Realization of two Fourier-limited solid-state single-photon sources

We demonstrate two solid-state sources of indistinguishable single photons. High resolution laser spectroscopy and optical microscopy were combined at T = 1.4 K to identify individual molecules in two independent microscopes. The Stark effect was exploited to shift the transition frequency of a given molecule and thus obtain single photon sources with perfect spectral overlap. Our experimental arrangement sets the ground for the realization of various quantum interference and information processing experiments.Comment: 6 page

Molecules as Sources for Indistinguishable Single Photons

We report on the triggered generation of indistinguishable photons by solid-state single-photon sources in two separate cryogenic laser scanning microscopes. Organic fluorescent molecules were used as emitters and investigated by means of high resolution laser spectroscopy. Continuous-wave photon correlation measurements on individual molecules proved the isolation of single quantum systems. By using frequency selective pulsed excitation of the molecule and efficient spectral filtering of its emission, we produced triggered Fourier-limited single photons. In a further step, local electric fields were applied to match the emission wavelengths of two different molecules via Stark effect. Identical single photons are indispensible for the realization of various quantum information processing schemes proposed. The solid-state approach presented here prepares the way towards the integration of multiple bright sources of single photons on a single chip.Comment: Accepted for publication in J. Mod. Opt. This is the original submitted versio

Quantum Interference of Tunably Indistinguishable Photons from Remote Organic Molecules

We demonstrate two-photon interference using two remote single molecules as bright solid-state sources of indistinguishable photons. By varying the transition frequency and spectral width of one molecule, we tune and explore the effect of photon distinguishability. We discuss future improvements on the brightness of single-photon beams, their integration by large numbers on chips, and the extension of our experimental scheme to coupling and entanglement of distant molecules

Teknologiakasvatuksen ja STEAM-toiminnan erot ja yhtäläisyydet

Tiivistelmä. Teknologia on olennainen osa nyky-yhteiskuntaa ja yhteiskunta kehittyy koko ajan yhä teknologisempaan suuntaan. Teknologian kehityksen takia tulevaisuudessa tullaan tarvitsemaan uusia innovaatioita, jotta voidaan säilyttää kestävä kehitys ja ratkaista kestävyysvaje. Tämän takia tulevaisuudessa tullaan tarvitsemaan enemmän teknologian, tekniikan, matemaattisten sekä luonnontieteellisten alojen osaajia. Teknologiakasvatus ja STEAM-toiminta pyrkivät vastaamaan tulevaisuuden osaajatarpeeseen innostamalla lapsia jo pienestä pitäen teknologian, tekniikan, matematiikan ja luonnontieteiden pariin. Teknologiakasvatuksella ja STEAM-toiminnalla oppilaille pyritään samalla opettamaan tulevaisuuden taitoja, kuten ongelmanratkaisun, luovan- ja kriittisen ajattelun, sekä ryhmätyöskentelytaitoja. Tutkielman tavoitteena on perehtyä teknologiakasvatukseen sekä STEAM-toimintaan ja tarkastella näiden kahden eroja ja yhtäläisyyksiä niiden määritelmien, tavoitteiden ja opetusmenetelmien kautta. Tutkimuksen teoreettinen viitekehys koostuu teknologiakasvatuksen, STEM:in ja STEAM:in määritelmistä sekä näiden yhtäläisyyksistä ja eroista määritelmien ja tavoitteiden tasolla. Tutkimuksessani pääpaino sijoittuu teknologiakasvatukseen ja STEAM:iin, mutta käsittelen myös STEM:iä sekä sen määritelmää, sillä se on olennainen osa STEAM:ia ja sen kehitystä. Olen toteuttanut tutkimukseni kirjallisuuskatsauksena ja tarkastelen aihettani aikaisempien tutkimusten perusteella. Teknologiakasvatus ja STEAM ovat ajankohtaisia aiheita, sillä teknologiakasvatus on ollut osa suomalaista perusopetusta jo useamman vuoden ajan, kun taas STEAM on suomalaisessa koulumaailmassa vielä suhteellisen tuore lähestymistapa opetukseen. Koska teknologiakasvatus on kentällä jo tuttu, olisi hyvä tarkastella ja tutkia STEAM:ia tarkemmin, jotta tietoisuutta ja ymmärrystä STEAM:ista saataisiin vietyä myös kentälle. Tutkimuksessa selviää, että teknologiakasvatuksella ja STEAM-toiminnalla on useita yhtymäkohtia keskenään. Molemmilla on myös yhteyksiä konstruktivistiseen oppimiskäsitykseen ja konstruktivistisiin opetusmenetelmiin

The importance of genuine service and human interaction for millennials’ guest experience: the case of hotel reception and front line employees.

