Quantum-dot single-photon sources for entanglement enhanced interferometry

The authors acknowledge financial support from the Center for Integrated Quantum Science and Technology (IQST).Multiphoton entangled states such as “N00N states” have attracted a lot of attention because of their possible application in high-precision, quantum enhanced phase determination. So far, N00N states have been generated in spontaneous parametric down-conversion processes and by mixing quantum and classical light on a beam splitter. Here, in contrast, we demonstrate superresolving phase measurements based on two-photon N00N states generated by quantum dot single-photon sources making use of the Hong-Ou-Mandel effect on a beam splitter. By means of pulsed resonance fluorescence of a charged exciton state, we achieve, in postselection, a quantum enhanced improvement of the precision in phase uncertainty, higher than prescribed by the standard quantum limit. An analytical description of the measurement scheme is provided, reflecting requirements, capability, and restraints of single-photon emitters in optical quantum metrology. Our results point toward the realization of a real-world quantum sensor in the near future.PostprintPostprintPeer reviewe

Quantum-dot single-photon sources for entanglement enhanced interferometry

The authors acknowledge financial support from the Center for Integrated Quantum Science and Technology (IQST).Multiphoton entangled states such as “N00N states” have attracted a lot of attention because of their possible application in high-precision, quantum enhanced phase determination. So far, N00N states have been generated in spontaneous parametric down-conversion processes and by mixing quantum and classical light on a beam splitter. Here, in contrast, we demonstrate superresolving phase measurements based on two-photon N00N states generated by quantum dot single-photon sources making use of the Hong-Ou-Mandel effect on a beam splitter. By means of pulsed resonance fluorescence of a charged exciton state, we achieve, in postselection, a quantum enhanced improvement of the precision in phase uncertainty, higher than prescribed by the standard quantum limit. An analytical description of the measurement scheme is provided, reflecting requirements, capability, and restraints of single-photon emitters in optical quantum metrology. Our results point toward the realization of a real-world quantum sensor in the near future.PostprintPostprintPeer reviewe

Room temperature organic exciton-polariton condensate in a lattice

Funding: The Würzburg group acknowledges financial support from the state of Bavaria. We also thank the Würzburg–Dresden Cluster of Excellence ct.qmat for financial support.Interacting Bosons in artificial lattices have emerged as a modern platform to explore collective manybody phenomena and exotic phases of matter as well as to enable advanced on-chip simulators. On chip, exciton–polaritons emerged as a promising system to implement and study bosonic non-linear systems in lattices, demanding cryogenic temperatures. We discuss an experiment conducted on a polaritonic lattice at ambient conditions: We utilize fluorescent proteins providing ultra-stable Frenkel excitons. Their soft nature allows for mechanically shaping them in the photonic lattice. We demonstrate controlled loading of the coherent condensate in distinct orbital lattice modes of different symmetries. Finally, we explore the self-localization of the condensate in a gap-state, driven by the interplay of effective interaction and negative effective mass in our lattice. We believe that this work establishes organic polaritons as a serious contender to the well-established GaAs platform for a wide range of applications relying on coherent Bosons in lattices.Publisher PDFPeer reviewe

Two-component system vicrk regulates functions associated with establishment of streptococcus sanguinis in biofilms

Streptococcus sanguinis is a commensal pioneer colonizer of teeth and an opportunistic pathogen of infectious endocarditis. The establishment of S. sanguinis in host sites likely requires dynamic fitting of the cell wall in response to local stimuli. In this study, we investigated the two-component system (TCS) VicRK in S. sanguinis (VicRKSs), which regulates genes of cell wall biogenesis, biofilm formation, and virulence in opportunistic pathogens. A vicK knockout mutant obtained from strain SK36 (SKvic) showed slight reductions in aerobic growth and resistance to oxidative stress but an impaired ability to form biofilms, a phenotype restored in the complemented mutant. The biofilm-defective phenotype was associated with reduced amounts of extracellular DNA during aerobic growth, with reduced production of H2O2, a metabolic product associated with DNA release, and with inhibitory capacity of S. sanguinis competitor species. No changes in autolysis or cell surface hydrophobicity were detected in SKvic. Reverse transcription-quantitative PCR (RT-qPCR), electrophoretic mobility shift assays (EMSA), and promoter sequence analyses revealed that VicR directly regulates genes encoding murein hydrolases (SSA_0094, cwdP, and gbpB) and spxB, which encodes pyruvate oxidase for H2O2 production. Genes previously associated with spxB expression (spxR, ccpA, ackA, and tpK) were not transcriptionally affected in SKvic. RT-qPCR analyses of S. sanguinis biofilm cells further showed upregulation of VicRK targets (spxB, gbpB, and SSA_0094) and other genes for biofilm formation (gtfP and comE) compared to expression in planktonic cells. This study provides evidence that VicRKSs regulates functions crucial for S. sanguinis establishment in biofilms and identifies novel VicRK targets potentially involved in hydrolytic activities of the cell wall required for these functions.Streptococcus sanguinis is a commensal pioneer colonizer of teeth and an opportunistic pathogen of infectious endocarditis. The establishment of S. sanguinis in host sites likely requires dynamic fitting of the cell wall in response to local stimuli. In t821249414951FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIOR2009/54182-7; 2008/58333-7; 2009/50547-0sem informaçã

Integrin Activation Promotes Axon Growth on Inhibitory Chondroitin Sulfate Proteoglycans by Enhancing Integrin Signaling

