Measurement Induced Enhancement of Squeezing in Nondegenerate Two-Photon Jaynes-Cummings Model

International Nuclear Information System (INIS)

Ye Saiyun

2006-01-01

Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement.

Enhancement of two-photon photoluminescence and SERS for low-coverage gold films

DEFF Research Database (Denmark)

Novikov, Sergey M.; Beermann, Jonas; Frydendahl, Christian

2016-01-01

Electromagnetic field enhancement (FE) effects occurring in thin gold films 3-12-nm are investigated with two-photon photoluminescence (TPL) and Raman scanning optical microscopies. The samples are characterized using scanning electron microscopy images and linear optical spectroscopy. TPL images...... exhibit a strong increase in the level of TPL signals for films thicknesses 3-8-nm, near the percolation threshold. For some thicknesses, TPL measurements reveal super-cubic dependences on the incident power. We ascribe this feature to the occurrence of very strongly localized and enhanced electromagnetic...

Quantum entanglement and phase transition in a two-dimensional photon-photon pair model

International Nuclear Information System (INIS)

Zhang Jianjun; Yuan Jianhui; Zhang Junpei; Cheng Ze

2013-01-01

We propose a two-dimensional model consisting of photons and photon pairs. In the model, the mixed gas of photons and photon pairs is formally equivalent to a two-dimensional system of massive bosons with non-vanishing chemical potential, which implies the existence of two possible condensate phases. Using the variational method, we discuss the quantum phase transition of the mixed gas and obtain the critical coupling line analytically. Moreover, we also find that the phase transition of the photon gas can be interpreted as enhanced second harmonic generation. We then discuss the entanglement between photons and photon pairs. Additionally, we also illustrate how the entanglement between photons and photon pairs can be associated with the phase transition of the system.

Photon statistical properties of photon-added two-mode squeezed coherent states

International Nuclear Information System (INIS)

Xu Xue-Fen; Wang Shuai; Tang Bin

2014-01-01

We investigate photon statistical properties of the multiple-photon-added two-mode squeezed coherent states (PA-TMSCS). We find that the photon statistical properties are sensitive to the compound phase involved in the TMSCS. Our numerical analyses show that the photon addition can enhance the cross-correlation and anti-bunching effects of the PA-TMSCS. Compared with that of the TMSCS, the photon number distribution of the PA-TMSCS is modulated by a factor that is a monotonically increasing function of the numbers of adding photons to each mode; further, that the photon addition essentially shifts the photon number distribution. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Polarized two-photon photoselection in EGFP: Theory and experiment.

Science.gov (United States)

Masters, T A; Marsh, R J; Blacker, T S; Armoogum, D A; Larijani, B; Bain, A J

2018-04-07

In this work, we present a complete theoretical description of the excited state order created by two-photon photoselection from an isotropic ground state; this encompasses both the conventionally measured quadrupolar (K = 2) and the "hidden" degree of hexadecapolar (K = 4) transition dipole alignment, their dependence on the two-photon transition tensor and emission transition dipole moment orientation. Linearly and circularly polarized two-photon absorption (TPA) and time-resolved single- and two-photon fluorescence anisotropy measurements are used to determine the structure of the transition tensor in the deprotonated form of enhanced green fluorescent protein. For excitation wavelengths between 800 nm and 900 nm, TPA is best described by a single element, almost completely diagonal, two-dimensional (planar) transition tensor whose principal axis is collinear to that of the single-photon S 0 → S 1 transition moment. These observations are in accordance with assignments of the near-infrared two-photon absorption band in fluorescent proteins to a vibronically enhanced S 0 → S 1 transition.

Polarized two-photon photoselection in EGFP: Theory and experiment

Science.gov (United States)

Masters, T. A.; Marsh, R. J.; Blacker, T. S.; Armoogum, D. A.; Larijani, B.; Bain, A. J.

2018-04-01

In this work, we present a complete theoretical description of the excited state order created by two-photon photoselection from an isotropic ground state; this encompasses both the conventionally measured quadrupolar (K = 2) and the "hidden" degree of hexadecapolar (K = 4) transition dipole alignment, their dependence on the two-photon transition tensor and emission transition dipole moment orientation. Linearly and circularly polarized two-photon absorption (TPA) and time-resolved single- and two-photon fluorescence anisotropy measurements are used to determine the structure of the transition tensor in the deprotonated form of enhanced green fluorescent protein. For excitation wavelengths between 800 nm and 900 nm, TPA is best described by a single element, almost completely diagonal, two-dimensional (planar) transition tensor whose principal axis is collinear to that of the single-photon S0 → S1 transition moment. These observations are in accordance with assignments of the near-infrared two-photon absorption band in fluorescent proteins to a vibronically enhanced S0 → S1 transition.

Molecular photosensitisers for two-photon photodynamic therapy.

Science.gov (United States)

Bolze, F; Jenni, S; Sour, A; Heitz, V

2017-11-30

Two-photon excitation has attracted the attention of biologists, especially after the development of two-photon excited microscopy in the nineties. Since then, new applications have rapidly emerged such as the release of biologically active molecules and photodynamic therapy (PDT) using two-photon excitation. PDT, which requires a light-activated drug (photosensitiser), is a clinically approved and minimally invasive treatment for cancer and for non-malignant diseases. This feature article focuses on the engineering of molecular two-photon photosensitisers for PDT, which should bring important benefits to the treatment, increase the treatment penetration depth with near-infrared light excitation, improve the spatial selectivity and reduce the photodamage to healthy tissues. After an overview of the two-photon absorption phenomenon and the methods to evaluate two-photon induced phototoxicity on cell cultures, the different classes of photosensitisers described in the literature are discussed. The two-photon PDT performed with historical one-photon sensitisers are briefly presented, followed by specifically engineered cyclic tetrapyrrole photosensitisers, purely organic photosensitisers and transition metal complexes. Finally, targeted two-photon photosensitisers and theranostic agents that should enhance the selectivity and efficiency of the treatment are discussed.

Two-photon cooperative emission in the presence of athermal electromagnetic field

International Nuclear Information System (INIS)

Enaki, N.A.; Mihalache, D.

1997-01-01

The possibility of cooperative spontaneous two-photon emission of an extended radiators system and the influence of the external thermal electromagnetic field on the spontaneous emission rate, in such a system, are investigated. It is concluded that, in an external electromagnetic field, the two-photon cooperative emission rate increases significantly. The importance of this effect on the emission of gamma rays from inverted long-lived isomers triggered by X-ray thermal fields, is emphasized

Exciton molecule in semiconductors by two-photon absorption

International Nuclear Information System (INIS)

Arya, K.; Hassan, A.R.

1976-07-01

Direct creation of bi-exciton states by two-photon absorption in direct gap semiconductors is investigated theoretically. A numerical application to the case of CuCl shows that the two-photon absorption coefficient for bi-excitonic transitions is larger than that for two-photon interband transitions by three orders of magnitude. It becomes comparable to that for one-photon excitonic transitions for available laser intensities. The main contribution to this enhancement of the absorption coefficient for the transitions to the bi-exciton states is found to be from the resonance effect

Solution-dispersible Au nanocube dimers with greatly enhanced two-photon luminescence and SERS

Science.gov (United States)

Liu, Xiao-Li; Liang, Shan; Nan, Fan; Yang, Zhong-Jian; Yu, Xue-Feng; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

2013-05-01

We report the synthesis of 43-nm diameter Au nanocube dimers by using Ag+ ions as competitive ligands to freeze l-cysteine-induced assembly process of the nanocubes to a desirable stage. Ascribed to the resonant interparticle coupling with an newly arising plasmon band at 710 nm and local field enhancement, the two-photon luminescence intensity of the Au nanocube dimers in solution was over 20 times stronger than that of the monomers in the wavelength range 555-620 nm. Furthermore, by coupling Raman tags onto the nanocube surface, a solution-based surface-enhanced Raman scattering (SERS) of the nanocube dimers had an enhancement factor of over 10 times compared to the isolated nanocubes. To sum up, with high stability in solution and attractive optical properties, the Au nanocube dimers have potential applications in in vivo bio-imaging and solution-based SERS.We report the synthesis of 43-nm diameter Au nanocube dimers by using Ag+ ions as competitive ligands to freeze l-cysteine-induced assembly process of the nanocubes to a desirable stage. Ascribed to the resonant interparticle coupling with an newly arising plasmon band at 710 nm and local field enhancement, the two-photon luminescence intensity of the Au nanocube dimers in solution was over 20 times stronger than that of the monomers in the wavelength range 555-620 nm. Furthermore, by coupling Raman tags onto the nanocube surface, a solution-based surface-enhanced Raman scattering (SERS) of the nanocube dimers had an enhancement factor of over 10 times compared to the isolated nanocubes. To sum up, with high stability in solution and attractive optical properties, the Au nanocube dimers have potential applications in in vivo bio-imaging and solution-based SERS. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01170d

Limitations of two-level emitters as nonlinearities in two-photon controlled-PHASE gates

DEFF Research Database (Denmark)

Nysteen, Anders; McCutcheon, Dara P. S.; Heuck, Mikkel

2017-01-01

We investigate the origin of imperfections in the fidelity of a two-photon controlled-PHASE gate based on two-level-emitter nonlinearities. We focus on a passive system that operates without external modulations to enhance its performance. We demonstrate that the fidelity of the gate is limited...... by opposing requirements on the input pulse width for one-and two-photon-scattering events. For one-photon scattering, the spectral pulse width must be narrow compared with the emitter linewidth, while two-photon-scattering processes require the pulse width and emitter linewidth to be comparable. We find...

Photon-phonon-enhanced infrared rectification in a two-dimensional nanoantenna-coupled tunnel diode

International Nuclear Information System (INIS)

Kadlec, Emil A.; Jarecki, Robert L.; Starbuck, Andrew; Peters, David W.; Davids, Paul S.

2016-01-01

The interplay of strong infrared photon-phonon coupling with electromagnetic confinement in nanoscale devices is demonstrated to have a large impact on ultrafast photon-assisted tunneling in metal-oxide-semiconductor (MOS) structures. Infrared active optical phonon modes in polar oxides lead to strong dispersion and enhanced electric fields at material interfaces. We find that the infrared dispersion of SiO_2 near a longitudinal optical phonon mode can effectively impedance match a photonic surface mode into a nanoscale tunnel gap that results in large transverse-field confinement. An integrated 2D nanoantenna structure on a distributed large-area MOS tunnel-diode rectifier is designed and built to resonantly excite infrared surface modes and is shown to efficiently channel infrared radiation into nanometer-scale gaps in these MOS devices. This enhanced-gap transverse-electric field is converted to a rectified tunneling displacement current resulting in a dc photocurrent. We examine the angular and polarization-dependent spectral photocurrent response of these 2D nanoantenna-coupled tunnel diodes in the photon-enhanced tunneling spectral region. Lastly, our 2D nanoantenna-coupled infrared tunnel-diode rectifier promises to impact large-area thermal energy harvesting and infrared direct detectors.

Probabilistically cloning two single-photon states using weak cross-Kerr nonlinearities

International Nuclear Information System (INIS)

Zhang, Wen; Rui, Pinshu; Zhang, Ziyun; Yang, Qun

2014-01-01

By using quantum nondemolition detectors (QNDs) based on weak cross-Kerr nonlinearities, we propose an experimental scheme for achieving 1→2 probabilistic quantum cloning (PQC) of a single-photon state, secretly choosing from a two-state set. In our scheme, after a QND is performed on the to-be-cloned photon and the assistant photon, a single-photon projection measurement is performed by a polarization beam splitter (PBS) and two single-photon trigger detectors (SPTDs). The measurement is to judge whether the PQC should be continued. If the cloning fails, a cutoff is carried out and some operations are omitted. This makes our scheme economical. If the PQC is continued according to the measurement result, two more QNDs and some unitary operations are performed on the to-be-cloned photon and the cloning photon to achieve the PQC in a nearly deterministic way. Our experimental scheme for PQC is feasible for future technology. Furthermore, the quantum logic network of our PQC scheme is presented. In comparison with similar networks, our PQC network is simpler and more economical. (paper)

Pronounced enhancement of exciton Rabi oscillation for a two-photon transition based on quantum dot coupling control

International Nuclear Information System (INIS)

Luo Jian; Lu Di; Du Chaoling; Liu Youwen; Shi Daning; Lai Wei; Guo Chunlei; Gong Shangqing

2012-01-01

We theoretically investigate how to control the Rabi oscillation of excitons of the coupling quantum dots by manipulating static electric fields. Our results show that, for a single-photon process, when direct excitons change into indirect excitons with a bias applied on the sample, the Rabi oscillation rarely alters. However, for the two-photon process, a pronounced enhancement of Rabi oscillation is observed, which can be utilized as the logic gate in quantum information. (paper)

Bulky Counterions: Enhancing the Two-Photon Excited Fluorescence of Gold Nanoclusters.

Science.gov (United States)

Bertorelle, Franck; Moulin, Christophe; Soleilhac, Antonin; Comby-Zerbino, Clothilde; Dugourd, Philippe; Russier-Antoine, Isabelle; Brevet, Pierre-François; Antoine, Rodolphe

2018-01-19

Increasing fluorescence quantum yields of ligand-protected gold nanoclusters has attracted wide research interest. The strategy consisting in using bulky counterions has been found to dramatically enhance the fluorescence. In this Communication, we push forward this concept to the nonlinear optical regime. We show that by an appropriate choice of bulky counterions and of solvent, a 30-fold increase in two-photon excited fluorescence (TPEF) signal at ≈600 nm for gold nanoclusters can be obtained. This would correspond to a TPEF cross-section in the range of 0.1 to 1 GM. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Resonantly-enhanced two-photon ionization and mass-analyzed threshold ionization (MATI) spectroscopy of 2-hydroxypyridine

CERN Document Server

Lee, D H; Choi, K W; Choi, Y S; Kim, S K

2002-01-01

Mass-analyzed threshold ionization (MATI) spectra of 2-hydroxypyridines existing as lactims (2-pyridionl) in a molecular beam are obtained via (1+1') two-photon process to give accurate ionization energies of 8.9344 +- 0.0005 and 8.9284 +- 0.0005 eV for 2-pyridinol (2Py-OH) and its deuterated analogue (2Py-OD), respectively. Resonantly-enhanced two-photon ionization spectra of these compounds are also presented to give vibrational structures of their S sub 1 states. Vibrational frequencies of 2Py-OH and 2Py-OD in ionic ground states are accurately determined from MATI spectra taken via various S sub 1 intermediate states, and associated vibrational modes are assigned with the aid of ab initio calculations.

Level-1 trigger selection of electrons and photons with CMS for LHC Run-II.

CERN Document Server

AUTHOR|(CDS)2088114

2016-01-01

The CMS experiment has a sophisticated two-level online selection system that achieves a rejection factor of nearly $10^5$. The first, hardware-level trigger (L1) is based on coarse information coming from the calorimeters and the muon detectors while the High-Level Trigger combines fine-grain information from all subdetectors. During Run II, the LHC will increase its center of mass energy to 13 or 14 TeV, and progressively reach an instantaneous luminosity of $2\\times10^{34} \\mathrm{cm}^{-2}\\mathrm{s}^{-1}$. In order to guarantee a successful and ambitious physics programme in this intense environment, the CMS trigger and data acquisition system must be upgraded. The L1 calorimeter trigger hardware and architecture in particular has been redesigned to maintain the current thresholds even in presence of more demanding conditions (e.g., for electrons and photons) and improve the performance for the selection of $\\tau$ leptons. This design benefits from recent $\\mu$TCA technology, allowing sophisticated algorit...

Two-photon absorption of a supramolecular pseudoisocyanine J-aggregate assembly

International Nuclear Information System (INIS)

Belfield, Kevin D.; Bondar, Mykhailo V.; Hernandez, Florencio E.; Przhonska, Olga V.; Yao, Sheng

2006-01-01

Linear spectral properties, including excitation anisotropy, of pseudoisocyanine or 1,1'-diethyl-2,2'-cyanine iodide (PIC) J-aggregates in aqueous solutions with J-band position at 573 nm were investigated. Two-photon absorption of PIC J-aggregates and monomer molecules was studied using an open aperture Z-scan technique. A strong enhancement of the two-photon absorption cross-section of PIC in the supramolecular J-aggregate assembly was observed in aqueous solution. This enhancement is attributed to a strong coupling of the molecular transition dipoles. No two-photon absorption at the peak of the J-band was detected

Responsive block copolymer photonics triggered by protein-polyelectrolyte coacervation.

Science.gov (United States)

Fan, Yin; Tang, Shengchang; Thomas, Edwin L; Olsen, Bradley D

2014-11-25

Ionic interactions between proteins and polyelectrolytes are demonstrated as a method to trigger responsive transitions in block copolymer (BCP) photonic gels containing one neutral hydrophobic block and one cationic hydrophilic block. Poly(2-vinylpyridine) (P2VP) blocks in lamellar poly(styrene-b-2-vinylpyridine) block copolymer thin films are quaternized with primary bromides to yield swollen gels that show strong reflectivity peaks in the visible range; exposure to aqueous solutions of various proteins alters the swelling ratios of the quaternized P2VP (QP2VP) gel layers in the PS-QP2VP materials due to the ionic interactions between proteins and the polyelectrolyte. Parameters such as charge density, hydrophobicity, and cross-link density of the QP2VP gel layers as well as the charge and size of the proteins play significant roles on the photonic responses of the BCP gels. Differences in the size and pH-dependent charge of proteins provide a basis for fingerprinting proteins based on their temporal and equilibrium photonic response. The results demonstrate that the BCP gels and their photonic effect provide a robust and visually interpretable method to differentiate different proteins.

Giant enhancement of Kerr rotation in two-dimensional Bismuth iron garnet/Ag photonic crystals

International Nuclear Information System (INIS)

Liang Hong; Zhang Qiang; Liu Huan; Fu Shu-Fang; Zhou Sheng; Wang Xuan-Zhang

2015-01-01

Kerr effects of two-dimensional (2D) Bismuth iron garnet (BIG)/Ag photonic crystals (PCs) combined magnetic and plasmonic functionalities is investigated with the effective medium theory. An analytical expression of Kerr rotation angles is derived, in which the effects of the surface pasmons polaritons (SPP) on magneto–optical (MO) activities are reflected. The largest enhancement of Kerr rotation up to now is demonstrated, which is improved three orders of magnitude compared with that of BIG film. When λ < 750 nm all of the reflection are over 10% for the arbitrary filling ratio f 1 , in addition, the enhancement of Kerr rotation angles are at least one order of magnitude. (paper)

Enhancement of Solar Cell Efficiency for Space Applications Using Two-Dimensional Photonic Crystals

Directory of Open Access Journals (Sweden)

Postigo P.A.

2017-01-01

Full Text Available The effects of having a nanopatterned photonic crystal (PC structure in the surface of a solar cell can be usefully employed to increase the energy conversion efficiency, which may be critical for space applications. In this work, we have measured the reflectance (R and transmittance (T of thin InP layers (270 nm thick bonded to a glass substrate and nanopatterned with holes down to the glass in a triangular symmetry lattice separated by a lattice parameter a=450nm and maintaining a value of r/a=0.32. The optical spectra were measured with angular resolution in the range from 0.55 to 2.0 eV. There are noticeable changes in the spectra of the PC sample, with minima and maxima of the R and T clearly shifted with respect to the unpatterned sample, and new features that alter significantly the overall lineshape of each spectrum. Those features correspond in a first approximation to the well-known Fano-like resonances of the discrete photonic modes of the PC lattice and they have been used before to determine experimentally the position of the PC bands. The observed features can be translated to the optical absorption (A defined as A=1-R-T provided there are low or negligible scattering effects. The generated absorption spectra show enhancements above and below the electronic band edge of the InP that can be correlated with the photonic band structure. Even using a thicker semiconductor layer, the abovementioned effects can justify to use a photonic crystal front surface with sub-wavelength motifs. In this way, we have fabricated and characterized a complete Ge/InGaP solar cell with a 2D-PC on its front surface. An increase in the photocurrent up to a 8% was achieved on a solar cell with a 40% of its surface covered with a PC pattern. Enhancements of the external quantum efficiency (EQE of 22% for a wide range of wavelengths and up to a 46% for specific wavelengths have been measured, without use of any anti-reflection coating (ARC. A correlation

Two-photon Anderson localization in a disordered quadratic waveguide array

International Nuclear Information System (INIS)

Bai, Y F; Xu, P; Lu, L L; Zhong, M L; Zhu, S N

2016-01-01

We theoretically investigate two-photon Anderson localization in a χ (2) waveguide array with off-diagonal disorder. The nonlinear parametric down-conversion process would enhance both the single-photon and the two-photon Anderson localization. In the strong disorder regime, the two-photon position correlation exhibits a bunching distribution around the pumped waveguides, which is independent of pumping conditions and geometrical structures of waveguide arrays. Quadratic nonlinearity can be supplied as a new ingredient for Anderson localization. Also, our results pave the way for engineering quantum states through nonlinear quantum walks. (paper)

Uniform silica nanoparticles encapsulating two-photon absorbing fluorescent dye

International Nuclear Information System (INIS)

Wu Weibing; Liu Chang; Wang Mingliang; Huang Wei; Zhou Shengrui; Jiang Wei; Sun Yueming; Cui Yiping; Xu Chunxinag

2009-01-01

We have prepared uniform silica nanoparticles (NPs) doped with a two-photon absorbing zwitterionic hemicyanine dye by reverse microemulsion method. Obvious solvatochromism on the absorption spectra of dye-doped NPs indicates that solvents can partly penetrate into the silica matrix and then affect the ground and excited state of dye molecules. For dye-doped NP suspensions, both one-photon and two-photon excited fluorescence are much stronger and recorded at shorter wavelength compared to those of free dye solutions with comparative overall dye concentration. This behavior is possibly attributed to the restricted twisted intramolecular charge transfer (TICT), which reduces fluorescence quenching when dye molecules are trapped in the silica matrix. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells with low cytotoxicity. - Graphical abstract: Water-soluble silica NPs doped with a two-photon absorbing zwitterionic hemicyanine dye were prepared. They were found of enhanced one-photon and two-photon excited fluorescence compared to free dye solutions. Images from two-photon laser scanning fluorescence microscopy demonstrate that the dye-doped silica NPs can be actively uptaken by Hela cells.

