TY - JOUR A1 - Rau, Markus A1 - Heindel, Tobias A1 - Unsleber, Sebastian A1 - Braun, Tristan A1 - Fischer, Julian A1 - Frick, Stefan A1 - Nauerth, Sebastian A1 - Schneider, Christian A1 - Vest, Gwenaelle A1 - Reitzenstein, Stephan A1 - Kamp, Martin A1 - Forchel, Alfred A1 - Höfling, Sven A1 - Weinfurter, Harald T1 - Free space quantum key distribution over 500 meters using electrically driven quantum dot single-photon sources-a proof of principle experiment JF - New Journal of Physics N2 - Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5-17 kHz with error ratios of 6-9% and g((2))(0)-values of 0.39-0.76. KW - QKD KW - electrically driven KW - free space KW - quantum dots KW - quantum key distribution Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-116760 VL - 16 IS - 043003 ER - TY - JOUR A1 - Kim, Seonghoon A1 - Zhang, Bo A1 - Wang, Zhaorong A1 - Fischer, Julian A1 - Brodbeck, Sebastian A1 - Kamp, Martin A1 - Schneider, Christian A1 - Höfling, Sven A1 - Deng, Hui T1 - Coherent Polariton Laser JF - Physical Review X N2 - The semiconductor polariton laser promises a new source of coherent light, which, compared to conventional semiconductor photon lasers, has input-energy threshold orders of magnitude lower. However, intensity stability, a defining feature of a coherent state, has remained poor. Intensity noise many times the shot noise of a coherent state has persisted, attributed to multiple mechanisms that are difficult to separate in conventional polariton systems. The large intensity noise, in turn, limits the phase coherence. Thus, the capability of the polariton laser as a source of coherence light is limited. Here, we demonstrate a polariton laser with shot-noise-limited intensity stability, as expected from a fully coherent state. This stability is achieved by using an optical cavity with high mode selectivity to enforce single-mode lasing, suppress condensate depletion, and establish gain saturation. Moreover, the absence of spurious intensity fluctuations enables the measurement of a transition from exponential to Gaussian decay of the phase coherence of the polariton laser. It suggests large self-interaction energies in the polariton condensate, exceeding the laser bandwidth. Such strong interactions are unique to matter-wave lasers and important for nonlinear polariton devices. The results will guide future development of polariton lasers and nonlinear polariton devices. KW - polariton laser KW - condensed matter physics KW - photonics KW - quantum physics KW - coherent light Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166597 VL - 6 IS - 011026 ER - TY - JOUR A1 - Kempert, Sebastian A1 - Götz, Regina A1 - Blatter, Kristine A1 - Tibken, Catharina A1 - Artelt, Cordula A1 - Schneider, Wolfgang A1 - Stanat, Petra T1 - Training Early Literacy Related Skills: To Which Degree Does a Musical Training Contribute to Phonological Awareness Development? JF - Frontiers in Psychology N2 - Well-developed phonological awareness skills are a core prerequisite for early literacy development. Although effective phonological awareness training programs exist, children at risk often do not reach similar levels of phonological awareness after the intervention as children with normally developed skills. Based on theoretical considerations and first promising results the present study explores effects of an early musical training in combination with a conventional phonological training in children with weak phonological awareness skills. Using a quasi-experimental pretest-posttest control group design and measurements across a period of 2 years, we tested the effects of two interventions: a consecutive combination of a musical and a phonological training and a phonological training alone. The design made it possible to disentangle effects of the musical training alone as well the effects of its combination with the phonological training. The outcome measures of these groups were compared with the control group with multivariate analyses, controlling for a number of background variables. The sample included N = 424 German-speaking children aged 4–5 years at the beginning of the study. We found a positive relationship between musical abilities and phonological awareness. Yet, whereas the well-established phonological training produced the expected