Submitted document is an extended abstract

The endocytic pathways of a secretory granule membrane protein in HEK293 cells : PAM and EGF traverse a dynamic multivesicular body network together

Peptidylglycine alpha-amidating monooxygenase (PAM) is highly expressed in neurons and endocrine cells, where it catalyzes one of the final steps in the biosynthesis of bioactive peptides. PAM is also expressed in unicellular organisms such as Chlamydomonas reinhardtii, which do not store peptides in secretory granules. As for other granule membrane proteins, PAM is retrieved from the cell surface and returned to the trans-Golgi network. This pathway involves regulated entry of PAM into multivesicular body intralumenal vesicles (ILVs). The aim of this study was defining the endocytic pathways utilized by PAM in cells that do not store secretory products in granules. Using stably transfected HEK293 cells, endocytic trafficking of PAM was compared to that of the mannose 6-phosphate (MPR) and EGF (EGFR) receptors, established markers for the endosome to trans-Golgi network and degradative pathways, respectively. As in neuroendocrine cells, PAM internalized by HEK293 cells accumulated in the trans-Golgi network. Based on surface biotinylation, >70% of the PAM on the cell surface was recovered intact after a 4 h chase and soluble, bifunctional PAM was produced. Endosomes containing PAM generally contained both EGFR and MPR and ultrastructural analysis confirmed that all three cargos accumulated in ILVs. PAM containing multivesicular bodies made frequent dynamic tubular contacts with younger and older multivesicular bodies. Frequent dynamic contacts were observed between lysosomes and PAM containing early endosomes and multivesicular bodies. The ancient ability of PAM to localize to ciliary membranes, which release bioactive ectosomes, may be related to its ability to accumulate in ILVs and exosomes. (C) 2017 Elsevier GmbH. All rights reserved.Peer reviewe

Influence of non-universal effects on dynamical scaling in driven polymer translocation

We study the dynamics of driven polymer translocation using both molecular dynamics (MD) simulations and a theoretical model based on the non-equilibrium tension propagation on the cis side subchain. We present theoretical and numerical evidence that the non-universal behavior observed in experiments and simulations are due to finite chain length effects that persist well beyond the relevant experimental and simulation regimes. In particular, we consider the influence of the pore-polymer interactions and show that they give a major contribution to the non-universal effects. In addition, we present comparisons between the theory and MD simulations for several quantities, showing extremely good agreement in the relevant parameter regimes. Finally, we discuss the potential limitations of the present theories.Peer reviewe

What dictates the accumulation of desmosterol in the developing brain?

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Comparison of six tag types in sea-trout tagging experiments in the Baltic Sea

In the international Baltic Sea trout tagging experiment 27 753 hatchery reared sea trout smolts were tagged in Denmark, Finland, Poland and Sweden in 1979 and 1980. The fish were tagged with the original Carlin tag, two modified Carlin tag types (Canadian and Finnish polythene), streamer and Floy tags and Polish tags attached with Monel metal wire. The tag returns were affected by the place of release and smolt quality. The best results were obtained in the case of tags attached with double wire or thread -original Carlin, Canadian and Finnish polythene. The poorest results were obtained with streamer tags

Europium-based high-temperature superconductors studied by x-ray diffraction and 151Eu Mössbauer spectroscopy

Isotropic powders and magnetically aligned crystallites of EuBa2Cu3O7−δ (1:2:3) and europium-doped Bi2Sr2CaCu2O8 (2:2:1:2) were studied by means of x-ray diffraction and Eu151 Mössbauer spectroscopy. The degree of crystallite orientation of the samples and the values of the lattice constants were determined by x-ray diffraction. The Mössbauer spectra were analyzed considering the full hyperfine Hamiltonian of the nuclear states of the 21.5-keV γ transition. The Mössbauer hyperfine parameters obtained from the superconducting and semiconducting phases are presented. A small change is seen in the Eu151 isomer shift when the oxygen deficiency δ of the 1:2:3 compound is varied. The shift can be explained by a decrease in the s-electron density due to lattice expansion. The changes in the oxidation state of the copper atoms with varying δ were determined from the Mössbauer data: The Cu(2) atoms retain their oxidation state, whereas the Cu(1) atoms adjust their valence according to the value of δ. In the 2:2:1:2 samples, the Eu concentration clearly affected the value of the electric-field gradient at the Eu nucleus. Using a standard procedure, magnetically aligned 2:2:1:2 samples were prepared. The preferred direction of the crystal c axis changed from parallel to perpendicular alignment with the external magnetic field, when the Eu concentration exceeded 20% of the Ca atoms.Peer reviewe