Can Two-Photon Interference be Considered the Interference of Two Photons?

International Nuclear Information System (INIS)

Pittman, T.B.; Strekalov, D.V.; Migdall, A.; Rubin, M.H.; Sergienko, A.V.; Shih, Y.H.

1996-01-01

We report on a open-quote open-quote postponed compensation close-quote close-quote experiment in which the observed two-photon entangled state interference cannot be pictured in terms of the overlap of the two individual photon wave packets of a parametric down-conversion pair on a beam splitter. In the sense of a quantum eraser, the distinguishability of the different two-photon Feynman amplitudes leading to a coincidence detection is removed by delaying the compensation until after the output of an unbalanced two-photon interferometer. copyright 1996 The American Physical Society

Two-Photon Vibrational Spectroscopy using local optical fields of gold and silver nanostructures

Science.gov (United States)

Kneipp, Katrin; Kneipp, Janina; Kneipp, Harald

2007-03-01

Spectroscopic effects can be strongly affected when they take place in the immediate vicinity of metal nanostructures due to coupling to surface plasmons. We introduce a new approach that suggests highly efficient two-photon labels as well as two-photon vibrational spectroscopy for non-destructive chemical probing. The underlying spectroscopic effect is the incoherent inelastic scattering of two photons on the vibrational quantum states performed in the enhanced local optical fields of gold nanoparticles, surface enhanced hyper Raman scattering (SEHRS). We infer effective two-photon cross sections for SEHRS on the order of 10^5 GM, similar or higher than the best known cross sections for two-photon fluorescence. SEHRS combines the advantages of two-photon spectroscopy with the structural information of vibrational spectroscopy, and the high sensitivity and nanometer-scale local confinement of plasmonics-based spectroscopy.

Applications of two-photon fluorescence microscopy in deep-tissue imaging

Science.gov (United States)

Dong, Chen-Yuan; Yu, Betty; Hsu, Lily L.; Kaplan, Peter D.; Blankschstein, D.; Langer, Robert; So, Peter T. C.

2000-07-01

Based on the non-linear excitation of fluorescence molecules, two-photon fluorescence microscopy has become a significant new tool for biological imaging. The point-like excitation characteristic of this technique enhances image quality by the virtual elimination of off-focal fluorescence. Furthermore, sample photodamage is greatly reduced because fluorescence excitation is limited to the focal region. For deep tissue imaging, two-photon microscopy has the additional benefit in the greatly improved imaging depth penetration. Since the near- infrared laser sources used in two-photon microscopy scatter less than their UV/glue-green counterparts, in-depth imaging of highly scattering specimen can be greatly improved. In this work, we will present data characterizing both the imaging characteristics (point-spread-functions) and tissue samples (skin) images using this novel technology. In particular, we will demonstrate how blind deconvolution can be used further improve two-photon image quality and how this technique can be used to study mechanisms of chemically-enhanced, transdermal drug delivery.

Highly sensitive measurement in two-photon absorption cross section and investigation of the mechanism of two-photon-induced polymerization

Energy Technology Data Exchange (ETDEWEB)

Lu Youmei E-mail: luym19@cc.tuat.ac.jp; Hasegawa, Fuyuki; Goto, Takamichi; Ohkuma, Satoshi; Fukuhara, Setsuko; Kawazu, Yukie; Totani, Kenro; Yamashita, Takashi; Watanabe, Toshiyuki E-mail: toshi@cc.tuat.ac.jp

2004-10-01

A novel two-photon initiator, 4,4'-bis[4-(di-n-butylamino)styryl]-benzene with the side-group methyl (Me) (abbreviated as Chromophore 1), was synthesized in comparison with the chromophore with the side group methoxy (MeO) (abbreviated as Chromophore 2). Femtosecond laser-induced fluorescence intensity was used to evaluate two-photon absorption (TPA) cross section, {delta}, by means of a charge-coupled device, USB-2000 (abbreviated as CCD). Results showed that changing the side group from Me to MeO led to a significant red-shift of the two-photon absorption ({sup 2}{lambda}{sub max}). However, the microstructures obtained by two-photon-induced polymerization (TPIP) demonstrated that the sensitivities of Chromophore 1 increased despite a two-fold decrease in the two-photon cross section {delta}{sub max,} relative to Chromophore 2. Correlated with the appearance that the long-lived charge transfer emission of the chromophore in the monomer bulk, we suggest that the intramolecular charge transfer (intra-CT) takes place within the excited dye. Then intermolecular charge transfer was successive as a result of the formation of an exciplex between the dye and the monomer. The Me group was favorable for the intra-CT, relative to MeO, which contributed to the enhancement of the sensitivity of TPIP.

Doppler-free two-photon excitation of 238U

International Nuclear Information System (INIS)

Hodgkinson, D.P.; Wort, D.J.H.

1981-04-01

A theory of resonantly enhanced two-photon absorption is presented and tested in a number of experiments in which 238 U vapour is excited by two continuous wave dye lasers. Good quantitative agreement between theory and experiment is found. In particular the central prediction of the theory, that antiparallel laser beams of modest intensity can pump an appreciable fraction of the Maxwell velocity distribution, has been checked directly by measuring the spectral width of the fluorescence from the two-photon excited level. (author)

Standardisation of liver MDCT by tracking liver parenchyma enhancement to trigger imaging

International Nuclear Information System (INIS)

Brodoefel, H.; Tognolini, A.; Zamboni, G.A.; Gourtsoyianni, S.; Raptopoulos, V.; Claussen, C.D.

2012-01-01

To assess parenchymal bolus-triggering in terms of liver enhancement, lesion-to-liver conspicuity and inter-image variability across serial follow-up MDCTs. We reviewed MDCTs of 50 patients with hepatic metastases who had a baseline CT and two follow-up examinations. In 25 consecutive patients CT data acquisition was initiated by liver parenchyma triggering at a 50-HU enhancement threshold. In a matched control group, imaging was performed with an empirical delay of 65 s. CT attenuation values were assessed in vessels, liver parenchyma and metastasis. Target lesions were classified according to five enhancement patterns. Compared with the control group, liver enhancement was significantly higher with parenchyma triggering (59.8 ± 7.6 HU vs. 48.8 ± 11.2 HU, P = 0.0002). The same was true for conspicuity (liver parenchyma - lesion attenuation) of hypo-enhancing lesions (72.2 ± 15.9 HU vs. 52.7 ± 19.4 HU, P = 0.0006). Liver triggering was associated with reduced variability for liver enhancement among different patients (P = 0.035) and across serial follow-up examinations in individual patients (P < 0.0001). The number of patients presenting with uniform lesion enhancement pattern across serial examinations was significantly higher in the triggered group (20 vs. 11; P = 0.018). Liver parenchyma triggering provides superior lesion conspicuity and improves standardisation of image quality across follow-up examinations with greater uniformity of enhancement patterns. (orig.)

Excitation enhancement and extraction enhancement with photonic crystals

Science.gov (United States)

Shapira, Ofer; Soljacic, Marin; Zhen, Bo; Chua, Song-Liang; Lee, Jeongwon; Joannopoulos, John

2015-03-03

Disclosed herein is a system for stimulating emission from at least one an emitter, such as a quantum dot or organic molecule, on the surface of a photonic crystal comprising a patterned dielectric substrate. Embodiments of this system include a laser or other source that illuminates the emitter and the photonic crystal, which is characterized by an energy band structure exhibiting a Fano resonance, from a first angle so as to stimulate the emission from the emitter at a second angle. The coupling between the photonic crystal and the emitter may result in spectral and angular enhancement of the emission through excitation and extraction enhancement. These enhancement mechanisms also reduce the emitter's lasing threshold. For instance, these enhancement mechanisms enable lasing of a 100 nm thick layer of diluted organic molecules solution with reduced threshold intensity. This reduction in lasing threshold enables more efficient organic light emitting devices and more sensitive molecular sensing.

Two-photon spin generation and detection

International Nuclear Information System (INIS)

Miah, M Idrish

2009-01-01

A time- and polarization-resolved two-photon pump-probe investigation is performed in lightly doped GaAs. We generate spin-polarized electrons in bulk GaAs at various temperatures using right-circularly polarized two-photon excitation and detect them by probing the spin-dependent transmission of the sample. The spin polarization (P) of conduction band electrons, as measured using probe pulses with the same (right) and opposite (left) circular polarization, is measured in dependences of pump-probe delay (Δt), lattice temperature (T L ), doping density (n) as well as of the excess photon energy ΔE 2ω = ℎ2ω - E g , where E g is the band gap energy. P is found to be decayed with Δt and enhanced with the decrease in T L or the increase in n. It is also found that P decreases with the increase in ΔE 2ω and depolarizes rapidly for ΔE 2ω > ΔE SO , where ΔE SO is the spin-orbit splitting energy. The results demonstrate that due to a much longer absorption depth highly polarized spins can be generated optically by two-photon pumping of bulk semiconductors.

Two-photon physics

International Nuclear Information System (INIS)

Bardeen, W.A.

1981-10-01

A new experimental frontier has recently been opened to the study of two photon processes. The first results of many aspects of these reactions are being presented at this conference. In contrast, the theoretical development of research ito two photon processes has a much longer history. This talk reviews the many different theoretical ideas which provide a detailed framework for our understanding of two photon processes

Two photon versus one photon fluorescence excitation in whispering gallery mode microresonators

International Nuclear Information System (INIS)

Pastells, Carme; Marco, M.-Pilar; Merino, David; Loza-Alvarez, Pablo; Pasquardini, Laura; Lunelli, Lorenzo; Pederzolli, Cecilia; Daldosso, Nicola; Farnesi, Daniele; Berneschi, Simone; Righini, Giancarlo C.; Quercioli, Franco; Nunzi Conti, Gualtiero; Soria, Silvia

2016-01-01

We investigate the feasibility of both one photon and two photon fluorescence excitation using whispering gallery mode microresonators. We report the linear and non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a silica whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also investigate the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are dylight800, tetramethyl rhodamine isothiocyanate, rhodamine 6G and fluorescein. All measurements were performed in a modified confocal microscope. - Highlights: • One photon fluorescence overlaps with the semiconductor pump laser gain bandwidth. • We report on the feasibility to excite two photon fluorescence in microbubble resonators. • Our functionalization process maintains a good quality factor of the microresonator.

Two photon versus one photon fluorescence excitation in whispering gallery mode microresonators

Energy Technology Data Exchange (ETDEWEB)

Pastells, Carme; Marco, M.-Pilar [Nanobiotechnology for Diagnostics Group (Nb4Dg), IQAC-CSIC, 08034 Barcelona (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, 08034 Barcelona (Spain); Merino, David; Loza-Alvarez, Pablo [ICFO-Institut de Ciències Fotòniques, Castelldefels, 08860 Barcelona (Spain); Pasquardini, Laura [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); Lunelli, Lorenzo [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); IBF-CNR, 38123 Povo, TN (Italy); Pederzolli, Cecilia [Fondazione Bruno Kessler, 38123 Povo, TN (Italy); Daldosso, Nicola [Department of Computer Science, University of Verona, Strada le Grazie 15, 37134 Verona (Italy); Farnesi, Daniele [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, 00184 Roma (Italy); Berneschi, Simone [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Righini, Giancarlo C. [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, 00184 Roma (Italy); Quercioli, Franco [CNR-INO National Institute of Optics, Sesto Fiorentino, FI (Italy); Nunzi Conti, Gualtiero [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy); Soria, Silvia, E-mail: s.soria@ifac.cnr.it [CNR-IFAC “Nello Carrara” Institute of Applied Physics, 50019 Sesto Fiorentino, FI (Italy)

2016-02-15

We investigate the feasibility of both one photon and two photon fluorescence excitation using whispering gallery mode microresonators. We report the linear and non linear fluorescence real-time detection of labeled IgG covalently bonded to the surface of a silica whispering gallery mode resonator (WGMR). The immunoreagents have been immobilized onto the surface of the WGMR sensor after being activated with an epoxy silane and an orienting layer. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of immunoreactions. We also investigate the potential of microbubbles as nonlinear enhancement platform. The dyes used in these studies are dylight800, tetramethyl rhodamine isothiocyanate, rhodamine 6G and fluorescein. All measurements were performed in a modified confocal microscope. - Highlights: • One photon fluorescence overlaps with the semiconductor pump laser gain bandwidth. • We report on the feasibility to excite two photon fluorescence in microbubble resonators. • Our functionalization process maintains a good quality factor of the microresonator.

Two-photon exchange in elastic electron-nucleon scattering

International Nuclear Information System (INIS)

Blunden, P.G.; Melnitchouk, W.; Tjon, J.A.

2005-01-01

A detailed study of two-photon exchange in unpolarized and polarized elastic electron-nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are found to have a strong angular dependence, which leads to a partial resolution of the discrepancy between the Rosenbluth and polarization transfer measurements of the proton electric to magnetic form factor ratio, G E /G M . The two-photon exchange contribution to the longitudinal polarization transfer P L is small, whereas the contribution to the transverse polarization transfer P T is enhanced at backward angles by several percent, increasing with Q 2 . This gives rise to a small, E /G M obtained from the polarization transfer ratio P T /P L at large Q 2 . We also compare the two-photon exchange effects with data on the ratio of e + p to e - p cross sections, which is predicted to be enhanced at backward angles. Finally, we evaluate the corrections to the form factors of the neutron and estimate the elastic intermediate state contribution to the 3 He form factors

The Upgrade of the ATLAS Electron and Photon Triggers for LHC Run 2 and their Performance

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00220717; The ATLAS collaboration

2016-01-01

Electron and photon triggers covering transverse energies from 5 GeV to several TeV are essential for signal selection in a wide variety of ATLAS physics analyses to study Standard Model processes and to search for new phenomena. Final states including leptons and photons had, for example, an important role in the discovery and measurement of the Higgs particle. Dedicated triggers are also used to collect data for calibration, efficiency and fake rate measurements. The ATLAS trigger system is divided in a hardware-based (Level 1) and a software based high level trigger (HLT), both of which were upgraded during the long shutdown of the LHC in preparation for data taking at $\\sqrt{s}$ = 13TeV. The increasing luminosity and more challenging pile-up conditions as well as the planned higher center-of-mass energy demanded the optimisation of the trigger selections at each level, to control the rates and keep efficiencies high. To improve the performance multivariate analysis techniques are introduced at the HLT. Th...

A multifunctional magnetic nanocarrier bearing fluorescent dye for targeted drug delivery by enhanced two-photon triggered release

International Nuclear Information System (INIS)

Banerjee, Shashwat S; Chen, D-H

2009-01-01

We report a novel nanoformulation for targeted drug delivery which utilizes nanophotonics through the fusion of nanotechnology with biomedical application. The approach involves an energy-transferring magnetic nanoscopic co-assembly fabricated of rhodamine B (RDB) fluorescent dye grafted gum arabic modified Fe 3 O 4 magnetic nanoparticle and photosensitive linker by which dexamethasone drug is conjugated to the magnetic nano-assembly. The advantage offered by this nanoformulation is the indirect photo-triggered-on-demand drug release by efficient up-converting energy of the near-IR (NIR) light to higher energy and intraparticle energy transfer from the dye grafted magnetic nanoparticle to the linker for drug release by cleavage. The synthesized nanoparticles were found to be of ultra-small size (13.33 nm) and are monodispersed in an aqueous suspension. Dexamethasone (Dexa) drug conjugated to RDB-GAMNP by photosensitive linker showed appreciable release of Dexa by photo-triggered response on exposure to radiation having a wavelength in the NIR region whereas no detectable release was observed in the dark. Photo-triggered response for the nanoformulation not bearing the rhodamine B dye was drastically less as less Dexa was released on exposure to NIR radiation which suggest that the photo-cleavage of linker and release of Dexa mainly originated from the indirect excitation through the uphill energy conversions based on donor-acceptor model FRET. The promising pathway of nanophotonics for the on-demand release of the drug makes this nanocarrier very promising for applications in nanomedicine.

Enhanced axion-photon coupling in GUT with hidden photon

Science.gov (United States)

Daido, Ryuji; Takahashi, Fuminobu; Yokozaki, Norimi

2018-05-01

We show that the axion coupling to photons can be enhanced in simple models with a single Peccei-Quinn field, if the gauge coupling unification is realized by a large kinetic mixing χ = O (0.1) between hypercharge and unbroken hidden U(1)H. The key observation is that the U(1)H gauge coupling should be rather strong to induce such large kinetic mixing, leading to enhanced contributions of hidden matter fields to the electromagnetic anomaly. We find that the axion-photon coupling is enhanced by about a factor of 10-100 with respect to the GUT-axion models with E / N = 8 / 3.

Identification of CW two-photon transitions in Na2 and NaK

International Nuclear Information System (INIS)

Morgan, G.P.

1983-01-01

This thesis reports on the two-photon visible excitation spectra of sodium and potassium vapors. In the past, similar work has been performed on sodium and many atomic two-photon transitions have been characterized. However, many extra signals exist which do not possess the ground, 3S, state hyperfine splitting. These extra transitions are due to the sodium dimer Na 2 . 79 such transitions, from 5800A - 6500A, which lie within the resolution of the apparatus have been studied. The molecules are excited with a lowpower narrow band counterpropagating cw dye laser beam and two-photon fluorescence. The fluorescence intensities of many of these transitions are greater than the 3S to 5S and 3S to 4D atomic signals, where the 3P enhancing state lies 300 cm -1 from resonance. By comparing the number density of the atomic with any molecular ground state and also the two-photon transition rates to excited states, the intermediate enhancing state for a two-photon transition in Na 2 can be predicted to be less than 1 cm -1 from resonance with the two-photon transition. This observation, along with published Dunham coefficients, is used to identify the states involved in the two-photon transitions

Two-photon spin generation and detection

Energy Technology Data Exchange (ETDEWEB)

Miah, M Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)

2009-02-21

A time- and polarization-resolved two-photon pump-probe investigation is performed in lightly doped GaAs. We generate spin-polarized electrons in bulk GaAs at various temperatures using right-circularly polarized two-photon excitation and detect them by probing the spin-dependent transmission of the sample. The spin polarization (P) of conduction band electrons, as measured using probe pulses with the same (right) and opposite (left) circular polarization, is measured in dependences of pump-probe delay ({Delta}t), lattice temperature (T{sub L}), doping density (n) as well as of the excess photon energy {Delta}E{sub 2{omega}}= {h_bar}2{omega} - E{sub g}, where E{sub g} is the band gap energy. P is found to be decayed with {Delta}t and enhanced with the decrease in T{sub L} or the increase in n. It is also found that P decreases with the increase in {Delta}E{sub 2{omega}}and depolarizes rapidly for {Delta}E{sub 2{omega}}> {Delta}E{sub SO}, where {Delta}E{sub SO} is the spin-orbit splitting energy. The results demonstrate that due to a much longer absorption depth highly polarized spins can be generated optically by two-photon pumping of bulk semiconductors.

Optical microcavities based on surface modes in two-dimensional photonic crystals and silicon-on-insulator photonic crystals

DEFF Research Database (Denmark)

Xiao, Sanshui; Qiu, M.

2007-01-01

Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor is gr...... is gradually enhanced and the resonant frequency converges to that of the corresponding surface mode in the photonic crystals. These structures have potential applications such as sensing.......Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor...

Two-photon patterning of a polymer containing Y-shaped azochromophores

International Nuclear Information System (INIS)

Ambrosio, A.; Orabona, E.; Maddalena, P.; Camposeo, A.; Polo, M.; Neves, A. A. R.; Pisignano, D.; Carella, A.; Borbone, F.; Roviello, A.

2009-01-01

We report on the patterning of the free surface of azo-based polymer films by means of mass migration driven by one- or two-photon absorption. A symmetric donor-acceptor-donor structured Y-shaped azochromophore is specifically synthesized to enhance two-photon absorption in the polymer. The exposure of the polymer film to a focused laser beam results in light-driven mass migration for both one- and two-photon absorptions. Features with subdiffraction resolution (250 nm) are realized and the patterning dynamics is investigated as a function of the light dose. Furthermore, functional photonic structures, such as diffraction gratings with periods ranging between 0.5 and 2.0 μm, have been realized

Enhancement of Raman scattering from monolayer graphene by photonic crystal nanocavities

Science.gov (United States)

Kimura, Issei; Yoshida, Masahiro; Sota, Masaki; Inoue, Taiki; Chiashi, Shohei; Maruyama, Shigeo; Kato, Yuichiro K.

