were suggested. There were three hypotheses determined that were refutated or confirmed during the time

An annotated list of the species of lice (Insecta: Phthiraptera) described by Mohammad A.-R. Ansari

Naz, Saima, Najer, Tomas, Gustafsson, Daniel R. (2020): An annotated list of the species of lice (Insecta: Phthiraptera) described by Mohammad A.-R. Ansari. Zootaxa 4809 (3): 401-448, DOI: 10.11646/zootaxa.4809.3.

New species of Philopterus Nitzsch, 1818 (Ischnocera: Philopteridae), with notes on Cypseloecus Conci, 1941

We describe and illustrate eight new species of chewing lice in the genus Philopterus Nitzsch, 1818, parasitic on hosts in the bird families Cardinalidae, Chloropseidae, Hirundinidae, Icteridae, Motacillidae, Paridae, and Vangidae from China, Peru, South Africa, Thailand, and the USA. They are: Philopterus coriaceus sp. nov. from Molothrus oryzivorus oryzivorus (Gmelin, 1788); P. hebes sp. nov. from Chloropsis aurifrons inornata Kloss, 1918 and C. cochinchinensis kinneari Hall & Deignan, 1956; P. micropunctatus sp. nov. from Anthus hodgsoni Richmond, 1907; P. afropari sp. nov. from Melaniparus cinerascens cinerascens (Vieillot, 1818); P. pseudhirundo sp. nov. from Pseudhirundo griseopyga Sundevall, 1850; P. sinensis sp. nov. from Hemipus picatus capitalis (Horsfield, 1840); P. stansburyensis sp. nov. from Pheucticus melanocephalus melanocephalus (Swainson, 1827); and P. trepostephanus sp. nov. from Tephrodornis virgatus fretensis Robinson & Kloss, 1920 and T. v. mekongensis Meyer de Schauensee, 1946. Philopterus hebes sp. nov. constitutes the first record of the genus Philopterus from the Chloropseidae. We also provide some notes on the morphology and status of Cypseloecus Conci, 1941

The ischnoceran chewing lice (Phthiraptera: Ischnocera) of bulbuls (Aves: Passeriformes: Pycnonotidae), with descriptions of 18 new species

The ischnoceran chewing lice known from bulbuls are discussed and revised, and 18 new species are described. These are: Brueelia celer sp. nov. from Pycnonotus cafer bengalensis Blyth, 1845 and Pycnonotus cafer primrosei Deignan, 1949; Brueelia colindalei sp. nov. from Hemixos castanonotus canipennis Seebohm, 1890; Brueelia doisuthepensis sp. nov. from Alophoixus ochraceus ochraceus (Moore, 1858); Brueelia galeata sp. nov. from Alophoixus pallidus henrici (Oustalet, 1896); Brueelia hermetica sp. nov. from Pycnonotus barbatus layardi Gurney, 1879; Brueelia leiae sp. nov. from Alophoixus flaveolus burmanicus (Oates, 1899); Brueelia robertrankini sp. nov. from Pycnonotus jocosus jocosus (Linnaeus, 1758) and Pycnonotus jocosus pattani Deignan, 1948; Brueelia yunnanensis sp. nov. from Ixos mcclellandii similis (Rothschild, 1921); Guimaraesiella brunneomarginata sp. nov. from Pycnonotus goiaver samarensis Rand & Rabor, 1960 and Pycnonotus goiaver personatus Hume, 1873; Guimaraesiella caligogularis sp. nov. from Pycnonotus plumosus plumosus Blyth, 1845 and Alophoixus bres tephrogenys (Jardine & Selby, 1833); Guimaraesiella cinnamomea sp. nov. from Iole propinqua propinqua (Oustalet, 1903) and Iole viridescens cinnamomeoventris Baker, 1917; Guimaraesiella ixi sp. nov. from Ixos mcclellandii peracensis (Hartert & Butler, 1898); Guimaraesiella lorica sp. nov. from Hypsipetes leucocephalus nigerrimus Gould, 1863; Guimaraesiella mayoensis sp. nov. from Hypsipetes everetti everetti (Tweeddale, 1877); Guimaraesiella phlaoalopha sp. nov. from Alophoixus pallidus henrici (Oustalet, 1896); Philopteroides holosternus sp. nov. from Pycnonotus goiavier goiavier (Scopoli, 1786); Philopteroides longiclypeatus sp. nov. from Hypsipetes everretti samarensis Rand & Rabor, 1959; Philopteroides haerixos sp. nov. from Ixos mcclellandii holtii (Swinhoe, 1861) and Alophoixus pallidus henrici (Oustalet, 1896). The following new host records are provided: Hemixos castanonotus canipennis Seebohm, 1890, for Guimaraesiella flavala (Najer & Sychra in Najer et al., 2012); Pycnonotus blanfordi conradi (Finsch in Finsch & Conrad, 1873) for Philopteroides cucphuongensis Mey, 2004. Philopterus cucphuongensis is tentatively redescribed and illustrated based on specimens from a non-type host species. The species descriptions of the following species are amended slightly, based on re-examinations of type specimens: Brueelia alophoixi Sychra in Sychra et al., 2009; Guimaraesiella cucphuongensis (Najer & Sychra in Najer et al., 2012); Guimaraesiella flavala (Najer & Sychra in Najer et al., 2012). We propose to move Philopterus hiyodori Uchida, 1949, to the genus Craspedorrhynchus Kéler, 1938. The species Sturnidoecus acutifrons (Uchida, 1949) and Penenirmus guldum (Ansari, 1955) are considered species inquirenda. An updated checklist of ischnoceran lice known from bulbuls is provided, as well as a key to all ischnoceran species known from bulbuls