We report on the enhancement of the spontaneous emission in the visible red spectral range from site-controlled InP/GaInP quantum dots by resonant coupling to Tammplasmon modes confined beneath gold disks in a hybrid metal/semiconductor structure. The enhancement of the emission intensity is confirmed by spatially resolved microphotoluminescence area scans and temperature dependent measurements. Single photon emission from our coupled system is verified via second order autocorrelation measurements. We observe bright single quantum dot emission of up to ~173000 detected photons per second at a repetition rate of the excitation source of 82 MHz, and calculate an extraction efficiency of our device as high as 7%

Collective state transitions of exciton-polaritons loaded into a periodic potential

O.A.E. acknowledges financial support by the Deutsche Forschungsgemeinschaft (DFG project EG344/2-1) and by the EU project (FP7, PIRSES-GA-2013-612600) LIMACONA. I.G.S. acknowledges support from the Academy of Finland through its Centre of Excellence Programs (Projects No. 250280 and No. 251748); Government of Russian Federation (project MK-5903.2016.2); and Dynasty Foundation. E.E., T.G., I.G.S., and E.A.O. acknowledge support by the Australian Research Council.We study the loading of a nonequilibrium, dissipative system of composite bosons - exciton polaritons - into a one dimensional periodic lattice potential. Utilizing momentum resolved photoluminescence spectroscopy, we observe a transition between an incoherent Bose gas and a polariton condensate, which undergoes further transitions between different energy states in the band-gap spectrum of the periodic potential with increasing pumping power. We demonstrate controlled loading into distinct energy bands by modifying the size and shape of the excitation beam. The observed effects are comprehensively described in the framework of a nonequilibrium model of polariton condensation. In particular, we implement a stochastic treatment of quantum and thermal fluctuations in the system and confirm that polariton-phonon scattering is a key energy relaxation mechanism enabling transitions from the highly nonequilibrium polariton condensate in the gap to the ground band condensation for large pump powers.PostprintPostprintPeer reviewe

Proteínas de células totais de leveduras SDS-Page e análise numérica

The application of gel electrophoresis and numerical analysis of yeast soluble proteins analysis to the investigation of 12 oral yeast strains belonging to five species is described. It involves one-dimensional electrophoresis of SDS-solubilized whole-cell proteins using different culture media for the cultivation of the cells, integration densitometries in the areas of the gels and percentages of the proteins extraction. These extracts were prepared from four isolates of Candida albicans, two of C. tropicalis, C. guilliermondii, C. parapsilosis and C. krusei. The extracts from whole-cells proteins using different culture media for the cultivation of the cells were fractionated by slab electrophoresis using a discontinuous buffer system. The corresponding patterns showed at least 36 polypeptides in the range of 14.4-200 kDa. Different isolates of each species were clearly different in each of the five species. The data obtained suggest that different nutritional compositions led to the expression of different proteins derived from alternatives metabolic pathways expressed by the electrophoretic profiles. The construction of a database of protein fingerprints and numerical analysis based on such data, may have some implications in the classification and identification of such species with epidemiological, ecological and taxonomic purposes. A well defined or synthetic culture media seems to be much properly.Neste trabalho são descritas a aplicação de gel de poliacrilamida e a análise numérica no estudo de proteínas solúveis na investigação de 12 amostras de leveduras orais, pertencentes a 5 espécies. Aplicou-se a técnica de eletroforese em gel de poliacrilamida na análise de proteínas de células totais, usando-se diferentes tipos de meios de cultura de células leveduriformes; densitometria de integralização da área dos géis, com a porcentagem de extração das proteínas para cada amostra de meio de cultura; além dos respectivos dendrogramas comparativos. Foram preparados extratos a partir de quatro isolados de C. albicans, dois de C. tropicalis, C. guilliermondi, C. parapsilosis e C. krusei. Os extratos foram fracionados por eletroforese em gel de acrilamida (slab), usando o sistema de tampão descontínuo. Os padrões de bandas protéicas mostraram pelo menos 36 polipeptídios entre 14.4-200 kDa. Dentre os diversos isolados de cada espécie, observaram-se diferenças significativas em cada uma das cinco espécies estudadas. Os dados obtidos sugerem que diferentes composições nutricionais presentes nos meios determinam a ex-pressão de diferentes proteínas, derivadas de mecanismos metabólicos alternativos, expressos nos perfis eletroforéticos. A construção de um banco de dados de proteínas e a análise numérica com base em dados dessa natureza podem ter implicações na diferenciação de espécies, com objetivo epidemiológico, ecológico e taxonômico. Meios nutricionalmente definidos ou sintéticos seriam mais apropriados.50751

Polariton condensation in S- and P-flatbands in a two-dimensional Lieb lattice

S.K. acknowledges the European Commission for the H2020 Marie Sklodowska-Curie Actions (MSCA) fellowship (Topopolis). The Wurzburg group acknowledges the financial support by the state of Bavaria and the Deutsche Forschungsgemeinschaft (DFG) within the project Schn1376-3.1.We study the condensation of exciton-polaritons in a two-dimensional Lieb lattice of micropillars. We show selective polariton condensation into the flatbands formed by S and Px,y orbital modes of the micropillars under non-resonant laser excitation.The real space mode patterns of these condensates are accurately reproduced bythe calculation of related Bloch modes of S- and P-flatbands. Our work emphasizes the potential of exciton-polariton lattices to emulate Hamiltonians of advanced potential landscapes. Furthermore, the obtained results provide a deeper inside into the physics of flatbands known mostly within the tight-binding limit.PostprintPostprintPeer reviewe