Monolayer graphene is an atomically thin two-dimensional material that shows strong Raman scattering, while photonic crystal nanocavities with small mode volumes allow for efficient optical coupling at the nanoscale. Here we demonstrate resonant enhancement of graphene Raman G' band by coupling to photonic crystal cavity modes. Hexagonal-lattice photonic crystal L3 cavities are fabricated from silicon-on-insulator substrates. and monolayer graphene sheets grown by chemical vapor deposition are transferred onto the nanocavities. Excitation wavelength dependence of Raman spectra show that the Raman intensity is enhanced when the G' peak is in resonance with the cavity mode. By performing imaging measurements, we confirm that such an enhancement is only observed at the cavity position. Work supported by JSPS KAKENHI Grant Numbers JP16K13613, JP25107002 and MEXT (Photon Frontier Network Program, Nanotechnology Platform).

Phosphorescent probes for two-photon microscopy of oxygen (Conference Presentation)

Science.gov (United States)

Vinogradov, Sergei A.; Esipova, Tatiana V.

2016-03-01

The ability to quantify oxygen in vivo in 3D with high spatial and temporal resolution is much needed in many areas of biological research. Our laboratory has been developing the phosphorescence quenching technique for biological oximetry - an optical method that possesses intrinsic microscopic capability. In the past we have developed dendritically protected oxygen probes for quantitative imaging of oxygen in tissue. More recently we expanded our design on special two-photon enhanced phosphorescent probes. These molecules brought about first demonstrations of the two-photon phosphorescence lifetime microscopy (2PLM) of oxygen in vivo, providing new information for neouroscience and stem cell biology. However, current two-photon oxygen probes suffer from a number of limitations, such as sub-optimal brightness and high cost of synthesis, which dramatically reduce imaging performance and limit usability of the method. In this paper we discuss principles of 2PLM and address the interplay between the probe chemistry, photophysics and spatial and temporal imaging resolution. We then present a new approach to brightly phosphorescent chromophores with internally enhanced two-photon absorption cross-sections, which pave a way to a new generation of 2PLM probes.

FocusStack and StimServer: a new open source MATLAB toolchain for visual stimulation and analysis of two-photon calcium neuronal imaging data.

Science.gov (United States)

Muir, Dylan R; Kampa, Björn M

2014-01-01

Two-photon calcium imaging of neuronal responses is an increasingly accessible technology for probing population responses in cortex at single cell resolution, and with reasonable and improving temporal resolution. However, analysis of two-photon data is usually performed using ad-hoc solutions. To date, no publicly available software exists for straightforward analysis of stimulus-triggered two-photon imaging experiments. In addition, the increasing data rates of two-photon acquisition systems imply increasing cost of computing hardware required for in-memory analysis. Here we present a Matlab toolbox, FocusStack, for simple and efficient analysis of two-photon calcium imaging stacks on consumer-level hardware, with minimal memory footprint. We also present a Matlab toolbox, StimServer, for generation and sequencing of visual stimuli, designed to be triggered over a network link from a two-photon acquisition system. FocusStack is compatible out of the box with several existing two-photon acquisition systems, and is simple to adapt to arbitrary binary file formats. Analysis tools such as stack alignment for movement correction, automated cell detection and peri-stimulus time histograms are already provided, and further tools can be easily incorporated. Both packages are available as publicly-accessible source-code repositories.

Tale of two photons

International Nuclear Information System (INIS)

Anon.

1994-01-01

A very profitable spinoff from electron- positron collisions is two-photon physics. Rather than the electron and positron interacting directly via an exchanged photon, two virtual (transient) photons, one from each particle, get tangled up. With new electron-positron colliders appearing on the scene, a topical meeting on two-photon physics - 'From DAPHNE to LEP 200 and beyond' - held from 2-4 February in Paris, in the premises of the Ministry of Higher Education and Research, was particularly timely. Some 60 physicists, both experimentalists and theorists, participated, with some thirty speakers

Photonic Structure-Integrated Two-Dimensional Material Optoelectronics

Directory of Open Access Journals (Sweden)

Tianjiao Wang

2016-12-01

Full Text Available The rapid development and unique properties of two-dimensional (2D materials, such as graphene, phosphorene and transition metal dichalcogenides enable them to become intriguing candidates for future optoelectronic applications. To maximize the potential of 2D material-based optoelectronics, various photonic structures are integrated to form photonic structure/2D material hybrid systems so that the device performance can be manipulated in controllable ways. Here, we first introduce the photocurrent-generation mechanisms of 2D material-based optoelectronics and their performance. We then offer an overview and evaluation of the state-of-the-art of hybrid systems, where 2D material optoelectronics are integrated with photonic structures, especially plasmonic nanostructures, photonic waveguides and crystals. By combining with those photonic structures, the performance of 2D material optoelectronics can be further enhanced, and on the other side, a high-performance modulator can be achieved by electrostatically tuning 2D materials. Finally, 2D material-based photodetector can also become an efficient probe to learn the light-matter interactions of photonic structures. Those hybrid systems combine the advantages of 2D materials and photonic structures, providing further capacity for high-performance optoelectronics.

Two-photon interference of polarization-entangled photons in a Franson interferometer.

Science.gov (United States)

Kim, Heonoh; Lee, Sang Min; Kwon, Osung; Moon, Han Seb

2017-07-18

We present two-photon interference experiments with polarization-entangled photon pairs in a polarization-based Franson-type interferometer. Although the two photons do not meet at a common beamsplitter, a phase-insensitive Hong-Ou-Mandel type two-photon interference peak and dip fringes are observed, resulting from the two-photon interference effect between two indistinguishable two-photon probability amplitudes leading to a coincidence detection. A spatial quantum beating fringe is also measured for nondegenerate photon pairs in the same interferometer, although the two-photon states have no frequency entanglement. When unentangled polarization-correlated photons are used as an input state, the polarization entanglement is successfully recovered through the interferometer via delayed compensation.

Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

Science.gov (United States)

Johansson, S; Letokhov, V

2001-01-26

One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium.

Imaging Live Drosophila Brain with Two-Photon Fluorescence Microscopy

Science.gov (United States)

Ahmed, Syeed Ehsan

Two-photon fluorescence microscopy is an imaging technique which delivers distinct benefits for in vivo cellular and molecular imaging. Cyclic adenosine monophosphate (cAMP), a second messenger molecule, is responsible for triggering many physiological changes in neural system. However, the mechanism by which this molecule regulates responses in neuron cells is not yet clearly understood. When cAMP binds to a target protein, it changes the structure of that protein. Therefore, studying this molecular structure change with fluorescence resonance energy transfer (FRET) imaging can shed light on the cAMP functioning mechanism. FRET is a non-radiative dipole-dipole coupling which is sensitive to small distance change in nanometer scale. In this study we have investigated the effect of dopamine in cAMP dynamics in vivo. In our study two-photon fluorescence microscope was used for imaging mushroom bodies inside live Drosophila melanogaster brain and we developed a method for studying the change in cyclic AMP level.

Two-photon luminescence microscopy of field enhancement at gold nanoparticles

DEFF Research Database (Denmark)

Beermann, Jonas; Bozhevolnyi, Sergey I.

2005-01-01

Using a reflection scanning optical microscope detecting two-photon luminescence (TPL) we have imaged square gold bumps positioned in a periodic array either on a smooth gold film or directly on a glass substrate. The second-harmonic (SH) and TPL response from these structures show both...

One-, two- and three-photon spectroscopy of π-conjugated dendrimers: cooperative enhancement and coherent domains

International Nuclear Information System (INIS)

Drobizhev, M.; Rebane, A.; Suo, Z.; Spangler, C.W.

2005-01-01

We use wavelength tunable femtosecond pulses to measure intrinsic (simultaneous) two-photon absorption (2PA) and three-photon absorption (3PA) molecular cross section in two series of π-conjugated dendrimers built of identical 4,4'-bis(diphenylamino) stilbene (BDPAS) and 4,4'-bis(diphenylamino) distyrylbenzene (BDPADSB) repeat units. Record large 2PA cross sections, σ 2 =10 -46 cm 4 s are obtained for the largest second-generation BDPAS-based dendrimer, as well as zeroth-generation 4-arm BDPADSB-based dendrimer. In both series, maximum 2PA cross section increases nonlinearly with the number of π-electrons, whereas for higher generations this dependence turns to linear one. 3PA cross section also increases nonlinearly with the size of the system in the series of BDPAS-based molecules, amounting a record large value, σ 3 =10 -79 cm 6 s 2 , for the largest, second-generation dendrimer. We interpret these results in terms of direct inter-branch conjugation, which facilitates cooperative enhancement of the nonlinear-optical response. We propose a simple model which allows us to determine the effective size of coherent domains (extent of conjugation), which, in turn, determines the optimum dendrimer size for most efficient nonlinear response

Two-photon transitions in hydrogen atoms embedded in weakly coupled plasmas

International Nuclear Information System (INIS)

Paul, S.; Ho, Y. K.

2008-01-01

The pseudostate method has been applied to calculate energy eigenvalues and corresponding eigenfunctions of the hydrogen atom in Debye plasma environments. Resonant two-photon transition rates from the ground state of atomic hydrogen to 2s and 3s excited states have been computed as a function of photon frequency in the length and velocity gauges for different Debye lengths. A two-photon transparency is found in correspondence to each resonance for 1s-3s. The transparency frequency and resonance enhancement frequency vary significantly with the Debye length.

Experimental two-dimensional quantum walk on a photonic chip.

Science.gov (United States)

Tang, Hao; Lin, Xiao-Feng; Feng, Zhen; Chen, Jing-Yuan; Gao, Jun; Sun, Ke; Wang, Chao-Yue; Lai, Peng-Cheng; Xu, Xiao-Yun; Wang, Yao; Qiao, Lu-Feng; Yang, Ai-Lin; Jin, Xian-Min

2018-05-01

Quantum walks, in virtue of the coherent superposition and quantum interference, have exponential superiority over their classical counterpart in applications of quantum searching and quantum simulation. The quantum-enhanced power is highly related to the state space of quantum walks, which can be expanded by enlarging the photon number and/or the dimensions of the evolution network, but the former is considerably challenging due to probabilistic generation of single photons and multiplicative loss. We demonstrate a two-dimensional continuous-time quantum walk by using the external geometry of photonic waveguide arrays, rather than the inner degree of freedoms of photons. Using femtosecond laser direct writing, we construct a large-scale three-dimensional structure that forms a two-dimensional lattice with up to 49 × 49 nodes on a photonic chip. We demonstrate spatial two-dimensional quantum walks using heralded single photons and single photon-level imaging. We analyze the quantum transport properties via observing the ballistic evolution pattern and the variance profile, which agree well with simulation results. We further reveal the transient nature that is the unique feature for quantum walks of beyond one dimension. An architecture that allows a quantum walk to freely evolve in all directions and at a large scale, combining with defect and disorder control, may bring up powerful and versatile quantum walk machines for classically intractable problems.

Enhancing photon squeezing one leviton at a time

Science.gov (United States)

Ferraro, D.; Ronetti, F.; Rech, J.; Jonckheere, T.; Sassetti, M.; Martin, T.

2018-04-01

A mesoscopic device in the simple tunnel junction or quantum point contact geometry emits microwaves with remarkable quantum properties, when subjected to a sinusoidal drive in the GHz range. In particular, single and two-photon squeezing as well as entanglement in the frequency domain have been reported. By revising the photoassisted noise analysis developed in the framework of electron quantum optics, we present a detailed comparison between the cosine drive case and other experimentally relevant periodic voltages such as rectangular and Lorentzian pulses. We show that the latter drive is the best candidate in order to enhance quantum features and purity of the outgoing single and two-photon states, a noteworthy result in a quantum information perspective.

Two-dimensional topological photonics

Science.gov (United States)

Khanikaev, Alexander B.; Shvets, Gennady

2017-12-01

Originating from the studies of two-dimensional condensed-matter states, the concept of topological order has recently been expanded to other fields of physics and engineering, particularly optics and photonics. Topological photonic structures have already overturned some of the traditional views on wave propagation and manipulation. The application of topological concepts to guided wave propagation has enabled novel photonic devices, such as reflection-free sharply bent waveguides, robust delay lines, spin-polarized switches and non-reciprocal devices. Discrete degrees of freedom, widely used in condensed-matter physics, such as spin and valley, are now entering the realm of photonics. In this Review, we summarize the latest advances in this highly dynamic field, with special emphasis on the experimental work on two-dimensional photonic topological structures.

Doppler-free two-photon spectroscopy of Yb atoms and efficient generation of a cascade of two photons at 611.3 nm and 555.8 nm

International Nuclear Information System (INIS)

Song, Minsoo; Yoon, Duseong; Yoon, Taihyun

2011-01-01

We performed high-resolution Doppler-free two-photon spectroscopy of Yb atoms in an effusive atomic beam and generated a cascade of two photons at 611.3 nm (idler) and 555.8 nm (signal) with a narrow bandwidth of 37 MHz. Efficient population transfer from the ground state (6s 2 1 S 0 ) to the upper state (6s7s 1 S 0 ), where direct transition at 291.1 nm is dipole forbidden, was achieved through a resonant two-photon excitation enhanced by the electromagnetically-induced transparency mediated by the intermediate state (6s6p 1 P 1 ). From the upper state, a cascade of two photons in sequence was emitted via the spin triplet state (6s 2 3 P 1 ). Numerical calculations of the density matrix equations taking into account the residual Doppler effect and strong driving fields explain quantitatively the experimental results for the dependences of the idler and the signal beam intensities on the various parameters of the driving fields. We report on the generation of a cascade of two photons with fluxes at the level of a few times 10 6 photons/s detected at a solid angle of 0.01 sr.

Doppler-free two-photon spectroscopy of Yb atoms and efficient generation of a cascade of two photons at 611.3 nm and 555.8 nm

Energy Technology Data Exchange (ETDEWEB)

Song, Minsoo; Yoon, Duseong; Yoon, Taihyun [Korea University, Seoul (Korea, Republic of)

2011-10-15

We performed high-resolution Doppler-free two-photon spectroscopy of Yb atoms in an effusive atomic beam and generated a cascade of two photons at 611.3 nm (idler) and 555.8 nm (signal) with a narrow bandwidth of 37 MHz. Efficient population transfer from the ground state (6s{sup 2} {sup 1}S{sub 0}) to the upper state (6s7s {sup 1}S{sub 0}), where direct transition at 291.1 nm is dipole forbidden, was achieved through a resonant two-photon excitation enhanced by the electromagnetically-induced transparency mediated by the intermediate state (6s6p {sup 1}P{sub 1}). From the upper state, a cascade of two photons in sequence was emitted via the spin triplet state (6s{sup 2} {sup 3}P{sub 1}). Numerical calculations of the density matrix equations taking into account the residual Doppler effect and strong driving fields explain quantitatively the experimental results for the dependences of the idler and the signal beam intensities on the various parameters of the driving fields. We report on the generation of a cascade of two photons with fluxes at the level of a few times 10{sup 6} photons/s detected at a solid angle of 0.01 sr.

Two-photon excited autofluorescence imaging of human retinal pigment epithelial cells

Science.gov (United States)

Han, Meng; Blindewald-Wittich, Almut; Holz, Frank G.; Giese, Günter; Niemz, Markolf H.; Snyder, Sarah; Sun, Hui; Yu, Jiayi; Agopov, Michael; La Schiazza, Olivier; Bille, Josef F.

2006-01-01

Degeneration of retinal pigment epithelial (RPE) cells severely impairs the visual function of retina photoreceptors. However, little is known about the events that trigger the death of RPE cells at the subcellular level. Two-photon excited autofluorescence (TPEF) imaging of RPE cells proves to be well suited to investigate both the morphological and the spectral characteristics of the human RPE cells. The dominant fluorophores of autofluorescence derive from lipofuscin (LF) granules that accumulate in the cytoplasm of the RPE cells with increasing age. Spectral TPEF imaging reveals the existence of abnormal LF granules with blue shifted autofluorescence in RPE cells of aging patients and brings new insights into the complicated composition of the LF granules. Based on a proposed two-photon laser scanning ophthalmoscope, TPEF imaging of the living retina may be valuable for diagnostic and pathological studies of age related eye diseases.

Resonantly Enhanced Axion-Photon Regeneration

CERN Document Server

Sikivie, P; Van Bibber, K; Bibber, Karl van

2007-01-01

We point out that photon regeneration-experiments that search for the axion, or axion-like particles, may be resonantly enhanced by employing matched Fabry-Perot optical cavities encompassing both the axion production and conversion magnetic field regions. Compared to a simple photon regeneration experiment, which uses the laser in a single-pass geometry, this technique can result in a gain in rate of order ${\\cal F}^2$, where ${\\cal F}$ is the finesse of the cavities. This gain could feasibly be $10^{(10-12)}$, corresponding to an improvement in sensitivity in the axion-photon coupling, $g_{a\\gamma\\gamma}$ , of order ${\\cal F}^{1/2} \\sim 10^{(2.5-3)}$, permitting a practical purely laboratory search to probe axion-photon couplings not previously excluded by stellar evolution limits, or solar axion searches.

Selective two-photon excitation of a vibronic state by correlated photons.

Science.gov (United States)

Oka, Hisaki

2011-03-28

We theoretically investigate the two-photon excitation of a molecular vibronic state by correlated photons with energy anticorrelation. A Morse oscillator having three sets of vibronic states is used, as an example, to evaluate the selectivity and efficiency of two-photon excitation. We show that a vibrational mode can be selectively excited with high efficiency by the correlated photons, without phase manipulation or pulse-shaping techniques. This can be achieved by controlling the quantum correlation so that the photon pair concurrently has two pulse widths, namely, a temporally narrow width and a spectrally narrow width. Though this concurrence is seemingly contradictory, we can create such a photon pair by tailoring the quantum correlation between two photons.

Permanently enhanced dynamic triggering probabilities as evidenced by two M ≥ 7.5 earthquakes

Science.gov (United States)

Gomberg, Joan S.

2013-01-01

The 2012 M7.7 Haida Gwaii earthquake radiated waves that likely dynamically triggered the 2013M7.5 Craig earthquake, setting two precedents. First, the triggered earthquake is the largest dynamically triggered shear failure event documented to date. Second, the events highlight a connection between geologic structure, sedimentary troughs that act as waveguides, and triggering probability. The Haida Gwaii earthquake excited extraordinarily large waves within and beyond the Queen Charlotte Trough, which propagated well into mainland Alaska and likely triggering the Craig earthquake along the way. Previously, focusing and associated dynamic triggering have been attributed to unpredictable source effects. This case suggests that elevated dynamic triggering probabilities may exist along the many structures where sedimentary troughs overlie major faults, such as subduction zones’ accretionary prisms and transform faults’ axial valleys. Although data are sparse, I find no evidence of accelerating seismic activity in the vicinity of the Craig rupture between it and the Haida Gwaii earthquake.

Engineering photonic and plasmonic light emission enhancement

Science.gov (United States)

Lawrence, Nathaniel

Semiconductor photonic devices are a rapidly maturing technology which currently occupy multi-billion dollar markets in the areas of LED lighting and optical data communication. LEDs currently demonstrate the highest luminous efficiency of any light source for general lighting. Long-haul optical data communication currently forms the backbone of the global communication network. Proper design of light management is required for photonic devices, which can increase the overall efficiency or add new device functionality. In this thesis, novel methods for the control of light propagation and confinement are developed for the use in integrated photonic devices. The first part of this work focuses on the engineering of field confinement within deep subwavelength plasmonic resonators for the enhancement of light-matter interaction. In this section, plasmonic ring nanocavities are shown to form gap plasmon modes confined to the dielectric region between two metal layers. The scattering properties, near-field enhancement and photonic density of states of nanocavity devices are studied using analytic theory and 3D finite difference time domain simulations. Plasmonic ring nanocavities are fabricated and characterized using photoluminescence intensity and decay rate measurements. A 25 times increase in the radiative decay rate of Er:Si02 is demonstrated in nanocavities where light is confined to volumes as small as 0.01( ln )3. The potential to achieve lasing, due to the enhancement of stimulated emission rate in ring nanocavities, is studied as a route to Si-compatible plasmon-enhanced nanolasers. The second part of this work focuses on the manipulation of light generated in planar semiconductor devices using arrays of dielectric nanopillars. In particular, aperiodic arrays of nanopillars are engineered for omnidirectional light extraction enhancement. Arrays of Er:SiNx, nanopillars are fabricated and a ten times increase in light extraction is experimentally demonstrated

Two-dimensional 'photon fluid': effective photon-photon interaction and physical realizations

International Nuclear Information System (INIS)

Chiao, R Y; Hansson, T H; Leinaas, J M; Viefers, S

2004-01-01

We describe a recently developed effective theory for atom-mediated photon-photon interactions in a two-dimensional 'photon fluid' confined to a Fabry-Perot resonator. The photons in the lowest longitudinal cavity mode will appear as massive bosons interacting via a renormalized delta-function potential with a strength determined by physical parameters such as the density of atoms and the detuning of the photons relative to the resonance frequency of the atoms. We discuss novel quantum phenomena for photons, such as Bose-Einstein condensation and bound state formation, as well as possible experimental scenarios based on Rydberg atoms in a microwave cavity, or alkali atoms in an optical cavity

Two-Color Single-Photon Photoinitiation and Photoinhibition for Subdiffraction Photolithography

Science.gov (United States)

Scott, Timothy F.; Kowalski, Benjamin A.; Sullivan, Amy C.; Bowman, Christopher N.; McLeod, Robert R.