effects, adding a musical training did not contribute significantly to phonological awareness development. Training effects were partly dependent on the initial level of phonological awareness. Possible reasons for the lack of training effects in the musical part of the combination condition as well as practical implications for early literacy education are discussed. KW - phonological awareness KW - musical training KW - phonological training KW - preschool children KW - early literacy Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-165272 VL - 7 IS - 1803 ER - TY - JOUR A1 - Lundt, Nils A1 - Klembt, Sebastian A1 - Cherotchenko, Evgeniia A1 - Betzold, Simon A1 - Iff, Oliver A1 - Nalitov, Anton V. A1 - Klaas, Martin A1 - Dietrich, Christof P. A1 - Kavokin, Alexey V. A1 - Höfling, Sven A1 - Schneider, Christian T1 - Room-temperature Tamm-plasmon exciton-polaritons with a WSe\(_{2}\) monolayer JF - Nature Communications N2 - Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light–matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe\(_{2}\), hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy–momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons. KW - optics and photonics KW - two-dimensional materials KW - electronic properties and materials Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169470 VL - 7 ER - TY - JOUR A1 - Doerck, Sebastian A1 - Goebel, Kerstin A1 - Weise, Gesa A1 - Schneider-Hohendorf, Tilman A1 - Reinhardt, Michael A1 - Hauff, Peter A1 - Schwab, Nicholas A1 - Linker, Ralf A1 - Maeurer, Mathias A1 - Meuth, Sven G. A1 - Wiendl, Heinz T1 - Temporal Pattern of ICAM-I Mediated Regulatory T Cell Recruitment to Sites of Inflammation in Adoptive Transfer Model of Multiple Sclerosis N2 - Migration of immune cells to the target organ plays a key role in autoimmune disorders like multiple sclerosis (MS). However, the exact underlying mechanisms of this active process during autoimmune lesion pathogenesis remain elusive. To test if pro-inflammatory and regulatory T cells migrate via a similar molecular mechanism, we analyzed the expression of different adhesion molecules, as well as the composition of infiltrating T cells in an in vivo model of MS, adoptive transfer experimental autoimmune encephalomyelitis in rats. We found that the upregulation of ICAM-I and VCAM-I parallels the development of clinical disease onset, but persists on elevated levels also in the phase of clinical remission. However, the composition of infiltrating T cells found in the developing versus resolving lesion phase changed over time, containing increased numbers of regulatory T cells (FoxP3) only in the phase of clinical remission. In order to test the relevance of the expression of cell adhesion molecules, animals were treated with purified antibodies to ICAM-I and VCAM-I either in the phase of active disease or in early remission. Treatment with a blocking ICAM-I antibody in the phase of disease progression led to a milder disease course. However, administration during early clinical remission aggravates clinical symptoms. Treatment with anti-VCAM-I at different timepoints had no significant effect on the disease course. In summary, our results indicate that adhesion molecules are not only important for capture and migration of pro-inflammatory T cells into the central nervous system, but also permit access of anti-inflammatory cells, such as regulatory T cells. Therefore it is likely to assume that intervention at the blood brain barrier is time dependent and could result in different therapeutic outcomes depending on the phase of CNS lesion development. KW - Multiple Sklerose Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68565 ER - TY - JOUR A1 - Amthor, Matthias A1 - Weißenseel, Sebastian A1 - Fischer, Julian A1 - Kamp, Martin A1 - Schneider, Christian A1 - Höfling, Sven T1 - Electro-optical switching between polariton and cavity lasing in an InGaAs quantum well microcavity N2 - We report on the condensation of microcavity exciton polaritons under optical excitation in a microcavity with four embedded InGaAs quantum wells. The polariton laser is characterized by a distinct nonlinearity in the input-output-characteristics, which is accompanied by a drop of the emission linewidth indicating temporal coherence and a characteristic persisting