2009-05-01

Controlling and reducing the developed region initiated by photoexposure is one of the fundamental goals of optical lithography. Here, we demonstrate a two-color irradiation scheme whereby initiating species are generated by single-photon absorption at one wavelength while inhibiting species are generated by single-photon absorption at a second, independent wavelength. Co-irradiation at the second wavelength thus reduces the polymerization rate, delaying gelation of the material and facilitating enhanced spatial control over the polymerization. Appropriate overlapping of the two beams produces structures with both feature sizes and monomer conversions otherwise unobtainable with use of single- or two-photon absorption photopolymerization. Additionally, the generated inhibiting species rapidly recombine when irradiation with the second wavelength ceases, allowing for fast sequential exposures not limited by memory effects in the material and thus enabling fabrication of complex two- or three-dimensional structures.

Two-photon induced fluorescence of Cy5-DNA in buffer solution and on silver island films

International Nuclear Information System (INIS)

Lukomska, Joanna; Gryczynski, Ignacy; Malicka, Joanna; Makowiec, Slawomir; Lakowicz, Joseph R.; Gryczynski, Zygmunt

2005-01-01

We report the observation of a strong two-photon induced fluorescence emission of Cy5-DNA within the tunable range of a Ti:Sapphire laser. The estimated two-photon cross-section for Cy5-DNA of 400 GM is about 3.5-fold higher than it was reported for rhodamine B. The fundamental anisotropies of Cy5-DNA are close to the theoretical limits of 2/5 and 4/7 for one- and two-photon excitation, respectively. We also observed an enhanced two-photon induced fluorescence (TPIF) of Cy5-DNA deposited on silver island films (SIFs). In the presence of SIFs, the TPIF is about 100-fold brighter. The brightness increase of Cy5-DNA TPIF near SIFs is mostly due to enhanced local field

Dynamic characterization of hydrophobic and hydrophilic solutes in oleic-acid enhanced transdermal delivery using two-photon fluorescence microscopy

Energy Technology Data Exchange (ETDEWEB)

Tseng, Te-Yu; Yang, Chiu-Sheng; Chen, Yang-Fang [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Tsai, Tsung-Hua [Department of Dermatology, Far Eastern Memorial Hospital, New Taipei City, Taiwan (China); Dong, Chen-Yuan, E-mail: cydong@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Center for Quantum Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Center for Optoelectronic Biomedicine, National Taiwan University, Taipei, Taiwan (China)

2014-10-20

In this letter, we propose an efficient methodology of investigating dynamic properties of sulforhodamine B and rhodamine B hexyl ester molecules transporting across ex-vivo human stratum corneum with and without oleic acid enhancement. Three-dimensional, time-lapse fluorescence images of the stratum corneum can be obtained using two-photon fluorescence microscopy. Furthermore, temporal quantifications of transport enhancements in diffusion parameters can be achieved with the use of Fick's second law. Dynamic characterization of solutes transporting across the stratum corneum is an effective method for understanding transient phenomena in transdermal delivery of probe molecules, leading to improved delivery strategies of molecular species for therapeutic purposes.

Two-photon interference : spatial aspects of two-photon entanglement, diffraction, and scattering

NARCIS (Netherlands)

Peeters, Wouter Herman

2010-01-01

This dissertation contains scientific research within the realm of quantum optics, which is a branch of physics. An experimental and theoretical study is made of two-photon interference phenomena in various optical systems. Spatially entangled photon pairs are produced via the nonlinear optical

Two-photon excitation of argon

International Nuclear Information System (INIS)

Pindzola, P.S.; Payne, M.C.

1982-01-01

The authors calculate two photon excitation parameters for various excited states of argon assuming the absorption of near resonance broad-bandwidth laser radiation. Results are given for the case of two photons absorbed for the same laser beam as well as the case of absorbing photons of different frequency from each of two laser beams. The authors use multiconfiguration Hartree-Fock wave functions to evaluate the second-order sums over matrix elements. Various experimental laser schemes are suggested for the efficient excitation and subsequent ionization of argon

Picosecond phase conjugation in two-photon absorption in poly-di-acetylenes

International Nuclear Information System (INIS)

Nunzi, Dominique Jean-Michel

1990-01-01

Poly-di-acetylenes exhibit a large two-photon absorption at 1064 nm wavelength. Its different effects on phase-conjugate nonlinearity are described in the framework of picosecond experiments. In solutions, gels, and films (optically thin media), third-order susceptibility appears as an increasing intensity dependent function. Phase measurements by nonlinear interferometry with the substrate or with the solvent are compared with predictions of a resonantly driven three level system. Phase-conjugate response exhibits a multi-exponential decay. Polarization symmetries analysis shows a one-dimensional effect. Study under strong static electric field action reveals that we face charged species bound to photoconductive polymer chains. In PTS single crystals (optically thick media), response saturates and cancels at high light intensity. This is well accounted for by propagation equations solved in large two-photon absorption conditions. The effect is exploited in a phase conjugation experiment under external optical pump excitation. We thus demonstrate that enhanced nonlinearity is a two-photon absorption relayed and amplified by mid-gap absorbing species which have been created by this two-photon absorption. We formally face a four-photon absorption described by a positive imaginary seventh-order non-linearity. (author) [fr

Resonant optical tunneling-induced enhancement of the photonic spin Hall effect

Science.gov (United States)

Jiang, Xing; Wang, Qingkai; Guo, Jun; Zhang, Jin; Chen, Shuqing; Dai, Xiaoyu; Xiang, Yuanjiang

2018-04-01

Due to the quantum analogy with optics, the resonant optical tunneling effect (ROTE) has been proposed to investigate both the fundamental physics and the practical applications of optical switches and liquid refractive index sensors. In this paper, the ROTE is used to enhance the spin Hall effect (SHE) of transmitted light. It is demonstrated that sandwiching a layer of a high-refractive-index medium (boron nitride crystal) between two low-refractive-index layers (silica) can effectively enhance the photonic SHE due to the increased refractive index gradient and an enhanced evanescent field near the interface between silica and boron nitride. A maximum transverse shift of the horizontal polarization state in the ROTE structure of about 22.25 µm has been obtained, which is at least three orders of magnitude greater than the transverse shift in the frustrated total internal reflection structure. Moreover, the SHE can be manipulated by controlling the component materials and the thickness of the ROTE structure. These findings open the possibility for future applications of photonic SHE in precision metrology and spin-based photonics.

Data reading with the aid of one-photon and two-photon luminescence in three-dimensional optical memory devices based on photochromic materials

International Nuclear Information System (INIS)

Akimov, Denis A; Zheltikov, Aleksei M; Koroteev, Nikolai I; Naumov, A N; Fedotov, Andrei B; Magnitskiy, Sergey A; Sidorov-Biryukov, D A; Sokolyuk, N T

1998-01-01

The problem of nondestructive reading of the data stored in the interior of a photochromic sample was analysed. A comparison was made of the feasibility of reading based on one-photon and two-photon luminescence. A model was proposed for the processes of reading the data stored in photochromic molecules with the aid of one-photon and two-photon luminescence. In addition to photochromic transitions, account was taken of the transfer of populations between optically coupled transitions in molecules under the action of the exciting radiation. This model provided a satisfactory description of the kinetics of decay of the coloured form of bulk samples of spiropyran and made it possible to determine experimentally the quantum yield of the reverse photoreaction as well as the two-photon absorption cross section of the coloured form. Measurements were made of the characteristic erasure times of the data stored in a photochromic medium under one-photon and two-photon luminescence reading conditions. It was found that the use of two-photon luminescence made it possible to enhance considerably the contrast and localisation of the optical data reading scheme in three-dimensional optical memory devices. The experimental results were used to estimate the two-photon absorption cross section of the coloured form of a sample of indoline spiropyran in a polymethyl methacrylate matrix. (laser applications and other topics in quantum electronics)

Holographic Two-Photon Induced Photopolymerization

Data.gov (United States)

Federal Laboratory Consortium — Holographic two-photon-induced photopolymerization (HTPIP) offers distinct advantages over conventional one-photon-induced photopolymerization and current techniques...

A review of two photon physics

International Nuclear Information System (INIS)

Cooper, S.

1982-08-01

This talk is intended as an introduction for those not yet expert in two-photon physics, especially those e + e - one-photon physicists who still think of two-photon events as background. I concentrate on the physics questions involved, especially emphasizing the areas where I feel progress can be made in the near future, and of necessity leaving most experimental details to be found in the references. After a quick survey of the field and a few words about kinematics, I discuss in detail two major fields: the photon structure function and resonance production. (orig.)

Jet-like correlations with direct-photon and neutral-pion triggers at √{sNN} = 200 GeV

Science.gov (United States)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderson, D. M.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, X.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, Y.; Li, C.; Li, W.; Li, X.; Lin, T.; Lisa, M. A.; Liu, F.; Liu, Y.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Luo, S.; Ma, G. L.; Ma, L.; Ma, Y. G.; Ma, R.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, Z.; Sun, X. M.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, H.; Wang, F.; Wang, Y.; Wang, J. S.; Wang, G.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, N.; Xu, Q. H.; Xu, Z.; Xu, J.; Xu, H.; Xu, Y. F.; Yang, S.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2016-09-01

Azimuthal correlations of charged hadrons with direct-photon (γdir) and neutral-pion (π0) trigger particles are analyzed in central Au+Au and minimum-bias p + p collisions at √{sNN} = 200 GeV in the STAR experiment. The charged-hadron per-trigger yields at mid-rapidity from central Au+Au collisions are compared with p + p collisions to quantify the suppression in Au+Au collisions. The suppression of the away-side associated-particle yields per γdir trigger is independent of the transverse momentum of the trigger particle (pTtrig), whereas the suppression is smaller at low transverse momentum of the associated charged hadrons (pTassoc). Within uncertainty, similar levels of suppression are observed for γdir and π0 triggers as a function of zT (≡ pTassoc/pTtrig). The results are compared with energy-loss-inspired theoretical model predictions. Our studies support previous conclusions that the lost energy reappears predominantly at low transverse momentum, regardless of the trigger energy.

Enhanced Gain in Photonic Crystal Amplifiers

DEFF Research Database (Denmark)

Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann

2012-01-01

We experimentally demonstrate enhanced gain in the slow-light regime of quantum well photonic crystal amplifiers. A strong gain enhancement is observed with the increase of the group refractive index, due to light slow-down. The slow light enhancement is shown in a amplified spontaneous emission....... These results are promising for short and efficient semiconductor optical amplifiers. This effect will also benefit other devices, such as mode locked lasers....

TWO-PHOTON PHYSICS IN NUCLEUS-NUCLEUS COLLISIONS AT RHIC

International Nuclear Information System (INIS)

Nystrand, J.; Klein, S.

1998-01-01

Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z 2 up to an energy of ∼ 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented

Two-photon physics in nucleus-nucleus collisions at RHIC

International Nuclear Information System (INIS)

Nystrand, J.; Klein, S.

1998-01-01

Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z 2 up to an energy of ∼ 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented

Ultra-Low Power Optical Transistor Using a Single Quantum Dot Embedded in a Photonic Wire

DEFF Research Database (Denmark)

Nguyen, H.A.; Grange, T.; Malik, N.S.

2017-01-01

Using a single InAs quantum dot embedded in a GaAs photonic wire, we realize a giant non-linearity between two optical modes to experimentally demonstrate an all-optical transistor triggered by 10 photons.......Using a single InAs quantum dot embedded in a GaAs photonic wire, we realize a giant non-linearity between two optical modes to experimentally demonstrate an all-optical transistor triggered by 10 photons....

Two-photon superradiance in extended medium

International Nuclear Information System (INIS)

Branzan, V.; Enache, N.

1993-01-01

The possibility of collectivization of an ensemble of atoms of an extended system (the distance between atoms is larger or equal to the wave-length of a spontaneous emitted radiation) during two-photon spontaneous decay is theoretically investigated. It is demonstrated that such systems of inverted atoms should emit phase-correlated pairs of photons. The time-space correlation among atoms is realized due to the two-photon exchanging through the electromagnetic field's vacuum. An increase of the spontaneous decay rate of the two-atom inverted ensemble is demonstrated. The dependence of two-photon superradiance on the sample geometry is investigated. A non-equilibrium method of the elimination of the atoms level Fermi-operators is proposed. (Author)

Resonance Enhanced Multi-photon Spectroscopy of DNA

Science.gov (United States)

Ligare, Marshall Robert

For over 50 years DNA has been studied to better understand its connection to life and evolution. These past experiments have led to our understanding of its structure and function in the biological environment but the interaction of DNA with UV radiation at the molecular level is still not very well understood. Unique mechanisms in nucleobase chromaphores protect us from adverse chemical reactions after UV absorption. Studying these processes can help develop theories for prebiotic chemistry and the possibility of alternative forms of DNA. Using resonance enhanced multi-photon spectroscopic techniques in the gas phase allow for the structure and dynamics of individual nucleobases to be studied in detail. Experiments studying different levels of structure/complexity with relation to their biological function are presented. Resonant IR multiphoton dissociation spectroscopy in conjunction with molecular mechanics and DFT calculations are used to determine gas phase structures of anionic nucleotide clusters. A comparison of the identified structures with known biological function shows how the hydrogen bonding of the nucleotides and their clusters free of solvent create favorable structures for quick incorporation into enzymes such as DNA polymerase. Resonance enhanced multi-photon ionization (REMPI) spectroscopy techniques such as resonant two photon ionization (R2PI) and IR-UV double resonance are used to further elucidate the structure and excited state dynamics of the bare nucleobases thymine and uracil. Both exhibit long lived excited electronic states that have been implicated in DNA photolesions which can ultimately lead to melanoma and carcinoma. Our experimental data in comparison with many quantum chemical calculations suggest a new picture for the dynamics of thymine and uracil in the gas phase. A high probability of UV absorption from a vibrationally hot ground state to the excited electronic state shows that the stability of thymine and uracil comes from

Electrons and photons at High Level Trigger in CMS for Run II

CERN Document Server

Bin Anuar, Afiq Aizuddin

2015-01-01

The CMS experiment has been designed with a 2-level trigger system. The first level is implemented using custom-designed electronics. The second level is the so-called High Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm. For Run II of the Large Hadron Collider, the increase in center-of-mass energy and luminosity will raise the event rate to a level challenging for the HLT algorithms. New approaches have been studied to keep the HLT output rate manageable while maintaining thresholds low enough to cover physics analyses. The strategy mainly relies on porting online the ingredients that have been successfully applied in the offline reconstruction, thus allowing to move HLT selection closer to offline cuts. Improvements in HLT electron and photon definitions will be presented, focusing in particular on updated clustering algorithm and the energy calibration procedure, new Particle-Flow-based isolation approach and pileup mitigation techniques, a...

Two Photon Distribution Amplitudes

International Nuclear Information System (INIS)

El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

2008-01-01

The factorization of the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region is demonstrated at the Born order and in the leading logarithmic approximation. The leading order two photon (generalized) distribution amplitudes exhibit a characteristic ln Q 2 behaviour and obey new inhomogeneous evolution equations

Thermodynamics of photon-enhanced thermionic emission solar cells

DEFF Research Database (Denmark)

Reck, Kasper; Hansen, Ole

2014-01-01

Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE...

Thrust distribution of two-jet like events at a photon-photon collider

International Nuclear Information System (INIS)

Kanakubo, Fumiko

1995-01-01

One of the advantages of using a photon-photon collision with the same helicity is that the continuum qq-bar production is suppressed at the lowest order (α s 0 ). However, the helicity suppression does not take place for the gluon radiation process, and qq-barg can be two-jet like. We evaluate the cross sections of the two-jet like events in a photon-photon collision, and present the thrust distributions. We take into account the QCD effect to all orders in α s in the leading-double-log approximation, and show the suppression due to this effect. The evaluation with the energy and the polarization distributions of the photon suggests that the contaminating photons with the opposite helicity contribute dominantly to the two-jet like process. (author)

Real-Time Fluorescence Detection in Aqueous Systems by Combined and Enhanced Photonic and Surface Effects in Patterned Hollow Sphere Colloidal Photonic Crystals.

Science.gov (United States)

Zhong, Kuo; Wang, Ling; Li, Jiaqi; Van Cleuvenbergen, Stijn; Bartic, Carmen; Song, Kai; Clays, Koen

2017-05-16

Hollow sphere colloidal photonic crystals (HSCPCs) exhibit the ability to maintain a high refractive index contrast after infiltration of water, leading to extremely high-quality photonic band gap effects, even in an aqueous (physiological) environment. Superhydrophilic pinning centers in a superhydrophobic environment can be used to strongly confine and concentrate water-soluble analytes. We report a strategy to realize real-time ultrasensitive fluorescence detection in patterned HSCPCs based on strongly enhanced fluorescence due to the photonic band-edge effect combined with wettability differentiation in the superhydrophobic/superhydrophilic pattern. The orthogonal nature of the two strategies allows for a multiplicative effect, resulting in an increase of two orders of magnitude in fluorescence.

Two-photon processes in highly charged ions

International Nuclear Information System (INIS)

Jahrsetz, Thorsten

2015-01-01

Two-photon processes are atomic processes in which an atom interacts simultaneously with two photons. Such processes describe a wide range of phenomena, such as two-photon decay and elastic or inelastic scattering of photons. In recent years two-photon processes involving highly charged heavy ions have become an active area of research. Such studies do not only consider the total transition or scattering rates but also their angular and polarization dependence. To support such examinations in this thesis I present a theoretical framework to describe these properties in all two-photon processes with bound initial and final states and involving heavy H-like or He-like ions. I demonstrate how this framework can be used in some detailed studies of different two-photon processes. Specifically a detailed analysis of two-photon decay of H-like and He-like ions in strong external electromagnetic fields shows the importance of considering the effect of such fields for the physics of such systems. Furthermore I studied the elastic Rayleigh as well as inelastic Raman scattering by heavy H-like ions. I found a number of previously unobserved phenomena in the angular and polarization dependence of the scattering cross-sections that do not only allow to study interesting details of the electronic structure of the ion but might also be useful for the measurement of weak physical effects in such systems.

Two-photon processes in highly charged ions

Energy Technology Data Exchange (ETDEWEB)

Jahrsetz, Thorsten

2015-03-05

Two-photon processes are atomic processes in which an atom interacts simultaneously with two photons. Such processes describe a wide range of phenomena, such as two-photon decay and elastic or inelastic scattering of photons. In recent years two-photon processes involving highly charged heavy ions have become an active area of research. Such studies do not only consider the total transition or scattering rates but also their angular and polarization dependence. To support such examinations in this thesis I present a theoretical framework to describe these properties in all two-photon processes with bound initial and final states and involving heavy H-like or He-like ions. I demonstrate how this framework can be used in some detailed studies of different two-photon processes. Specifically a detailed analysis of two-photon decay of H-like and He-like ions in strong external electromagnetic fields shows the importance of considering the effect of such fields for the physics of such systems. Furthermore I studied the elastic Rayleigh as well as inelastic Raman scattering by heavy H-like ions. I found a number of previously unobserved phenomena in the angular and polarization dependence of the scattering cross-sections that do not only allow to study interesting details of the electronic structure of the ion but might also be useful for the measurement of weak physical effects in such systems.

Jet-like correlations with direct-photon and neutral-pion triggers at sNN=200 GeV

Directory of Open Access Journals (Sweden)

L. Adamczyk

2016-09-01

Full Text Available Azimuthal correlations of charged hadrons with direct-photon (γdir and neutral-pion (π0 trigger particles are analyzed in central Au+Au and minimum-bias p+p collisions at sNN=200 GeV in the STAR experiment. The charged-hadron per-trigger yields at mid-rapidity from central Au+Au collisions are compared with p+p collisions to quantify the suppression in Au+Au collisions. The suppression of the away-side associated-particle yields per γdir trigger is independent of the transverse momentum of the trigger particle (pTtrig, whereas the suppression is smaller at low transverse momentum of the associated charged hadrons (pTassoc. Within uncertainty, similar levels of suppression are observed for γdir and π0 triggers as a function of zT (≡pTassoc/pTtrig. The results are compared with energy-loss-inspired theoretical model predictions. Our studies support previous conclusions that the lost energy reappears predominantly at low transverse momentum, regardless of the trigger energy.

Two-photon stimulated emission and pulse amplification

International Nuclear Information System (INIS)

Yuen, H.P.

1975-01-01

Threshold conditions are given for the sustained operation of standing-wave and long-pulse traveling-wave two-photon lasers. Pulse shortening in long-pulse two-photon amplification, a behavior absent in the one-photon case, is also demonstrated analytically. (U.S.)

Slow-light enhanced optical detection in liquid-infiltrated photonic crystals

DEFF Research Database (Denmark)

Pedersen, Martin Erland Vestergaard; Rishøj, Lars Søgaard; Steffensen, Henrik

2007-01-01

Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner–Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy...... residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light–matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving...

Ratiometric two-photon excited photoluminescence of quantum dots triggered by near-infrared-light for real-time detection of nitric oxide release in situ

International Nuclear Information System (INIS)

Jin, Hui; Gui, Rijun; Sun, Jie; Wang, Yanfeng

2016-01-01

Probe-donor integrated nanocomposites were developed from conjugating silica-coated Mn"2"+:ZnS quantum dots (QDs) with MoS_2 QDs and photosensitive nitric oxide (NO) donors (Fe_4S_3(NO)_7"−, RBS). Under excitation with near-infrared (NIR) light at 808 nm, the Mn"2"+:ZnS@SiO_2/MoS_2-RBS nanocomposites showed the dual-emissive two-photon excited photoluminescence (TPEPL) that induced RBS photolysis to release NO in situ. NO caused TPEPL quenching of Mn"2"+:ZnS QDs, but it produced almost no impact on the TPEPL of MoS_2 QDs. Hence, the nanocomposites were developed as a novel QDs-based ratiometric TPEPL probe for real-time detection of NO release in situ. The ratiometric TPEPL intensity is nearly linear (R"2 = 0.9901) with NO concentration in the range of 0.01∼0.8 μM, which corresponds to the range of NO release time (0∼15 min). The detection limit was calculated to be approximately 4 nM of NO. Experimental results confirmed that this novel ratiometric TPEPL probe possessed high selectivity and sensitivity for the detection of NO against potential competitors, and especially showed high detection performance for NIR-light triggered NO release in tumor intracellular microenvironments. These results would promote the development of versatile probe-donor integrated systems, also providing a facile and efficient strategy to real-time detect the highly controllable drug release in situ, especially in physiological microenvironments. - Highlights: • Mn"2"+:ZnS@SiO_2/MoS_2-RBS nanocomposites were developed as a novel ratiometric two-photon excited fluorescence probe. • This probe could conduct real-time detection of nitric oxide release in situ. • High feasibility of this probe was confirmed in tumor intracellular microenvironments.

Review of Two-Photon Interactions

International Nuclear Information System (INIS)

Urner, David

2004-01-01

Presented are recent results of two-photon interactions. Topics include photon structure functions, inclusive hadron production, differential cross sections derived from tagged γγ fusion events and results in exclusive hadron production, particularly the observations of the η'c

Di-photon cross section measurement and Higgs sensitivity study in the two-photon final state with the ATLAS detector

CERN Document Server

Yuan, Li

2011-01-01

This work is done with the ATLAS collaboration. Three independent methods are proposed to measure the photon trigger efficiency. They are first evaluated using Monte Carlo simulation and then applied on 2010 data. The two photon-based methods show consistent results, with efficiency discrepancy at a few % level. For the method based on electron sample, the statistics is too low to draw conclusion. A detailed QCD di-photon cross-section measurement is performed on a data sample corresponding to a luminosity of 37.2 ±1.2 pb−1, in which a 2D fit method is introduced to extract the signal yields. The differential distributions of the observables Mγγ , pT γγ and Δϕγγ are derived and compared with the predictions from the DIPHOX and RESBOS generators. A good agreement is found for the Mγγ distribution, whereas discrepancies are observed in the pT γγ and Δϕγγ distributions. In the study of the H → γγ channel based on a simulated sample, a deterioration of 4% in the exclusion limit is observed ...

On the enhancement of the back-to-back two-electron-one photon ionization in molecules

Science.gov (United States)

Amusia, Miron; Drukarev, Eugene

2014-05-01

Recently, the long ago predicted quasi-free mechanism of two-electron photoionization was detected already at relatively low energy photoionization in He. It was observed that some pairs of electrons are leaving the target atom back-to-back, i.e. in opposite direction with almost the same energy. They have opposite spin directions. The cross-section of this process depends upon the probability for a pair of electrons to be close to each other before meeting the incoming photon. Such probability is greatly enhanced in molecules with covalent bonding, like H2. In this and similar molecules the electrons spend an essential part of time being between nuclei and thus screening them from each other. We demonstrate that indeed the back-to-back contribution is much bigger in H2 than in He. We analyze qualitatively some other situations that lead to relative growth of back-to-back contribution. Atoms with electrons with bigger principal quantum numbers have bigger back-to-back contributions. An external pressure applied to molecules forces electrons to be closer to each other. As a result for them the back-to-back contribution can be controllable enhanced.

Porous Porphyrin-Based Organosilica Nanoparticles for NIR Two-Photon Photodynamic Therapy and Gene Delivery in Zebrafish

KAUST Repository

Mauriello Jimenez, Chiara

2018-03-30

Periodic mesoporous organosilica nanoparticles emerge as promising vectors for nanomedicine applications. Their properties are very different from those of well-known mesoporous silica nanoparticles as there is no silica source for their synthesis. So far, they have only been synthesized from small bis-silylated organic precursors. However, no studies employing large stimuli-responsive precursors have been reported on such hybrid systems yet. Here, the synthesis of porphyrin-based organosilica nanoparticles from a large octasilylated metalated porphyrin precursor is described for applications in near-infrared two-photon-triggered spatiotemporal theranostics. The nanoparticles display unique interconnected large cavities of 10-80 nm. The framework of the nanoparticles is constituted with J-aggregates of porphyrins, which endows them with two-photon sensitivity. The nanoparticle efficiency for intracellular tracking is first demonstrated by the in vitro near-infrared imaging of breast cancer cells. After functionalization of the nanoparticles with aminopropyltriethoxysilane, two-photon-excited photodynamic therapy in zebrafish is successfully achieved. Two-photon photochemical internalization in cancer cells of the nanoparticles loaded with siRNA is also performed for the first time. Furthermore, siRNA targeting green fluorescent protein complexed with the nanoparticles is delivered in vivo in zebrafish embryos, which demonstrates the versatility of the nanovectors for biomedical applications.

Electrically Induced Two-Photon Transparency in Semiconductor Quantum Wells

International Nuclear Information System (INIS)

Hayat, Alex; Nevet, Amir; Orenstein, Meir

2009-01-01

We demonstrate experimentally two-photon transparency, achieved by current injection into a semiconductor quantum-well structure which exhibits two-photon emission. The two-photon induced luminescence is progressively reduced by the injected current, reaching the point of two-photon transparency - a necessary condition for semiconductor two-photon gain and lasing. These results agree with our calculations.

The study of nonlinear two-photon phenomenon in photonic crystals doped with nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Singh, Mahi R [Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7 (Canada)

2007-02-28

A theory of the nonlinear two-photon absorption has been developed in a photonic crystal doped with an ensemble of four-level nanoparticles. We have considered that the nanoparticles are interacting with the photonic crystal. An expression of two-photon absorption has been obtained by using the density matrix method. The effect of the dipole-dipole interaction has also been included in the formulation. Interesting new phenomena have been predicted. For example, it is found that the inhibition of two-photon absorption can be turned on and off when the decay resonance energies of the four-level nanoparticles are moved within the energy band.

Topology optimized gold nanostrips for enhanced near-infrared photon upconversion

DEFF Research Database (Denmark)

Vester-Petersen, Joakim; Christiansen, Rasmus Ellebæk; Julsgaard, Brian

2017-01-01

This letter presents a topology optimization study of metal nanostructures optimized for electric-field enhancement in the infrared spectrum. Coupling of such nanostructures with suitable ions allows for an increased photon-upconversion yield, with one application being an increased solar-cell...... efficiency by exploiting the long-wavelength part of the solar spectrum. In this work, topology optimization is used to design a periodic array of two-dimensional gold nanostrips for electric-field enhancements in a thin film doped with upconverting erbium ions. The infrared absorption band of erbium...

Possibility of producing the event-ready two-photon polarization entangled state with normal photon detectors

International Nuclear Information System (INIS)

Wang Xiangbin

2003-01-01

We propose a scheme to produce the maximally two-photon polarization entangled state with single-photon sources and the passive linear optics devices. In particular, our scheme only requires the normal photon detectors which distinguish the vacuum and non-vacuum Fock number states. A sophisticated photon detector distinguishing between one-photon state and two-photon state is unnecessary in the scheme

Coherent effects on two-photon correlation and directional emission of two two-level atoms

International Nuclear Information System (INIS)

Ooi, C. H. Raymond; Kim, Byung-Gyu; Lee, Hai-Woong

2007-01-01

Sub- and superradiant dynamics of spontaneously decaying atoms are manifestations of collective many-body systems. We study the internal dynamics and the radiation properties of two atoms in free space. Interesting results are obtained when the atoms are separated by less than half a wavelength of the atomic transition, where the dipole-dipole interaction gives rise to new coherent effects, such as (a) coherence between two intermediate collective states, (b) oscillations in the two-photon correlation G (2) , (c) emission of two photons by one atom, and (d) the loss of directional correlation. We compare the population dynamics during the two-photon emission process with the dynamics of single-photon emission in the cases of a Λ and a V scheme. We compute the temporal correlation and angular correlation of two successively emitted photons using the G (2) for different values of atomic separation. We find antibunching when the atomic separation is a quarter wavelength λ/4. Oscillations in the temporal correlation provide a useful feature for measuring subwavelength atomic separation. Strong directional correlation between two emitted photons is found for atomic separation larger than a wavelength. We also compare the directionality of a photon spontaneously emitted by the two atoms prepared in phased-symmetric and phased-antisymmetric entangled states vertical bar ±> k 0 =e ik 0 ·r 1 vertical bar a 1 ,b 2 >±e ik 0 ·r 2 vertical bar b 1 ,a 2 > by a laser pulse with wave vector k 0 . Photon emission is directionally suppressed along k 0 for the phased-antisymmetric state. The directionality ceases for interatomic distances less than λ/2

Two-Dimentional Photonic Crystal Waveguides

DEFF Research Database (Denmark)

Søndergaard, Thomas; Dridi, Kim

1999-01-01

possible a novel class of optical microcavities, whereas line defects make possible a novel class of waveguides. In this paper we will analyze two-dimensional photonic crystal waveguides based on photonic crystals with rods arranged on a triangular and a square lattice using a plane-wave expansion method......In the recent years a new class of periodic high-index contrast dielectric structures, known as photonic bandgap structures, has been discovered. In these structures frequency intervals, known as photonic bandgaps, where propagation of electromagnetic waves is not allowed, exist due to the periodic...... dielectric function. This is analogous to semiconductors, where electronic bandgaps exist due to the periodic arrangement of atoms. As is also the case for semiconductor structures, photonic bandgap structures may become of even greater value when defects are introduced. In particular, point defects make...

An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

International Nuclear Information System (INIS)

Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha; Ropers, Claus

2015-01-01

We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy

Quarkonium two-photon decays in QCD

International Nuclear Information System (INIS)

Dulyan, L.S.; Khodjamirian, A.Yu.; Magakian, A.D.

1989-01-01

The two-photon decay of tensor charmonium χ c2 → 2 γ is calculated with account of gluon condensate effects. The result is in good agreement with experiment. The two-photon width of pseudoscalar b-quarkonium η b → 2 γ is estimated. 19 refs.; 1 fig.; 1 tab

NIR-emitting molecular-based nanoparticles as new two-photon absorbing nanotools for single particle tracking

Science.gov (United States)

Daniel, J.; Godin, A. G.; Clermont, G.; Lounis, B.; Cognet, L.; Blanchard-Desce, M.

2015-07-01

In order to provide a green alternative to QDs for bioimaging purposes and aiming at designing bright nanoparticles combining both large one- and two-photon brightness, a bottom-up route based on the molecular engineering of dedicated red to NIR emitting dyes that spontaneously form fluorescent organic nanoparticles (FONs) has been implemented. These fully organic nanoparticles built from original quadrupolar dyes are prepared using a simple, expeditious and green protocol that yield very small molecular-based nanoparticles (radius ~ 7 nm) suspension in water showing a nice NIR emission (λem=710 nm). These FONs typically have absorption coefficient more than two orders larger than popular NIR-emitting dyes (such as Alexa Fluor 700, Cy5.5 ….) and much larger Stokes shift values (i.e. up to over 5500 cm-1). They also show very large two-photon absorption response in the 800-1050 nm region (up to about 106 GM) of major promise for two-photon excited fluorescence microscopy. Thanks to their brightness and enhanced photostability, these FONs could be imaged as isolated nanoparticles and tracked using wide-field imaging. As such, thanks to their size and composition (absence of heavy metals), they represent highly promising alternatives to NIR-emitting QDs for use in bioimaging and single particle tracking applications. Moreover, efficient FONs coating was achieved by using a polymeric additive built from a long hydrophobic (PPO) and a short hydrophilic (PEO) segment and having a cationic head group able to interact with the highly negative surface of FONs. This electrostatically-driven interaction promotes both photoluminescence and two-photon absorption enhancement leading to an increase of two-photon brightness of about one order of magnitude. This opens the way to wide-field single particle tracking under two-photon excitation

Raman scattering enhancement in photon-plasmon resonance mediated metal-dielectric microcavity

International Nuclear Information System (INIS)

Guddala, Sriram; Narayana Rao, D.; Dwivedi, Vindesh K.; Vijaya Prakash, G.

2013-01-01

Here, we report the photon-plasmon interaction scheme and enhanced field strengths resulted into the amplification of phonon in a novel microcavity. A metal-dielectric microcavity, with unified cavity photonic mode and localized surface plasmon resonances, is visualized by impregnating the gold nanoparticles into the deep see-through nano-sized pores of porous silicon microcavity. The intense optical field strengths resulting from the photon-plasmon interactions are probed by both resonant and non-resonant Raman scattering experiments. Due to photon-plasmon-phonon interaction mechanism, several orders of enhancement in the intensity of scattered Raman Stokes photon (at 500 cm −1 ) are observed. Our metal nanoparticle-microcavity hybrid system shows the potential to improve the sensing figure of merit as well as the applications of plasmonics for optoelectronics, photovoltaics, and related technologies

Two-photon decay in heavy atoms and ions

International Nuclear Information System (INIS)

Mokler, P.H.; Dunford, R.W

2003-08-01

We review the status of and comment on current developments in the field of two-photon decay in atomic physics research. Recent work has focused on two-photon decays in highly-charged ions and two-photon decay of inner-shell vacancies in heavy neutral atoms. We emphasize the importance of measuring the shape of the continuum emission in two-photon decay as a probe of relativistic effects in the strong central fields found in heavy atomic systems. New experimental approaches and their consequences will be discussed. (orig.)

Two-photon quantum interference in a Michelson interferometer

International Nuclear Information System (INIS)

Odate, Satoru; Wang Haibo; Kobayashi, Takayoshi

2005-01-01

We have observed two-photon quantum interference in a Michelson interferometer. For the first time, we experimentally demonstrated two-photon quantum interference patterns, which show the transition from nonsubwavelength interference fringes to the general subwavelength interference. At the same time, a photon bunching effect was also shown by a postselection. The |1, 1> state with a single photon in a mode corresponding to each arm of the interferometer was exclusively postselected by using path difference between two arms

Non-Liouvillean ion injection via resonantly enhanced two-photon ionization

Directory of Open Access Journals (Sweden)

B. A. Knyazev

2004-03-01

Full Text Available The charge-exchange method is now one of the main techniques for ion injection into accelerators and storage rings. The disadvantages of conventional methods, based on the atom or ion stripping in a material target, are emittance growth, energy straggling, and production of ions in many charge states. Recently suggested stripping methods based on direct photoionization require employment of hard-UV lasers, which still do not exist and must obviously be very bulky and expensive. An alternative method, suggested for injection of proton beams, employs excitation of the atom to 3p intermediate state with subsequent Lorentz ionization in a magnetic field gradient. This technique applies rigid requirements to laser characteristic and is not free of growing of the beam divergence. In this paper a variant of the stripping technique based on the resonantly enhanced two-photon ionization (RETPI is considered. The technique allows ionization of singly charged ions of the elements from helium to bismuth. A variant of the technique can be used for proton injection. RETPI can be applied for both ion injection and stacking, as well as for diagnostics of ion beam characteristics on the orbit. Stripping efficiency can be about 100% for the singly charged ions having the singlet ground state and decreases for the other ions. Special methods for “cleaning” unwanted atomic states in such ions, that can provide high stripping efficiency, are discussed. Excimer lasers with very moderate parameters can be employed for implementation of this technique for almost all elements. Numerical examples show that for most of the singly charged ions and for hydrogen atom necessary laser-beam energy density is merely 0.5–8  J/cm^{2} for a 1 m interaction region, and is 10 times higher for several light ions.

Coherence revivals in two-photon frequency combs

International Nuclear Information System (INIS)

Torres-Company, Victor; Lancis, Jesus; Lajunen, Hanna; Friberg, Ari T.

2011-01-01

We describe and theoretically analyze the self-imaging Talbot effect of entangled photon pairs in the time domain. Rich phenomena are observed in coherence propagation along dispersive media of mode-locked two-photon states with frequency entanglement exhibiting a comblike correlation function. Our results can be used to remotely transfer frequency standards through optical fiber networks with two-photon light, avoiding the requirement of dispersion compensation.

Theory of two-photon interactions with broadband down-converted light and entangled photons

International Nuclear Information System (INIS)

Dayan, Barak

2007-01-01

When two-photon interactions are induced by down-converted light with a bandwidth that exceeds the pump bandwidth, they can obtain a behavior that is pulselike temporally, yet spectrally narrow. At low photon fluxes this behavior reflects the time and energy entanglement between the down-converted photons. However, two-photon interactions such as two-photon absorption (TPA) and sum-frequency generation (SFG) can exhibit such a behavior even at high power levels, as long as the final state (i.e., the atomic level in TPA, or the generated light in SFG) is narrow-band enough. This behavior does not depend on the squeezing properties of the light, is insensitive to linear losses, and has potential applications. In this paper we describe analytically this behavior for traveling-wave down conversion with continuous or pulsed pumping, both for high- and low-power regimes. For this we derive a quantum-mechanical expression for the down-converted amplitude generated by an arbitrary pump, and formulate operators that represent various two-photon interactions induced by broadband light. This model is in excellent agreement with experimental results of TPA and SFG with high-power down-converted light and with entangled photons [Dayan et al., Phys. Rev. Lett. 93, 023005 (2004); 94, 043602 (2005); Pe'er et al., ibid. 94, 073601 (2005)

Fundamental limitations to gain enhancement in slow-light photonic structures

DEFF Research Database (Denmark)

Grgic, Jure; Ott, Johan Raunkjar; Wang, Fengwen

2012-01-01

We present a non-perturbative analysis of light-matter interaction in active photonic crystal waveguides in the slow-light regime. Inclusion of gain is shown to modify the underlying dispersion law, thereby degrading the slow-light enhancement.......We present a non-perturbative analysis of light-matter interaction in active photonic crystal waveguides in the slow-light regime. Inclusion of gain is shown to modify the underlying dispersion law, thereby degrading the slow-light enhancement....

Time-resolved statistics of photon pairs in two-cavity Josephson photonics

Energy Technology Data Exchange (ETDEWEB)

Dambach, Simon; Kubala, Bjoern; Ankerhold, Joachim [Institute for Complex Quantum Systems and IQST, Ulm University (Germany)

2017-06-15

We analyze the creation and emission of pairs of highly nonclassical microwave photons in a setup where a voltage-biased Josephson junction is connected in series to two electromagnetic oscillators. Tuning the external voltage such that the Josephson frequency equals the sum of the two mode frequencies, each tunneling Cooper pair creates one additional photon in both of the two oscillators. The time-resolved statistics of photon emission events from the two oscillators is investigated by means of single- and cross-oscillator variants of the second-order correlation function g{sup (2)}(τ) and the waiting-time distribution w(τ). They provide insight into the strongly correlated quantum dynamics of the two oscillator subsystems and reveal a rich variety of quantum features of light including strong antibunching and the presence of negative values in the Wigner function. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Ratiometric two-photon excited photoluminescence of quantum dots triggered by near-infrared-light for real-time detection of nitric oxide release in situ

Energy Technology Data Exchange (ETDEWEB)

Jin, Hui [Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, College of Chemistry and Chemical Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Shandong 266071 (China); Gui, Rijun, E-mail: guirijun@qdu.edu.cn [Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, College of Chemistry and Chemical Engineering, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Shandong 266071 (China); Sun, Jie; Wang, Yanfeng [Institute of Materia Medica, Shandong Academy of Medical Sciences, Jinan 250062 (China)

2016-05-30

Probe-donor integrated nanocomposites were developed from conjugating silica-coated Mn{sup 2+}:ZnS quantum dots (QDs) with MoS{sub 2} QDs and photosensitive nitric oxide (NO) donors (Fe{sub 4}S{sub 3}(NO){sub 7}{sup −}, RBS). Under excitation with near-infrared (NIR) light at 808 nm, the Mn{sup 2+}:ZnS@SiO{sub 2}/MoS{sub 2}-RBS nanocomposites showed the dual-emissive two-photon excited photoluminescence (TPEPL) that induced RBS photolysis to release NO in situ. NO caused TPEPL quenching of Mn{sup 2+}:ZnS QDs, but it produced almost no impact on the TPEPL of MoS{sub 2} QDs. Hence, the nanocomposites were developed as a novel QDs-based ratiometric TPEPL probe for real-time detection of NO release in situ. The ratiometric TPEPL intensity is nearly linear (R{sup 2} = 0.9901) with NO concentration in the range of 0.01∼0.8 μM, which corresponds to the range of NO release time (0∼15 min). The detection limit was calculated to be approximately 4 nM of NO. Experimental results confirmed that this novel ratiometric TPEPL probe possessed high selectivity and sensitivity for the detection of NO against potential competitors, and especially showed high detection performance for NIR-light triggered NO release in tumor intracellular microenvironments. These results would promote the development of versatile probe-donor integrated systems, also providing a facile and efficient strategy to real-time detect the highly controllable drug release in situ, especially in physiological microenvironments. - Highlights: • Mn{sup 2+}:ZnS@SiO{sub 2}/MoS{sub 2}-RBS nanocomposites were developed as a novel ratiometric two-photon excited fluorescence probe. • This probe could conduct real-time detection of nitric oxide release in situ. • High feasibility of this probe was confirmed in tumor intracellular microenvironments.