emission blueshift with increased particle density. The temporal coherence of the device at threshold is underlined by a characteristic drop of the second order coherence function to a value close to 1. Furthermore an external electric field is used to switch between polariton regime, polariton condensate and photon lasing. KW - Quantum-well, -wire and -dot devices KW - Scattering KW - stimulated KW - Resonators KW - Microcavity devices Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-111130 ER - TY - JOUR A1 - Maier, Sebastian A1 - Gold, Peter A1 - Forchel, Alfred A1 - Gregersen, Niels A1 - Mork, Jesper A1 - Höfling, Sven A1 - Schneider, Christian A1 - Kamp, Martin T1 - Bright single photon source based on self-aligned quantum dot-cavity systems JF - Optics Express N2 - We report on a quasi-planar quantum-dot-based single-photon source that shows an unprecedented high extraction efficiency of 42% without complex photonic resonator geometries or post-growth nanofabrication. This very high efficiency originates from the coupling of the photons emitted by a quantum dot to a Gaussian shaped nanohill defect that naturally arises during epitaxial growth in a self-aligned manner. We investigate the morphology of these defects and characterize the photonic operation mechanism. Our results show that these naturally arising coupled quantum dot-defects provide a new avenue for efficient (up to 42% demonstrated) and pure (g(2)(0) value of 0.023) single-photon emission. KW - photon statistics KW - quantum communications KW - resonators KW - quantum-well -wire and -dot devices Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119801 SN - 1094-4087 VL - 22 IS - 7 ER - TY - JOUR A1 - Yu, Leo A1 - Natarajan, Chandra M. A1 - Horikiri, Tomoyuki A1 - Langrock, Carsten A1 - Pelc, Jason S. A1 - Tanner, Michael G. A1 - Abe, Eisuke A1 - Maier, Sebastian A1 - Schneider, Christian A1 - Höfling, Sven A1 - Kamp, Martin A1 - Hadfield, Robert H. A1 - Fejer, Martin M. A1 - Yamamoto, Yoshihisa T1 - Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits JF - Nature Communications N2 - Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances. KW - atom KW - 1550 nm KW - up-conversion KW - heralded entanglement KW - emission KW - interface KW - generation KW - communication KW - downconversion Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138677 VL - 6 ER - TY - JOUR A1 - Manchia, Mirko A1 - Adli, Mazda A1 - Akula, Nirmala A1 - Arda, Raffaella A1 - Aubry, Jean-Michel A1 - Backlund, Lena A1 - Banzato, Claudio E. M. A1 - Baune, Bernhard T. A1 - Bellivier, Frank A1 - Bengesser, Susanne A1 - Biernacka, Joanna M. A1 - Brichant-Petitjean, Clara A1 - Bui, Elise A1 - Calkin, Cynthia V. A1 - Cheng, Andrew Tai Ann A1 - Chillotti, Caterina A1 - Cichon, Sven A1 - Clark, Scott A1 - Czerski, Piotr M. A1 - Dantas, Clarissa A1 - Del Zompo, Maria A1 - DePaulo, J. Raymond A1 - Detera-Wadleigh, Sevilla D. A1 - Etain, Bruno A1 - Falkai, Peter A1 - Frisén, Louise A1 - Frye, Mark A. A1 - Fullerton, Jan A1 - Gard, Sébastien A1 - Garnham, Julie A1 - Goes, Fernando S. A1 - Grof, Paul A1 - Gruber, Oliver A1 - Hashimoto, Ryota A1 - Hauser, Joanna A1 - Heilbronner, Urs A1 - Hoban, Rebecca A1 - Hou, Liping A1 - Jamain, Stéphane A1 - Kahn, Jean-Pierre A1 - Kassem, Layla A1 - Kato, Tadafumi A1 - Kelsoe, John R. A1 - Kittel-Schneider, Sarah A1 - Kliwicki, Sebastian A1 - Kuo, Po-Hsiu A1 - Kusumi, Ichiro A1 - Laje, Gonzalo A1 - Lavebratt, Catharina A1 - Leboyer, Marion A1 - Leckband, Susan G. A1 - López Jaramillo, Carlos A. A1 - Maj, Mario A1 - Malafosse, Alain A1 - Martinsson, Lina A1 - Masui, Takuya A1 - Mitchell, Philip B. A1 - Mondimore, Frank A1 - Monteleone, Palmiero A1 - Nallet, Audrey A1 - Neuner, Maria A1 - Novák, Tomás A1 - O'Donovan, Claire A1 - Ösby, Urban A1 - Ozaki, Norio A1 - Perlis, Roy H. A1 - Pfennig, Andrea A1 - Potash, James B. A1 - Reich-Erkelenz, Daniela A1 - Reif, Andreas A1 - Reininghaus, Eva A1 - Richardson, Sara A1 - Rouleau, Guy A. A1 - Rybakowski, Janusz K. A1 - Schalling, Martin A1 - Schofield, Peter R. A1 - Schubert, Oliver K. A1 - Schweizer, Barbara A1 - Seemüller, Florian A1 - Grigoroiu-Serbanescu, Maria A1 - Severino, Giovanni A1 - Seymour, Lisa R. A1 - Slaney, Claire A1 - Smoller, Jordan W. A1 - Squassina, Alessio A1 - Stamm, Thomas A1 - Steele, Jo A1 - Stopkova, Pavla