Photon-number correlation for quantum enhanced imaging and sensing

Science.gov (United States)

Meda, A.; Losero, E.; Samantaray, N.; Scafirimuto, F.; Pradyumna, S.; Avella, A.; Ruo-Berchera, I.; Genovese, M.

2017-09-01

In this review we present the potentialities and the achievements of the use of non-classical photon-number correlations in twin-beam states for many applications, ranging from imaging to metrology. Photon-number correlations in the quantum regime are easily produced and are rather robust against unavoidable experimental losses, and noise in some cases, if compared to the entanglement, where losing one photon can completely compromise the state and its exploitable advantages. Here, we will focus on quantum enhanced protocols in which only phase-insensitive intensity measurements (photon-number counting) are performed, which allow probing the transmission/absorption properties of a system, leading, for example, to innovative target detection schemes in a strong background. In this framework, one of the advantages is that the sources experimentally available emit a wide number of pair-wise correlated modes, which can be intercepted and exploited separately, for example by many pixels of a camera, providing a parallelism, essential in several applications, such as wide-field sub-shot-noise imaging and quantum enhanced ghost imaging. Finally, non-classical correlation enables new possibilities in quantum radiometry, e.g. the possibility of absolute calibration of a spatial resolving detector from the on-off single-photon regime to the linear regime in the same setup.

Photon echo with a few photons in two-level atoms

International Nuclear Information System (INIS)

Bonarota, M; Dajczgewand, J; Louchet-Chauvet, A; Le Gouët, J-L; Chanelière, T

2014-01-01

To store and retrieve signals at the single photon level, various photon echo schemes have resorted to complex preparation steps involving ancillary shelving states in multi-level atoms. For the first time, we experimentally demonstrate photon echo operation at such a low signal intensity without any preparation step, which allows us to work with mere two-level atoms. This simplified approach relies on the so-coined ‘revival of silenced echo’ (ROSE) scheme. Low noise conditions are obtained by returning the atoms to the ground state before the echo emission. In the present paper we manage ROSE in photon counting conditions, showing that very strong control fields can be compatible with extremely weak signals, making ROSE consistent with quantum memory requirements. (paper)

GPU Enhancement of the Trigger to Extend Physics Reach at the LHC

CERN Document Server

Halyo, V; Jindal, P; LeGresley, P; Lujan, P

2013-01-01

Significant new challenges are continuously confronting the High Energy Physics (HEP) experiments, in particular the two detectors at the Large Hadron Collider (LHC) at CERN, where nominal conditions deliver proton-proton collisions to the detectors at a rate of 40 MHz. This rate must be significantly reduced to comply with both the performance limitations of the mass storage hardware and the capabilities of the computing resources to process the collected data in a timely fashion for physics analysis. At the same time, the physics signals of interest must be retained with high efficiency. The quest for rare new physics phenomena at the LHC leads us to evaluate a Graphics Processing Unit (GPU) enhancement of the existing High-Level Trigger (HLT), made possible by the current flexibility of the trigger system, which not only provides faster and more efficient event selection, but also includes the possibility of new complex triggers that were not previously feasible. A new tracking algorithm is evaluated on a ...

Two-Particle Correlations with Neutral Pion and Direct Photon Triggers in pp and Pb+Pb Collisions with ALICE at the LHC

CERN Document Server

Zhu, Xiangrong; Constantinos, Loizides; Zhongbao, Yin; Loizides, Constantinos; Zhongbao, Yin

Two-particle correlations is considered as a powerful probe for understanding the properties of the strongly interacting hot and dense medium. In such an analysis, a particle is chosen from higher $p_{\\rm T}$ region and called the trigger particle, which is presumably from jet fragmentations. The so called associated particles from lower $p_{\\rm T}$ region are always from the other fragmentation of the jet, or another production, such as collective flow. At RHIC and LHC, the measurements of the azimuthal angle distribution from two-particle correlations in A+A collisions show a strong suppression even disappeared at the high $p_{\\rm T}$ and enhancement with double-peak at the low $p_{\\rm T}$ on the away side, and ``ridge'' structure in pseudo-rapidity direction at the low $p_{\\rm T}$ on the near side compared to pp collisions. All the measurements can be explained as the effects of the hot and dense medium, and imply the Quark-Gluon Plasma is indeed formed in the heavy-ion collisions. When the direct ph...

The intensity detection of single-photon detectors based on photon counting probability density statistics

International Nuclear Information System (INIS)

Zhang Zijing; Song Jie; Zhao Yuan; Wu Long

2017-01-01

Single-photon detectors possess the ultra-high sensitivity, but they cannot directly respond to signal intensity. Conventional methods adopt sampling gates with fixed width and count the triggered number of sampling gates, which is capable of obtaining photon counting probability to estimate the echo signal intensity. In this paper, we not only count the number of triggered sampling gates, but also record the triggered time position of photon counting pulses. The photon counting probability density distribution is obtained through the statistics of a series of the triggered time positions. Then Minimum Variance Unbiased Estimation (MVUE) method is used to estimate the echo signal intensity. Compared with conventional methods, this method can improve the estimation accuracy of echo signal intensity due to the acquisition of more detected information. Finally, a proof-of-principle laboratory system is established. The estimation accuracy of echo signal intensity is discussed and a high accuracy intensity image is acquired under low-light level environments. (paper)

Two-Photon Fluorescence Microscope for Microgravity Research

Science.gov (United States)

Fischer, David G.; Zimmerli, Gregory A.; Asipauskas, Marius

2005-01-01

A two-photon fluorescence microscope has been developed for the study of biophysical phenomena. Two-photon microscopy is a novel form of laser-based scanning microscopy that enables three-dimensional imaging without many of the problems inherent in confocal microscopy. Unlike one-photon optical microscopy, two-photon microscopy utilizes the simultaneous nonlinear absorption of two near-infrared photons. However, the efficiency of two-photon absorption is much lower than that of one-photon absorption, so an ultra-fast pulsed laser source is typically employed. On the other hand, the critical energy threshold for two-photon absorption leads to fluorophore excitation that is intrinsically localized to the focal volume. Consequently, two-photon microscopy enables optical sectioning and confocal performance without the need for a signal-limiting pinhole. In addition, there is a reduction (relative to one-photon optical microscopy) in photon-induced damage because of the longer excitation wavelength. This reduction is especially advantageous for in vivo studies. Relative to confocal microscopy, there is also a reduction in background fluorescence, and, because of a reduction in Rayleigh scattering, there is a 4 increase of penetration depth. The prohibitive cost of a commercial two-photon fluorescence-microscope system, as well as a need for modularity, has led to the construction of a custom-built system (see Figure 1). This system includes a coherent mode-locked titanium: sapphire laser emitting 120-fs-duration pulses at a repetition rate of 80 MHz. The pulsed laser has an average output power of 800 mW and a wavelength tuning range of 700 to 980 nm, enabling the excitation of a variety of targeted fluorophores. The output from the laser is attenuated, spatially filtered, and then directed into a confocal scanning head that has been modified to provide for side entry of the laser beam. The laser output coupler has been replaced with a dichroic filter that reflects the

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue.

Science.gov (United States)

Sakadzić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A

2010-09-01

Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies.

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

Science.gov (United States)

Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A.; Mandeville, Emiri T.; Srinivasan, Vivek J.; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H.; Vinogradov, Sergei A.; Boas, David A.

2010-01-01

The ability to measure oxygen partial pressure (pO2) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO2 measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here, we report the first practical in vivo two-photon high-resolution pO2 measurements in small rodents’ cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 µm, sub-second temporal resolution and requires low probe concentration. Most importantly, the properties of the probe allowed for the first direct high-resolution measurement of cortical extravascular (tissue) pO2, opening numerous possibilities for functional metabolic brain studies. PMID:20693997

A segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics for a PET scanner

CERN Document Server

Chesi, Enrico Guido; Joram, C; Mathot, S; Séguinot, Jacques; Weilhammer, P; Ciocia, F; De Leo, R; Nappi, E; Vilardi, I; Argentieri, A; Corsi, F; Dragone, A; Pasqua, D

2006-01-01

We describe the design, fabrication and test results of a segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a Positron Emission Tomograph. Emphasis is put on the PET specific features of the device. The detector has been fabricated in the photocathode facility at CERN.

Engineering Photon-Photon Interactions within Rubidium-Filled Waveguides

Science.gov (United States)

Perrella, C.; Light, P. S.; Vahid, S. Afshar; Benabid, F.; Luiten, A. N.

2018-04-01

Strong photon-photon interactions are a required ingredient for deterministic two-photon optical quantum logic gates. Multiphoton transitions in dense atomic vapors have been shown to be a promising avenue for producing such interactions. The strength of a multiphoton interaction can be enhanced by conducting the interaction in highly confined geometries such as small-cross-section optical waveguides. We demonstrate, both experimentally and theoretically, that the strength of such interactions scale only with the optical mode diameter, d , not d2 as might be initially expected. This weakening of the interaction arises from atomic motion inside the waveguides. We create an interaction between two optical signals, at 780 and 776 nm, using the 5 S1 /2→5 D5 /2 two-photon transition in rubidium vapor within a range of hollow-core fibers with different core sizes. The interaction strength is characterized by observing the absorption and phase shift induced on the 780-nm beam, which is in close agreement with theoretical modeling that accounts for the atomic motion inside the fibers. These observations demonstrate that transit-time effects upon multiphoton transitions are of key importance when engineering photon-photon interactions within small-cross-section waveguides that might otherwise be thought to lead to enhanced optical nonlinearity through increased intensities.

Quantum theory of two-photon wavepacket interference in a beamsplitter

International Nuclear Information System (INIS)

Wang, Kaige

2006-01-01

A general theory is derived for the interference of a two-photon wavepacket in a beamsplitter. The theory is presented in the Schroedinger picture so that the quantum nature of the two-photon interference is explicitly revealed. We find that the topological symmetry of the probability-amplitude spectrum of the two-photon wavepacket dominates the nature of the two-photon interference, which may be distinguished by the increase or decrease of the coincidence probability in the absence of interference. However, two-photon entanglement can be identified by the nature of the interference. We demonstrate the necessary and sufficient conditions for perfect two-photon interference. It is shown that a two-photon entangled state with an anti-symmetric spectrum passes through a 50/50 beamsplitter with perfect transparency. The theory provides us with a unified understanding of the various two-photon interference effects. (topical review)

Microsphere imaging with confocal microscopy and two photon microscopy

International Nuclear Information System (INIS)

Chun, Hyung Su; An, Kyung Won; Lee, Jai Hyung

2002-01-01

We have acquired images of polystyrene and fused-silica microsphere by using conventional optical microscopy, confocal microscopy and two-photon microscopy, and performed comparative analysis of these images. Different from conventional optical microscopy, confocal and two-photon microscopy had good optical sectioning capability. In addition, confocal microscopy and two-photon microscopy had better lateral resolution than conventional optical microscopy. These results are attributed to confocality and nonlinearity of confocal microscopy and two photon microscopy, respectively.

On the kinematics of the two-photon Cherenkov effect

International Nuclear Information System (INIS)

Afanas'ev, G.N.; Stepanovskij, Yu.P.

2003-01-01

We study the kinematics of the two-photon Cherenkov effect. In the general case, the emission angles of two photons satisfy certain inequalities and the corresponding radiation intensities are rather diffused. In special cases, when the above inequalities reduce to equalities, the emission angles of two photons are fixed and the corresponding radiation intensities should have sharp maxima at these angles. This makes easier the experimental study of the two-photon Cherenkov effect

Highly selective population of two excited states in nonresonant two-photon absorption

International Nuclear Information System (INIS)

Zhang Hui; Zhang Shi-An; Sun Zhen-Rong

2011-01-01

A nonresonant two-photon absorption process can be manipulated by tailoring the ultra-short laser pulse. In this paper, we theoretically demonstrate a highly selective population of two excited states in the nonresonant two-photon absorption process by rationally designing a spectral phase distribution. Our results show that one excited state is maximally populated while the other state population is widely tunable from zero to the maximum value. We believe that the theoretical results may play an important role in the selective population of a more complex nonlinear process comprising nonresonant two-photon absorption, such as resonance-mediated (2+1)-three-photon absorption and (2+1)-resonant multiphoton ionization. (atomic and molecular physics)

Two-Photon Ghost Image and Interference-Diffraction

Science.gov (United States)

Shih, Y. H.; Sergienko, A. V.; Pittman, T. B.; Strekalov, D. V.; Klyshko, D. N.

1996-01-01

One of the most surprising consequences of quantum mechanics is entanglement of two or more distance particles. The two-particle entangled state was mathematically formulated by Schrodinger. Based on this unusual quantum behavior, EPR defined their 'physical reality' and then asked the question: 'Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?' One may not appreciate EPR's criterion of physical reality and insist that 'no elementary quantum phenomenon is a phenomenon until it is a recorded phenomenon'. Optical spontaneous parametric down conversion (SPDC) is the most effective mechanism to generate an EPR type entangled two-photon state. In SPDC, an optical beam, called the pump, is incident on a birefringent crystal. The pump is intense enough so that nonlinear effects lead to the conversion of pump photons into pairs of photons, historically called signal and idler. Technically, the SPDC is said to be type-1 or type-2, depending on whether the signal and idler beams have parallel or orthogonal polarization. The SPDC conversion efficiency is typically on the order of 10(exp -9) to 10(exp -11), depending on the SPDC nonlinear material. The signal and idler intensities are extremely low, only single photon detection devices can register them. The quantum entanglement nature of SPDC has been demonstrated in EPR-Bohm experiments and Bell's inequality measurements. The following two experiments were recently performed in our laboratory, which are more closely related to the original 1935 EPR gedankenezperiment. The first experiment is a two-photon optical imaging type experiment, which has been named 'ghost image' by the physics community. The signal and idler beams of SPDC are sent in different directions, so that the detection of the signal and idler photons can be performed by two distant photon counting detectors. An aperture object (mask) is placed in front of the signal photon detector and illuminated by the signal beam through a

Squeezing via two-photon transitions

Science.gov (United States)

Savage, C. M.; Walls, D. F.

1986-05-01

The squeezing spectrum for a cavity field mode interacting with an ensemble of three-level 'Lambda-configuration' atoms by an effective two-photon transition is calculated. The advantage of the three-level Lambda system as a squeezing medium, that is, optical nonlinearity without atomic saturation, has recently been pointed out by Reid, Walls, and Dalton. Perfect squeezing is predicted at the turning points for dispersive optical bistability and good squeezing for a range of other cases. Three-level ladder atoms interacting by an effective two-photon transition are also shown to give perfect squeezing in the dispersive limit.

Exclusive hadron production in two photon reactions

International Nuclear Information System (INIS)

Poppe, M.

1986-02-01

This paper summarises experimental results on exclusive hadron production in two photon collisions at electron positron storage rings and attempts some interpretation. Experimental know how is described and new suggestions are made for future analyses. New model calculations on resonance form factors and pair production amplitudes are presented. The two photon vertex is decomposed such that experiments can be parameterised with the minimal number of free parameters. Selection rules for off shell photon collisions are given in addition to Yang's theorems. (orig.)

Two-dimensional topological photonic systems

Science.gov (United States)

Sun, Xiao-Chen; He, Cheng; Liu, Xiao-Ping; Lu, Ming-Hui; Zhu, Shi-Ning; Chen, Yan-Feng

2017-09-01

The topological phase of matter, originally proposed and first demonstrated in fermionic electronic systems, has drawn considerable research attention in the past decades due to its robust transport of edge states and its potential with respect to future quantum information, communication, and computation. Recently, searching for such a unique material phase in bosonic systems has become a hot research topic worldwide. So far, many bosonic topological models and methods for realizing them have been discovered in photonic systems, acoustic systems, mechanical systems, etc. These discoveries have certainly yielded vast opportunities in designing material phases and related properties in the topological domain. In this review, we first focus on some of the representative photonic topological models and employ the underlying Dirac model to analyze the edge states and geometric phase. On the basis of these models, three common types of two-dimensional topological photonic systems are discussed: 1) photonic quantum Hall effect with broken time-reversal symmetry; 2) photonic topological insulator and the associated pseudo-time-reversal symmetry-protected mechanism; 3) time/space periodically modulated photonic Floquet topological insulator. Finally, we provide a summary and extension of this emerging field, including a brief introduction to the Weyl point in three-dimensional systems.

Phonon-assisted two-photon exciton transitions in semiconductors

International Nuclear Information System (INIS)

Hassan, A.R.

1987-08-01

The theory of phonon-assisted two-photon transitions to excitonic states in semiconductors has been theoretically investigated. The effects of both the nonparabolicity of the band and the degeneracy of the valence band have been taken into account. Expressions for the absorption coefficient through different band models are calculated. The numerical applications to CdI 2 and GaP show that the 4-band model gives the dominant contribution which leads to a final s-exciton state. An exciton peak appears at an energy which is close to that recently observed in CdI 2 . The non-parabolic effect enhances the absorption coefficient by a two-order of magnitude. (author). 6 refs, 1 fig., 1 tab

Fluorescence Enhancement on Large Area Self-Assembled Plasmonic-3D Photonic Crystals.

Science.gov (United States)

Chen, Guojian; Wang, Dongzhu; Hong, Wei; Sun, Lu; Zhu, Yongxiang; Chen, Xudong

2017-03-01

Discontinuous plasmonic-3D photonic crystal hybrid structures are fabricated in order to evaluate the coupling effect of surface plasmon resonance and the photonic stop band. The nanostructures are prepared by silver sputtering deposition on top of hydrophobic 3D photonic crystals. The localized surface plasmon resonance of the nanostructure has a symbiotic relationship with the 3D photonic stop band, leading to highly tunable characteristics. Fluorescence enhancements of conjugated polymer and quantum dot based on these hybrid structures are studied. The maximum fluorescence enhancement for the conjugated polymer of poly(5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene) potassium salt by a factor of 87 is achieved as compared with that on a glass substrate due to the enhanced near-field from the discontinuous plasmonic structures, strong scattering effects from rough metal surface with photonic stop band, and accelerated decay rates from metal-coupled excited state of the fluorophore. It is demonstrated that the enhancement induced by the hybrid structures has a larger effective distance (optimum thickness ≈130 nm) than conventional plasmonic systems. It is expected that this approach has tremendous potential in the field of sensors, fluorescence-imaging, and optoelectronic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced complete photonic bandgap in a moderate refractive index contrast chalcogenide-air system with connected-annular-rods photonic crystals

KAUST Repository

Hou, Jin

2018-03-27

Connected-annular-rods photonic crystals (CARPCs) in both triangular and square lattices are proposed to enhance the two-dimensional complete photonic bandgap (CPBG) for chalcogenide material systems with moderate refractive index contrast. For the typical chalcogenide-glass–air system with an index contrast of 2.8:1, the optimized square lattice CARPC exhibits a significantly larger normalized CPBG of about 13.50%, though the use of triangular lattice CARPC is unable to enhance the CPBG. It is almost twice as large as our previously reported result [IEEE J. Sel. Top. Quantum Electron. 22, 4900108 (2016) [CrossRef] ]. Moreover, the CPBG of the square-lattice CARPC could remain until an index contrast as low as 2.24:1. The result not only favors wideband CPBG applications for index contrast systems near 2.8:1, but also makes various optical applications that are dependent on CPBG possible for more widely refractive index contrast systems.

Nano-optical observation of cascade switching in a parallel superconducting nanowire single photon detector

International Nuclear Information System (INIS)

Heath, Robert M.; Tanner, Michael G.; Casaburi, Alessandro; Hadfield, Robert H.; Webster, Mark G.; San Emeterio Alvarez, Lara; Jiang, Weitao; Barber, Zoe H.; Warburton, Richard J.

2014-01-01

The device physics of parallel-wire superconducting nanowire single photon detectors is based on a cascade process. Using nano-optical techniques and a parallel wire device with spatially separate pixels, we explicitly demonstrate the single- and multi-photon triggering regimes. We develop a model for describing efficiency of a detector operating in the arm-trigger regime. We investigate the timing response of the detector when illuminating a single pixel and two pixels. We see a change in the active area of the detector between the two regimes and find the two-pixel trigger regime to have a faster timing response than the one-pixel regime

Electronic trigger for the ASP experiment

International Nuclear Information System (INIS)

Wilson, R.J.

1985-11-01

The Anomalous Single Photon (ASP) electronic trigger is described. The experiments is based on an electromagnetic calorimeter composed of arrays of lead glass blocks, read out with photo-multiplier tubes, surrounding the interaction point at the PEP storage ring. The primary requirement of the trigger system is to be sensitive to low energy (approx. =0.5 GeV and above) photons whilst discriminating against high backgrounds at PEP. Analogue summing of the PMT signals and a sequence of programmable digital look-up tables produces a ''dead-timeless'' trigger for the beam collision rate of 408 kHz. 6 refs., 6 figs

Enhancement of broadband optical absorption in photovoltaic devices by band-edge effect of photonic crystals.

Science.gov (United States)

Tanaka, Yoshinori; Kawamoto, Yosuke; Fujita, Masayuki; Noda, Susumu

2013-08-26

We numerically investigate broadband optical absorption enhancement in thin, 400-nm thick microcrystalline silicon (µc-Si) photovoltaic devices by photonic crystals (PCs). We realize absorption enhancement by coupling the light from the free space to the large area resonant modes at the photonic band-edge induced by the photonic crystals. We show that multiple photonic band-edge modes can be produced by higher order modes in the vertical direction of the Si photovoltaic layer, which can enhance the absorption on multiple wavelengths. Moreover, we reveal that the photonic superlattice structure can produce more photonic band-edge modes that lead to further optical absorption. The absorption average in wavelengths of 500-1000 nm weighted to the solar spectrum (AM 1.5) increases almost twice: from 33% without photonic crystal to 58% with a 4 × 4 period superlattice photonic crystal; our result outperforms the Lambertian textured structure.

Electromagnetically induced two-photon transparency in rubidium atoms

International Nuclear Information System (INIS)

Wang, D.; Gao, J.Y.; Xu, J.H.; Bassani, F.; La Rocca, G.C.; Salerno Univ.

2001-01-01

We present an experimental demonstration of electromagnetically induced two-photon transparency (EITT) in room temperature rubidium vapor. The 8S 1/2 to 5P 1/2 fluorescence is used to monitor the 5S 1/2 (F = 3) to 8S 1/2 (F = 3) two-photon absorption near resonance with the intermediate state 5P 3/2 . A controlling pump laser beam is employed to coherently couple the 5P 3/2 and 5D 5/2 states, thus producing two dressed intermediate states which give rise to destructive interference in the two-photon transition. An induced two-photon transparency of about 80% has been obtained at resonance; our experimental findings are in good agreement with the general theory of Agarwal et al. (1996), when the appropriate spectroscopic parameters are used. (orig.)

Highly efficient photonic nanowire single-photon sources for quantum information applications

DEFF Research Database (Denmark)

Gregersen, Niels; Claudon, J.; Munsch, M.

2013-01-01

to a collection efficiency of only 1-2 %, and efficient light extraction thus poses a major challenge in SPS engineering. Initial efforts to improve the efficiency have exploited cavity quantum electrodynamics (cQED) to efficiently couple the emitted photons to the optical cavity mode. An alternative approach......Within the emerging field of optical quantum information processing, the current challenge is to construct the basic building blocks for the quantum computing and communication systems. A key component is the singlephoton source (SPS) capable of emitting single photons on demand. Ideally, the SPS...... must feature near-unity efficiency, where the efficiency is defined as the number of detected photons per trigger, the probability g(2)(τ=0) of multi-photon emission events should be 0 and the emitted photons are required to be indistinguishable. An optically or electrically triggered quantum light...

Ultrabright narrow-band telecom two-photon source for long-distance quantum communication

Science.gov (United States)

Niizeki, Kazuya; Ikeda, Kohei; Zheng, Mingyang; Xie, Xiuping; Okamura, Kotaro; Takei, Nobuyuki; Namekata, Naoto; Inoue, Shuichiro; Kosaka, Hideo; Horikiri, Tomoyuki

2018-04-01

We demonstrate an ultrabright narrow-band two-photon source at the 1.5 µm telecom wavelength for long-distance quantum communication. By utilizing a bow-tie cavity, we obtain a cavity enhancement factor of 4.06 × 104. Our measurement of the second-order correlation function G (2)(τ) reveals that the linewidth of 2.4 MHz has been hitherto unachieved in the 1.5 µm telecom band. This two-photon source is useful for obtaining a high absorption probability close to unity by quantum memories set inside quantum repeater nodes. Furthermore, to the best of our knowledge, the observed spectral brightness of 3.94 × 105 pairs/(s·MHz·mW) is also the highest reported over all wavelengths.

Enhancement of two photon absorption with Ni doping in the dilute magnetic semiconductor ZnO crystalline nanorods

Energy Technology Data Exchange (ETDEWEB)

Rana, Amit Kumar; Kumar, Yogendra; Arjunan, M.S.; Sen, Somaditya; Shirage, Parasharam M., E-mail: pmshirage@iiti.ac.in, E-mail: paras.shirage@gmail.com [Department of Physics, Indian Institute of Technology Indore, Simrol Campus, Khandwa Road, Indore 452020 (India); Centre of Materials Science and Engineering, Indian Institute of Technology Indore, Simrol Campus, Khandwa Road, Indore 452020 (India); J, Aneesh; Adarsh, K. V. [Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023 (India)

2015-12-07

In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient (β) increases by as much as 14 times, i.e., 7.6 ± 0.4 to 112 ± 6 cm/GW, when the Ni doping is increased from 0% to 10%. The substantial enhancement in β is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UV-Vis and photoluminescence spectroscopies, continuously redshift with increasing Ni doping concentration. We envision that the strong nonlinear optical properties together with their dilute magnetic effects, they form an important class of materials for potential applications in magneto-optical and integrated optical chips.

Enhancement of two photon absorption with Ni doping in the dilute magnetic semiconductor ZnO crystalline nanorods

International Nuclear Information System (INIS)

Rana, Amit Kumar; Kumar, Yogendra; Arjunan, M.S.; Sen, Somaditya; Shirage, Parasharam M.; J, Aneesh; Adarsh, K. V.

2015-01-01

In this letter, we have investigated the third-order optical nonlinearities of high-quality Ni doped ZnO nanorods crystallized in wurtzite lattice, prepared by the wet chemical method. In our experiments, we found that the two photon absorption coefficient (β) increases by as much as 14 times, i.e., 7.6 ± 0.4 to 112 ± 6 cm/GW, when the Ni doping is increased from 0% to 10%. The substantial enhancement in β is discussed in terms of the bandgap scaling and Ni doping. Furthermore, we also show that the optical bandgap measured by UV-Vis and photoluminescence spectroscopies, continuously redshift with increasing Ni doping concentration. We envision that the strong nonlinear optical properties together with their dilute magnetic effects, they form an important class of materials for potential applications in magneto-optical and integrated optical chips

Single-photon two-qubit entangled states: Preparation and measurement

International Nuclear Information System (INIS)

Kim, Yoon-Ho

2003-01-01

We implement experimentally a deterministic method to prepare and measure the so-called single-photon two-qubit entangled states or single-photon Bell states, in which the polarization and the spatial modes of a single photon each represent a quantum bit. All four single-photon Bell states can be easily prepared and measured deterministically using linear optical elements alone. We also discuss how this method can be used for the recently proposed single-photon two-qubit quantum cryptography scheme

Recent results on two-photon physics from Tasso and a review of measurements of the two-photon total cross section

International Nuclear Information System (INIS)

Kolanoski, H.

1983-03-01

Recent results on two-photon physics from the Tasso experiment are presented: the measurement of the two-photon production of Kanti K with the determination of the #betta##betta#-width of the f'(1515), an analysis of the angular correlations in the reaction #betta##betta#->rho 0 rho 0 ->π + π - π + π - and the observation of a narrow structure in the four pion mass spectrum around 2.1 GeV. In a separate part the experimental results on the total cross section for hadron production by two photons are reviewed. (orig.)

Slow light enhanced singlet exciton fission solar cells with a 126% yield of electrons per photon

International Nuclear Information System (INIS)

Thompson, Nicholas J.; Congreve, Daniel N.; Baldo, Marc A.; Goldberg, David; Menon, Vinod M.

2013-01-01

Singlet exciton fission generates two triplet excitons per absorbed photon. It promises to increase the power extracted from sunlight without increasing the number of photovoltaic junctions in a solar cell. We demonstrate solar cells with an external quantum efficiency of 126% by enhancing absorption in thin films of the singlet exciton fission material pentacene. The device structure exploits the long photon dwell time at the band edge of a distributed Bragg reflector to achieve enhancement over a broad range of angles. Measuring the reflected light from the solar cell establishes a lower bound of 137% for the internal quantum efficiency

Slow light enhanced singlet exciton fission solar cells with a 126% yield of electrons per photon

Energy Technology Data Exchange (ETDEWEB)

Thompson, Nicholas J.; Congreve, Daniel N.; Baldo, Marc A., E-mail: vmenon@qc.cuny.edu, E-mail: baldo@mit.edu [Energy Frontier Research Center for Excitonics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Goldberg, David; Menon, Vinod M., E-mail: vmenon@qc.cuny.edu, E-mail: baldo@mit.edu [Department of Physics, Queens College and Graduate Center, The City University of New York, Flushing, New York 11367 (United States)

2013-12-23

Singlet exciton fission generates two triplet excitons per absorbed photon. It promises to increase the power extracted from sunlight without increasing the number of photovoltaic junctions in a solar cell. We demonstrate solar cells with an external quantum efficiency of 126% by enhancing absorption in thin films of the singlet exciton fission material pentacene. The device structure exploits the long photon dwell time at the band edge of a distributed Bragg reflector to achieve enhancement over a broad range of angles. Measuring the reflected light from the solar cell establishes a lower bound of 137% for the internal quantum efficiency.

Luminosity measurements and two-photon physics with the DELPHI VSAT at LEP

International Nuclear Information System (INIS)

Jonsson, Per M.

1998-02-01

This thesis describes analysis of data from the DELPHI Very Small Angle Tagger (VSAT) calorimeter at LEP1. The VSAT consists of four Silicon-Tungsten calorimeter modules symmetrically positioned 7.7 meters away from the inter-action point. It measures elastically scattered electrons and positrons, Bhabha events, within the polar angular region between 5-12 mrad. Trigger efficiency and reconstruction procedures for the energy and position measurement of VSAT data are described. Off momentum electron background and online luminosity monitoring with the VSAT are also discussed. The extraction of various beam-parameters from analysis of the impact point of Bhabha pairs reveal the ability to measure variations in beam angles with a precision of 50 microrad. The relative luminosity measurement of the VSAT with a precision level of 0.1% for the 1993-1994 Z 0 scan is also presented. Through the study of double-tag-photon events, using the VSAT for measuring the energy of both scattered electrons, the behaviour of the total hadronic two-photon cross section is for the first time investigated up to invariant masses of 35 GeV

CdSe/AsS core-shell quantum dots: preparation and two-photon fluorescence.

Science.gov (United States)

Wang, Junzhong; Lin, Ming; Yan, Yongli; Wang, Zhe; Ho, Paul C; Loh, Kian Ping

2009-08-19

Arsenic(II) sulfide (AsS)-coated CdSe core-shell nanocrystals can be prepared by a cluster-complex deposition approach under mild conditions. At 60 degrees C, growth of an AsS shell onto a CdSe nanocrystal can be realized through the crystallization of a cluster complex of AsS/butylamine in a mixed solvent of isopropanol/chloroform. The new, type I core-shell nanocrystal exhibits markedly enhanced one-photon fluorescence as well two-photon upconversion fluorescence. The nanocrystals can be used for infrared-excited upconversion cellular labeling.

Thermodynamics of photon-enhanced thermionic emission solar cells

International Nuclear Information System (INIS)

Reck, Kasper; Hansen, Ole

2014-01-01

Photon-enhanced thermionic emission (PETE) cells in which direct photon energy as well as thermal energy can be harvested have recently been suggested as a new candidate for high efficiency solar cells. Here, we present an analytic thermodynamical model for evaluation of the efficiency of PETE solar cells including an analysis of the entropy production due to thermionic emission of general validity. The model is applied to find the maximum efficiency of a PETE cell for given cathode and anode work functions and temperatures

Increased fluorescence of PbS quantum dots in photonic crystals by excitation enhancement

Science.gov (United States)

Barth, Carlo; Roder, Sebastian; Brodoceanu, Daniel; Kraus, Tobias; Hammerschmidt, Martin; Burger, Sven; Becker, Christiane

2017-07-01

We report on the enhanced fluorescence of lead sulfide quantum dots interacting with leaky modes of slab-type silicon photonic crystals. The photonic crystal slabs were fabricated, supporting leaky modes in the near infrared wavelength range. Lead sulfite quantum dots which are resonant in the same spectral range were prepared in a thin layer above the slab. We selectively excited the leaky modes by tuning the wavelength and angle of incidence of the laser source and measured distinct resonances of enhanced fluorescence. By an appropriate experiment design, we ruled out directional light extraction effects and determined the impact of enhanced excitation. Three-dimensional numerical simulations consistently explain the experimental findings by strong near-field enhancements in the vicinity of the photonic crystal surface. Our study provides a basis for systematic tailoring of photonic crystals used in biological applications such as biosensing and single molecule detection, as well as quantum dot solar cells and spectral conversion applications.

Software-triggered contrast-enhanced three-dimensional MR angiography of the intracranial arteries.

Science.gov (United States)

Isoda, H; Takehara, Y; Isogai, S; Takeda, H; Tanaka, T; Takahashi, M; Nozaki, A; Sun, Y

2000-02-01

We investigated the effectiveness of software-triggered contrast-enhanced three-dimensional (3D) MR angiography in evaluating intracranial arteries. We studied 38 patients with suspected brain lesions. Imaging was performed using a 1.5-T superconducting MR system with a commercially available head coil. To monitor signal intensity changes we used software to place a tracker volume at the basilar artery or the internal carotid artery. A 20-ml bolus of gadodiamide hydrate was administered through the antecubital vein at a rate of 2-4 ml/sec, followed by a saline flush. Three-dimensional MR angiography using a spoiled gradient-echo sequence with centric K-space ordering was triggered by the arrival of the contrast bolus in the tracker volume. Imaging times ranged from 12 to 20 sec. We used MR images to assess the effectiveness of contrast-enhanced 3D MR angiography in revealing intracranial arteries with minimal venous overlap. The software triggered imaging on the arrival of the contrast bolus in 81.6% of examinations. In 77.6% of examinations, the resulting MR angiograms revealed intracranial arteries with minimal venous overlap. Software-triggered contrast-enhanced 3D MR angiography with centric K-space ordering is a promising technique for viewing intracranial arteries.

Hydrogenated TiO2 nanotube photonic crystals for enhanced photoelectrochemical water splitting.

Science.gov (United States)

Meng, Ming; Zhou, Sihua; Yang, Lun; Gan, Zhixing; Liu, Kuili; Tian, Fengshou; Zhu, Yu; Li, ChunYang; Liu, Weifeng; Yuan, Honglei; Zhang, Yan

2018-04-02

We report the design, fabrication and characterization of novel TiO 2 nanotube photonic crystals with a crystalline core/disordered shell structure as well as substantial oxygen vacancies for photoelectrochemical (PEC) water splitting. The novel TiO 2 nanotube photonic crystals are fabricated by annealing of anodized TiO 2 nanotube photonic crystals in hydrogen atmosphere at various temperatures. The optimized novel TiO 2 nanotube photonic crystals produce a maximal photocurrent density of 2.2 mA cm -2 at 0.22 V versus Ag/AgCl, which is two times higher that of the TiO 2 nanotube photonic crystals annealed in air. Such significant PEC performance improvement can be ascribed to synergistic effects of the disordered surface layer and oxygen vacancies. The reduced band gap owing to the disordered surface layer and localized states induced by oxygen vacancies can enhance the efficient utilization of visible light. In addition, the disordered surface layer and substantial oxygen vacancies can promote the efficiency for separation and transport of the photogenerated carriers. This work may open up new opportunities for the design and construction of the high efficient and low-cost PEC water splitting system.

Optical microscope using an interferometric source of two-color, two-beam entangled photons

Science.gov (United States)

Dress, William B.; Kisner, Roger A.; Richards, Roger K.

2004-07-13

Systems and methods are described for an optical microscope using an interferometric source of multi-color, multi-beam entangled photons. A method includes: downconverting a beam of coherent energy to provide a beam of multi-color entangled photons; converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; transforming at least a portion of the converged multi-color entangled photon beam by interaction with a sample to generate an entangled photon specimen beam; and combining the entangled photon specimen beam with an entangled photon reference beam within a single beamsplitter. An apparatus includes: a multi-refringent device providing a beam of multi-color entangled photons; a condenser device optically coupled to the multi-refringent device, the condenser device converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; a beam probe director and specimen assembly optically coupled to the condenser device; and a beam splitter optically coupled to the beam probe director and specimen assembly, the beam splitter combining an entangled photon specimen beam from the beam probe director and specimen assembly with an entangled photon reference beam.

Molecular engineering of two-photon fluorescent probes for bioimaging applications

Science.gov (United States)

Liu, Hong-Wen; Liu, Yongchao; Wang, Peng; Zhang, Xiao-Bing

2017-03-01

During the past two decades, two-photon microscopy (TPM), which utilizes two near-infrared photons as the excitation source, has emerged as a novel, attractive imaging tool for biological research. Compared with one-photon microscopy, TPM offers several advantages, such as lowering background fluorescence in living cells and tissues, reducing photodamage to biosamples, and a photobleaching phenomenon, offering better 3D spatial localization, and increasing penetration depth. Small-molecule-based two-photon fluorescent probes have been well developed for the detection and imaging of various analytes in biological systems. In this review, we will give a general introduction of molecular engineering of two-photon fluorescent probes based on different fluorescence response mechanisms for bioimaging applications during the past decade. Inspired by the desired advantages of small-molecule two-photon fluorescent probes in biological imaging applications, we expect that more attention will be devoted to the development of new two-photon fluorophores and applications of TPM in areas of bioanalysis and disease diagnosis.

Precision two-photon spectroscopy of alkali elements

Indian Academy of Sciences (India)

effect is eliminated if the wave vector of the photons is ka = −kb, i.e., the two beams .... atomic cesium, and the metre is (indirectly) defined from the wavelength of .... plasma absorb radiation, the electrical circuit parameters may vary and this .... two-photon excitation followed by an ionization step in Ca [71], Sr [72] and Gd [73] ...

Triggering photochemical processes in frozen extraterrestrial worlds by soft X-rays

International Nuclear Information System (INIS)

Pilling, Sergio; Bergantini, Alexandre; Vasconcelos, Fredson A; Rocha, Will R M

2015-01-01

We presents and experimental investigation on the effects produced by broad band soft X-rays (combined with a small fraction of vacuum ultra violet photons and possibly secondary elec-trons) on the surface of three moons of giant planets: Europa, Titan and Enceladus. Such environ-ments are constantly exposed to space ionizing agents (UV and soft X-rays photons, electrons and ions) allowing photodissociation processes, surface photochemistry and prebiotic chemistry. The processing of such spatial ices have promoted an enhancement in the chemical complexity, similar what may have happened in the early earth triggering the arising of life. (paper)

The CMS Electromagnetic Trigger: commissioning and performance toward the start of operation

International Nuclear Information System (INIS)

Zabi, A.

2009-01-01

The CMS electromagnetic calorimeter (ECAL) has been designed to precisely measure electron and photon energy. It is made of 75848 lead tungstate (PbWO 4 ) crystals and its characteristics have been optimized for the search of the Higgs boson in its two photons decay mode. In view of the high interaction rate at the Large Hadron Collider (Lhc), CMS implements a sophisticated online selection system that achieves a rejection factor of nearly 10 6 . In the intense hadronic environment, the ECAL trigger system provides a powerful tool to select interesting physics events which may contain electrons or photons in their final states. Comic ray data recorded by the CMS experiment have been analyzed in order to estimate the ECAL trigger performance in terms of efficiency.

One-, two- and three-photon experiments

International Nuclear Information System (INIS)

Caldwell, D.O.; Cumalat, J.P.; Eisner, A.M.

1977-01-01

The results of experiments to provide further information about parton structure by getting into the deep inelastic region of π 0 electroproduction are presented. To analyse whether the interference between two- and three- photon exchange would give a difference between e + and e - scattering has been measured using the 20.5 GeV electron and 13.5 GeV positron beams and a hydrogen target. No evidence for the two-photon exchange has been observed within the experimental errors. Although the e + -e - difference in the three-photon experiment has been certainly + → γ/e - → γ= 1.09+-0.03. It yields a rough value of the parton mean cubed charge of 1.1+-0.5. The mere existence of the result provides strong support for the idea of constituent particles

The development of efficient two-photon singlet oxygen sensitizers

DEFF Research Database (Denmark)

Nielsen, Christian Benedikt

The development of efficient two-photon singlet oxygen sensitizers is addressed focusing on organic synthesis. Photophysical measurements were carried out on new lipophilic molecules, where two-photon absorption cross sections and singlet oxygen quantumyields were measured. Design principles...... for making efficient two-photon singlet oxygen sensitizers were then constructed from these results. Charge-transfer in the excited state of the prepared molecules was shown to play a pivotal role in the generationof singlet oxygen. This was established through studies of substituent effects on both...... the singlet oxygen yield and the two-photon absorption cross section, where it was revealed that a careful balancing of the amount of charge transfer present in theexcited state of the sensitizer is necessary to obtain both a high singlet oxygen quantum yield and a high two-photon cross section. An increasing...

Silole-Based Red Fluorescent Organic Dots for Bright Two-Photon Fluorescence In vitro Cell and In vivo Blood Vessel Imaging.