A1 - Tighe, Sarah K. A1 - Tortorella, Alfonso A1 - Turecki, Gustavo A1 - Wray, Naomi R. A1 - Wright, Adam A1 - Zandi, Peter P. A1 - Zilles, David A1 - Bauer, Michael A1 - Rietschel, Marcella A1 - McMahon, Francis J. A1 - Schulze, Thomas G. A1 - Alda, Martin T1 - Assessment of Response to Lithium Maintenance Treatment in Bipolar Disorder: A Consortium on Lithium Genetics (ConLiGen) Report JF - PLoS ONE N2 - Objective: The assessment of response to lithium maintenance treatment in bipolar disorder (BD) is complicated by variable length of treatment, unpredictable clinical course, and often inconsistent compliance. Prospective and retrospective methods of assessment of lithium response have been proposed in the literature. In this study we report the key phenotypic measures of the "Retrospective Criteria of Long-Term Treatment Response in Research Subjects with Bipolar Disorder" scale currently used in the Consortium on Lithium Genetics (ConLiGen) study. Materials and Methods: Twenty-nine ConLiGen sites took part in a two-stage case-vignette rating procedure to examine inter-rater agreement [Kappa (\(\kappa\))] and reliability [intra-class correlation coefficient (ICC)] of lithium response. Annotated first-round vignettes and rating guidelines were circulated to expert research clinicians for training purposes between the two stages. Further, we analyzed the distributional properties of the treatment response scores available for 1,308 patients using mixture modeling. Results: Substantial and moderate agreement was shown across sites in the first and second sets of vignettes (\(\kappa\) = 0.66 and \(\kappa\) = 0.54, respectively), without significant improvement from training. However, definition of response using the A score as a quantitative trait and selecting cases with B criteria of 4 or less showed an improvement between the two stages (\(ICC_1 = 0.71\) and \(ICC_2 = 0.75\), respectively). Mixture modeling of score distribution indicated three subpopulations (full responders, partial responders, non responders). Conclusions: We identified two definitions of lithium response, one dichotomous and the other continuous, with moderate to substantial inter-rater agreement and reliability. Accurate phenotypic measurement of lithium response is crucial for the ongoing ConLiGen pharmacogenomic study. KW - age KW - observer agreement KW - prophylactic lithium KW - mapping susceptibility genes KW - mood disorders KW - onset KW - association KW - reliability KW - morality KW - illness Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130938 VL - 8 IS - 6 ER - TY - THES A1 - Schneider, Sebastian T1 - Karpale Bandverletzungen - Vergleich der direkten MR-Arthrographie mit der diagnostischen Arthroskopie unter Berücksichtigung von Partialdefekten des skapholunären Bandes, des lunatotriquetralen Bandes sowie des TFCC T1 - Direct MR Arthrography of the wrist – Value in Detecting Complete and Partial Defects of intrinsic Ligaments and the TFCC in Comparison with Arthroscopy N2 - Evaluation von Defekten des triangulären fibrokartilaginären Komplexes (TFCC) und der intrinsischen Bänder des Handgelenkes mit der direkten MR-Arthrographie im Vergleich zur diagnostischen Arthroskopie unter besonderer Berücksichtigung von Partialdefekten. Material und Methoden: 75 direkte MR-Arthrographien des Handgelenkes (intraartikuläre Injektion eines Gemisches aus Gadoliniumchelaten und Iotrolan) wurden von zwei erfahrenen Radiologen im Konsens ausgewertet. Es wurden T1-gewichtete Spin-Echo(SE)-Sequenzen in frontaler und sagittaler sowie Fast low angle shot (FLASH) 3D-Sequenzen in frontaler Schichtung akquiriert. Läsionen des skapholunären Bandes wurden entsprechend den Leitlinien der Deutschen Gesellschaft für Handchirurgie (DGH), Läsionen des lunatotriquetralen Bandes nach Hempfling, Läsionen des TFCC nach Palmer eingeteilt. Anschließend wurden die Befunde mit der Arthroskopie als Referenzstandard korreliert. Ergebnisse: Für die Verletzungen der intrinsischen Bänder und des TFCC waren die Sensitivitäten und Spezifitäten für Komplettrupturen 96% und 99,6% (T1-SE) bzw. 92% und 100% (FLASH 3D), für Partialdefekte 68,1% und 93,3% (T1-SE) bzw. 63% und 96,1% (FLASH 3D). Die T1-SE-Sequenz eignete sich für die Einschätzung skapholunärer Banddefekte besser als die FLASH 3D-Sequenz (p < 0,05). Für Partialdefekte das skapholunären Bandes wurde mit der T1-SE-Sequenz eine Sensitivität von 83,3%, mit der FLASH 3D-Sequenz von 64,7% erreicht. Schlussfolgerung: Die direkte MR-Arthrographie ist bei der Einschätzung von Komplettrupturen der intrinsischen Bänder und des TFCC der diagnostischen Arthroskopie gleichwertig. Mit der T1-SE-Sequenz sind Partialdefekte des skapholunären Bandes im Vergleich zur Arthroskopie mit ausreichender Sicherheit erkennbar. Die T1-SE-Sequenz war hierfür der FLASH 3D-Sequenz überlegen (p < 0,05) und sollte bei der Einschätzung skapholunärer Partialdefekte bevorzugt werden. Die Einschätzung des lunatotriquetralen Bandes gelingt nicht zuverlässig. N2 - To assess the value of two-compartment magnetic resonance (MR) wrist arthrography in comparison with arthroscopy for the evaluation of defects of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments in patients with refractory wrist pain. The direct MR arthrographics were evaluated following arthroscopy classification with consideration of complete and partial defects. The distinction between these types of lesions has clinical implications for treatment procedures such as cast immobilization, arthroscopic debridement, surgical repair or partial intercarpal arthrodesis. Materials and Methods: Seventy-five patients (25 female, 50 males, mean age 38.3 years) who suffered from refractory wrist pain without radiography evidence of carpal instability underwent two-compartment wrist MR arthrography. Under aseptic conditions a solution of gadopentate dimeglumine and iodinated contrast agent (concentration 2.5mmol/l) was injected into the radiocarpal and midcarpal joints under fluorscopy guidance. Using a scanner of 1.5T field strength and a wrist-coil following sequences were acquired: coronary and sagittal T1-weighted spin-echo (SE) sequences (TR 500ms, TE 25ms, matrix 512*512, 3mm) and coronary fast low angle shot (FLASH) 3D sequences (TR 24ms, TE 11ms, matrix 256*256, 1.5mm, flip angle 50 degrees). All patients underwent subsequent arthroscopy of the wrist. The direct MR arthrographies were evaluated retrospectively by two observers experienced in the diagnosis of wrist pathology. They were not aware of the clinical, arthrographic and arthroscopic findings. Pathology of the scapholunate ligament was classified according to the guidelines of the German Society of Hand Surgery (DGH), lesions of the lunotriquetral ligament according to Hempfling and lesions of the TFCC according to Palmer. Results: Twenty-five complete and 47 partial defects were detected arthroscopically (TFCC: 21/20, scapholunate ligament: 3/18, lunotriquetral ligament: 1/9). The TFCC showed a higher prevalence for degenerative lesions (11 type 2C-lesions and 20 type 2A/B-lesions) than for traumatic lesions (5 type 1A-lesions, 5 type 1D-lesions). For direct MR arthrography , the obtained sensitivities and specificities in assessing complete defects were 96% and 99.6% (T1-weigthed SE) and 92% and 100% (FLASH 3D), respectively. For all partial defects, sensitivities and specificities were 68.1% and 93.3% (T1-weigthed SE) and 63% and 96.1% (FLASH 3D), respectively. For depicting partial defects of the scapholunate ligament the T1-weigthed SE sequence (83.3/95.5%) was superior to the FLASH 3D sequence (64.7/96.6%), p < 00.5. For the evaluation of the TFCC (T1-weigthed SE: 65/94.4%, FLASH 3D: 70/94.6%) and the lunotriquetral ligament (T1-weigthed SE: 44/89.4%, FLASH 3D: 44/96.7%), direct MR arthrography showed an insufficient correlation with arthroscopy. Conclusion: Direct MR arthrography proved to be of equal value compared with diagnostic arthroscopy in detecting complete defects of the intrinsic ligaments and the TFCC. The method has the potential of replacing diagnostic arthroscopy for the evaluation of the intrinsic ligaments and the TFCC. The T1-weigthed SE sequence appeared to be superior to the FLASH 3D sequence in evaluating partial defects of the scapholunate ligament. Direct MR arthrography did not reliably detect partial defects of the TFCC and the lunotriquetral ligament. KW - MRT KW - Arthroskopie KW - MR-Arthrographie KW - Hand KW - Bänder KW - TFCC KW - MRI KW - arthroscopy KW - MR arthrography KW - wrist KW - ligaments KW - TFCC Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-7970 ER -