Science.gov (United States)

Chen, Bin; Feng, Guangxue; He, Bairong; Goh, Chiching; Xu, Shidang; Ramos-Ortiz, Gabriel; Aparicio-Ixta, Laura; Zhou, Jian; Ng, Laiguan; Zhao, Zujin; Liu, Bin; Tang, Ben Zhong

2016-02-10

Robust luminescent dyes with efficient two-photon fluorescence are highly desirable for biological imaging applications, but those suitable for organic dots fabrication are still rare because of aggregation-caused quenching. In this work, a red fluorescent silole, 2,5-bis[5-(dimesitylboranyl)thiophen-2-yl]-1-methyl-1,3,4-triphenylsilole ((MesB)2 DTTPS), is synthesized and characterized. (MesB)2 DTTPS exhibits enhanced fluorescence efficiency in nanoaggregates, indicative of aggregation-enhanced emission (AEE). The organic dots fabricated by encapsulating (MesB)2 DTTPS within lipid-PEG show red fluorescence peaking at 598 nm and a high fluorescence quantum yield of 32%. Upon excitation at 820 nm, the dots show a large two-photon absorption cross section of 3.43 × 10(5) GM, which yields a two-photon action cross section of 1.09 × 10(5) GM. These (MesB)2 DTTPS dots show good biocompatibility and are successfully applied to one-photon and two-photon fluorescence imaging of MCF-7 cells and two-photon in vivo visualization of the blood vascular of mouse muscle in a high-contrast and noninvasive manner. Moreover, the 3D blood vasculature located at the mouse ear skin with a depth of over 100 μm can also be visualized clearly, providing the spatiotemporal information about the whole blood vascular network. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition

Energy Technology Data Exchange (ETDEWEB)

Lee, Su-Yong; Kim, Ho-Joon [Department of Physics, Texas A and M University at Qatar, P.O. Box 23874, Doha (Qatar); Ji, Se-Wan [School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of); Nha, Hyunchul [Department of Physics, Texas A and M University at Qatar, P.O. Box 23874, Doha (Qatar); Institute fuer Quantenphysik, Universitaet Ulm, D-89069 Ulm (Germany)

2011-07-15

We investigate how the entanglement properties of a two-mode state can be improved by performing a coherent superposition operation ta+ra{sup {dagger}} of photon subtraction and addition, proposed by Lee and Nha [Phys. Rev. A 82, 053812 (2010)], on each mode. We show that the degree of entanglement, the Einstein-Podolsky-Rosen-type correlation, and the performance of quantum teleportation can be all enhanced for the output state when the coherent operation is applied to a two-mode squeezed state. The effects of the coherent operation are more prominent than those of the mere photon subtraction a and the addition a{sup {dagger}} particularly in the small-squeezing regime, whereas the optimal operation becomes the photon subtraction (case of r=0) in the large-squeezing regime.

Interference of two photons in parametric down conversion

International Nuclear Information System (INIS)

Ghosh, R.; Hong, C.K.; Ou, Z.Y.; Mandel, L.

1986-01-01

A theoretical treatment is given of the process in which the two photons produced simultaneously in the parametric frequency splitting of light are allowed to interfere. It is shown that, while there is no interference in the usual sense involving quantities that are of the second order in the field, fourth-order interference effects are present. These may be revealed by measuring the joint probability of detecting two photons at two points x,x' in the interference plane with photoelectric detectors as a function of the separation x-x'. The probability exhibits a cosine modulation with x-x', with visibility that can approach 100%, even though the integration time in the experiment may greatly exceed the reciprocal bandwidth of the photons. The interference effect has a nonclassical origin and implies a violation of local realism in the highly correlated two-photon state

Slow-light-enhanced upconversion for photovoltaic applications in one-dimensional photonic crystals.

Science.gov (United States)

Johnson, Craig M; Reece, Peter J; Conibeer, Gavin J

2011-10-15

We present an approach to realizing enhanced upconversion efficiency in erbium (Er)-doped photonic crystals. Slow-light-mode pumping of the first Er excited state transition can result in enhanced emission from higher-energy levels that may lead to finite subbandgap external quantum efficiency in crystalline silicon solar cells. Using a straightforward electromagnetic model, we calculate potential field enhancements of more than 18× within he slow-light mode of a one-dimensional photonic crystal and discuss design trade-offs and considerations for photovoltaics.

Sub-megahertz linewidth single photon source

Directory of Open Access Journals (Sweden)

Markus Rambach

2016-12-01

Full Text Available We report 100% duty cycle generation of sub-MHz single photon pairs at the rubidium D1 line using cavity-enhanced spontaneous parametric downconversion. The temporal intensity cross correlation function exhibits a bandwidth of 666±16 kHz for the single photons, an order of magnitude below the natural linewidth of the target transition. A half-wave plate inside our cavity helps to achieve triple resonance between pump, signal, and idler photon, reducing the bandwidth and simplifying the locking scheme. Additionally, stabilisation of the cavity to the pump frequency enables the 100% duty cycle. The quantum nature of the source is confirmed by the idler-triggered second-order autocorrelation function at τ=0 to be gs,s(2(0= 0.016±0.002 for a heralding rate of 5 kHz. The generated photons are well-suited for storage in quantum memory schemes with sub-natural linewidths, such as gradient echo memories.

Generation of Fourier-transform-limited heralded single photons

International Nuclear Information System (INIS)

U'Ren, Alfred B.; Jeronimo-Moreno, Yasser; Garcia-Gracia, Hipolito

2007-01-01

In this paper we study the spectral (temporal) properties of heralded single photon wave packets, triggered by the detection of an idler photon in the process of parametric down conversion. The generated single photons are studied within the framework of the chronocyclic Wigner function, from which the single photon spectral width and temporal duration can be computed. We derive specific conditions on the two-photon joint spectral amplitude which result in both pure and Fourier-transform-limited heralded single photons. Likewise, we present specific source geometries which lead to the fulfillment of these conditions and show that one of these geometries leads, for a given pump bandwidth, to the temporally shortest possible heralded single photon wave packets

Enhancement of the fluorescence intensity of DNA intercalators using nano-imprinted 2-dimensional photonic crystal

International Nuclear Information System (INIS)

Endo, Tatsuro; Ueda, China; Hisamoto, Hideaki; Kajita, Hiroshi; Okuda, Norimichi; Tanaka, Satoru

2013-01-01

We have fabricated polymer-based 2-dimensional photonic crystals that play a key role in enhancing the fluorescence of DNA intercalators. Highly ordered 2-dimensional photonic crystals possessing triangle-shaped and nm-sized hole arrays were fabricated on a 100 μm thick polymer film using nano-imprint lithography. Samples of double-stranded DNAs (sizes: 4361 and 48502 bp; concentration: 1 pM to 10 nM) were adsorbed on the surface of the 2-dimensional photonic crystal by electrostatic interactions and then treated with intercalators. It is found that the fluorescence intensity of the intercalator is enhanced by a factor of up to 10 compared to the enhancement in the absence of the 2-dimensional photonic crystal. Fluorescence intensity increases with increasing length and concentration of the DNAs. If the 2-dimensional photonic crystal is used as a Bragg reflection mirror, the enhancement of fluorescence intensity can be easily observed using a conventional spectrofluorometer. These results suggest that the printed photonic crystal offers a great potential for highly sensitive intercalator-based fluorescent detection of DNAs. (author)

Slow-light-enhanced gain in active photonic crystal waveguides

DEFF Research Database (Denmark)

Ek, Sara; Hansen, Per Lunnemann; Chen, Yaohui

2014-01-01

Passive photonic crystals have been shown to exhibit a multitude of interesting phenomena, including slow-light propagation in line-defect waveguides. It was suggested that by incorporating an active material in the waveguide, slow light could be used to enhance the effective gain of the material......, which would have interesting application prospects, for example enabling ultra-compact optical amplifiers for integration in photonic chips. Here we experi- mentally investigate the gain of a photonic crystal membrane structure with embedded quantum wells. We find that by solely changing the photonic...... crystal structural parameters, the maximum value of the gain coefficient can be increased compared with a ridge waveguide structure and at the same time the spectral position of the peak gain be controlled. The experimental results are in qualitative agreement with theory and show that gain values similar...

Photon enhanced thermionic emission

Science.gov (United States)

Schwede, Jared; Melosh, Nicholas; Shen, Zhixun

2014-10-07

Photon Enhanced Thermionic Emission (PETE) is exploited to provide improved efficiency for radiant energy conversion. A hot (greater than 200.degree. C.) semiconductor cathode is illuminated such that it emits electrons. Because the cathode is hot, significantly more electrons are emitted than would be emitted from a room temperature (or colder) cathode under the same illumination conditions. As a result of this increased electron emission, the energy conversion efficiency can be significantly increased relative to a conventional photovoltaic device. In PETE, the cathode electrons can be (and typically are) thermalized with respect to the cathode. As a result, PETE does not rely on emission of non-thermalized electrons, and is significantly easier to implement than hot-carrier emission approaches.

Two-Photon Absorption in Organometallic Bromide Perovskites

KAUST Repository

Walters, Grant

2015-07-21

Organometallic trihalide perovskites are solution processed semiconductors that have made great strides in third generation thin film light harvesting and light emitting optoelectronic devices. Recently it has been demonstrated that large, high purity single crystals of these perovskites can be synthesized from the solution phase. These crystals’ large dimensions, clean bandgap, and solid-state order, have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW-1 at 800 nm, comparable to epitaxial single crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

Two-Photon Absorption in Organometallic Bromide Perovskites

KAUST Repository

Walters, Grant; Sutherland, Brandon R; Hoogland, Sjoerd; Shi, Dong; Comin, Riccardo; Sellan, Daniel P.; Bakr, Osman; Sargent, Edward H.

2015-01-01

Organometallic trihalide perovskites are solution processed semiconductors that have made great strides in third generation thin film light harvesting and light emitting optoelectronic devices. Recently it has been demonstrated that large, high purity single crystals of these perovskites can be synthesized from the solution phase. These crystals’ large dimensions, clean bandgap, and solid-state order, have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW-1 at 800 nm, comparable to epitaxial single crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

Monte Carlo simulation of two-photon processes

International Nuclear Information System (INIS)

Daverveldt, P.H.W.M.

1985-01-01

During the last two decades e + e - collider experiments provided physicists with a wealth of important discoveries concerning elementary particle physics. This thesis explains in detail how the Monte Carlo approach can be applied to establish the comparison between two-photon experiments and theory. The author describes the main motives for and objectives of two-photon research. He defines the kinematics and pays attention to some special kinematical regions. Also a popular approximation for the exact differential cross section is reviewed. Next he discusses the calculation of the complete lowest order cross section for processes with four leptons in the final state and for reactions such as e + e - →e + e - qanti q, e + e - →μ + μ - qanti q. Radiative corrections to the multiperipheral diagrams are considered. The author explains in detail the distinction between soft and hard photon corrections which turns out to be somewhat more tricky than in the case of radiative corrections to one-photon processes. Finally, he presents some results which were obtained by using the event generators. (Auth.)

Enhanced photoresponsivity in graphene-silicon slow-light photonic crystal waveguides

International Nuclear Information System (INIS)

Zhou, Hao; Gu, Tingyi; McMillan, James F.; Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee; Feng, Guoying; Zhou, Shouhuan; Wong, Chee Wei

2016-01-01

We demonstrate the enhanced fast photoresponsivity in graphene hybrid structures by combining the ultrafast dynamics of graphene with improved light-matter interactions in slow-light photonic crystal waveguides. With a 200 μm interaction length, a 0.8 mA/W photoresponsivity is achieved in a graphene-silicon Schottky-like photodetector, with an operating bandwidth in excess of 5 GHz and wavelength range at least from 1480 nm to 1580 nm. Fourfold enhancement of the photocurrent is observed in the slow light region, compared to the wavelength far from the photonic crystal bandedge, for a chip-scale broadband fast photodetector.

Enhancement of thermal photon production in event-by-event hydrodynamics

International Nuclear Information System (INIS)

Chatterjee, Rupa; Holopainen, Hannu; Renk, Thorsten; Eskola, Kari J.

2011-01-01

Thermal photon emission is widely believed to reflect properties of the earliest, hottest evolution stage of the medium created in ultrarelativistic heavy-ion collisions. Previous computations of photon emission have been carried out using a hydrodynamical medium description with smooth, averaged initial conditions. Recently, more sophisticated hydrodynamical models that calculate observables by averaging over many evolutions with event-by-event fluctuating initial conditions (ICs) have been developed. Given their direct connection to the early time dynamics, thermal photon emission appears to be an ideal observable to probe fluctuations in the medium initial state. In this work, we demonstrate that including fluctuations in the ICs may lead to an enhancement of the thermal photon yield of about a factor of 2 in the region 2 T <4 GeV/c (where thermal photon production dominates the direct photon yield) compared to a scenario using smooth, averaged ICs. Consequently, a much better agreement with PHENIX data is found. This can be understood in terms of the strong temperature dependence of thermal photon production, translating into a sensitivity to the presence of hotspots in an event and thus establishing thermal photons as a suitable probe to characterize IC fluctuations.

Stimulated emission depletion following two photon excitation

OpenAIRE

Marsh, R. J.; Armoogum, D. A.; Bain, A. J.

2002-01-01

The technique of stimulated emission depletion of fluorescence (STED) from a two photon excited molecular population is demonstrated in the S, excited state of fluorescein in ethylene glycol and methanol. Two photon excitation (pump) is achieved using the partial output of a regeneratively amplified Ti:Sapphire laser in conjunction with an optical parametric amplifier whose tuneable output provides a synchronous depletion (dump) pulse. Time resolved fluorescence intensity and anisotropy measu...

Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

International Nuclear Information System (INIS)

McConnell, Gail; Riis, Erling

2004-01-01

We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM

One-bit photon polarization in two-photon experiments. An information mechanics perspective

International Nuclear Information System (INIS)

Kantor, F.W.

1991-01-01

In this paper is presented a detailed treatment of amount and representation of photon polarization information in the two-photon experiments of Aspect, Grangier, and Roger, seeking to test Einstein, Podolsky, and Rosen's thought experiment. Newton's mechanics, Einstein's relativistic mechanics, and quantum mechanics do not treat as fundamental the amount and representation of information in physical systems. The line of reasoning presented here was reached via Kantor's information mechanics. The information bookkeeping presented here appears to offer a simple, physical insight into what the apparatus and the photons are doing together

Entanglement of two-qubit photon beam by magnetic field

Energy Technology Data Exchange (ETDEWEB)

Levin, A.D.; Castro, R.A. [University of Sao Paulo, Institute of Physics, CP 66318, Sao Paulo (Brazil); Gitman, D.M. [University of Sao Paulo, Institute of Physics, CP 66318, Sao Paulo (Brazil); P.N. Lebedev Physical Institute, Moscow (Russian Federation); Tomsk State University, Tomsk (Russian Federation)

2014-09-15

We study the possibility of affecting the entanglement in a two-qubit system consisting of two photons with different fixed frequencies but with two arbitrary linear polarizations, moving in the same direction, with the help of an applied external magnetic field. The interaction between the magnetic field and the photons in our model is achieved through intermediate electrons that interact both with the photons and the magnetic field. The possibility of an exact theoretical analysis of this scheme is based on well-known exact solutions that describe the interaction of an electron subjected to an external magnetic field (or a medium of electrons not interacting with each other) with a quantized field of two photons. We adapt these exact solutions to the case under consideration. Using explicit wave functions for the resulting electromagnetic field, we calculate the entanglement measures (the information and the Schmidt ones) of the photon beam as functions of the applied magnetic field and the parameters of the electron medium. (orig.)

Mass distribution for the two-photon channel

CERN Multimedia

ATLAS, collaboration

2012-01-01

Mass distribution for the two-photon channel. The strongest evidence for this new particle comes from analysis of events containing two photons. The smooth dotted line traces the measured background from known processes. The solid line traces a statistical fit to the signal plus background. The new particle appears as the excess around 126.5 GeV. The full analysis concludes that the probability of such a peak is three chances in a million.

Therapeutic-Ultrasound-Triggered Shape Memory of a Melamine-Enhanced Poly(vinyl alcohol) Physical Hydrogel.

Science.gov (United States)

Li, Guo; Yan, Qiang; Xia, Hesheng; Zhao, Yue

2015-06-10

Therapeutic-ultrasound-triggered shape memory was demonstrated for the first time with a melamine-enhanced poly(vinyl alcohol) (PVA) physical hydrogel. The addition of a small amount of melamine (up to 1.5 wt %) in PVA results in a strong hydrogel due to the multiple H-bonding between the two constituents. A temporary shape of the hydrogel can be obtained by deformation of the hydrogel (∼65 wt % water) at room temperature, followed by fixation of the deformation by freezing/thawing the hydrogel under strain, which induces crystallization of PVA. We show that the ultrasound delivered by a commercially available device designed for the patient's pain relief could trigger the shape recovery process as a result of ultrasound-induced local heating in the hydrogel that melts the crystallized PVA cross-linking. This hydrogel is thus interesting for potential applications because it combines many desirable properties, being mechanically strong, biocompatible, and self-healable and displaying the shape memory capability triggered by a physiological stimulus.

Enhanced Gain in Slow-Light Photonic Crystal Waveguides with Embedded Quantum Dots

DEFF Research Database (Denmark)

Ek, Sara; Hansen, Per Lunnemann; Semenova, Elizaveta

2011-01-01

We experimentally demonstrate enhanced gain in the slow-light regime of quantum dot photonic crystal waveguide slabs. These are promising results for future compact devices for terabit/s communication, such as compact optical amplifiers and mode-locked lasers.......We experimentally demonstrate enhanced gain in the slow-light regime of quantum dot photonic crystal waveguide slabs. These are promising results for future compact devices for terabit/s communication, such as compact optical amplifiers and mode-locked lasers....

Cascaded two-photon nonlinearity in a one-dimensional waveguide with multiple two-level emitters

Science.gov (United States)

Roy, Dibyendu

2013-01-01

We propose and theoretically investigate a model to realize cascaded optical nonlinearity with few atoms and photons in one-dimension (1D). The optical nonlinearity in our system is mediated by resonant interactions of photons with two-level emitters, such as atoms or quantum dots in a 1D photonic waveguide. Multi-photon transmission in the waveguide is nonreciprocal when the emitters have different transition energies. Our theory provides a clear physical understanding of the origin of nonreciprocity in the presence of cascaded nonlinearity. We show how various two-photon nonlinear effects including spatial attraction and repulsion between photons, background fluorescence can be tuned by changing the number of emitters and the coupling between emitters (controlled by the separation). PMID:23948782

The ATLAS High-Level Calorimeter Trigger in Run-2

CERN Document Server

Wiglesworth, Craig; The ATLAS collaboration

2018-01-01

The ATLAS Experiment uses a two-level triggering system to identify and record collision events containing a wide variety of physics signatures. It reduces the event rate from the bunch-crossing rate of 40 MHz to an average recording rate of 1 kHz, whilst maintaining high efficiency for interesting collision events. It is composed of an initial hardware-based level-1 trigger followed by a software-based high-level trigger. A central component of the high-level trigger is the calorimeter trigger. This is responsible for processing data from the electromagnetic and hadronic calorimeters in order to identify electrons, photons, taus, jets and missing transverse energy. In this talk I will present the performance of the high-level calorimeter trigger in Run-2, noting the improvements that have been made in response to the challenges of operating at high luminosity.

CERN: A tale of two photons

International Nuclear Information System (INIS)

Anon.

1993-01-01

When precision data from the several million Zs carefully collected over several years by the four big experiments - Aleph, Delphi, L3 and Opal - at CERN's LEP electron-positron collider have otherwise consistently underlined conventional physics, a hint of something unexplained quickly packs the seminar rooms. In 1991, the L3 experiment turned up two examples of Z decays producing a muon pair accompanied by a widely separated pair of high energy photons, with the photon pair in each case taking some 60 GeV of energy (actually 58.8 and 59.0 GeV). Nothing to get excited about at the time, but ongoing data analysis tuned into this channel. This year two more events turned up, one again with a muon pair accompanied by a 60 GeV photon pair, the other with an electron (electron-positron) pair and a 62 GeV photon pair. At first L3 preferred to keep this quiet, and the news was not announced at the major international meeting in Dallas last August. The first public announcement of the four unexplained events (out of a total of 1.6 million Z decays) came in a LEP Experiments Committee session at CERN in October

Two-dimensional plasma photonic crystals in dielectric barrier discharge

International Nuclear Information System (INIS)

Fan Weili; Dong Lifang; Zhang Xinchun

2010-01-01

A series of two-dimensional plasma photonic crystals have been obtained by filaments' self-organization in atmospheric dielectric barrier discharge with two water electrodes, which undergo the transition from square to square superlattice and finally to the hexagon. The spatio-temporal behaviors of the plasma photonic crystals in nanosecond scale have been studied by optical method, which show that the plasma photonic crystal is actually an integration of different transient sublattices. The photonic band diagrams of the transverse electric (TE) mode and transverse magnetic mode for each sublattice of these plasma photonic crystals have been investigated theoretically. A wide complete band gap is formed in the hexagonal plasma photonic crystal with the TE mode. The changes of the band edge frequencies and the band gap widths in the evolvement of different structures are studied. A kind of tunable plasma photonic crystal which can be controlled both in space and time is suggested.

Broadband enhancement of single photon emission and polarization dependent coupling in silicon nitride waveguides.

Science.gov (United States)

Bisschop, Suzanne; Guille, Antoine; Van Thourhout, Dries; Hens, Zeger; Brainis, Edouard

2015-06-01

Single-photon (SP) sources are important for a number of optical quantum information processing applications. We study the possibility to integrate triggered solid-state SP emitters directly on a photonic chip. A major challenge consists in efficiently extracting their emission into a single guided mode. Using 3D finite-difference time-domain simulations, we investigate the SP emission from dipole-like nanometer-sized inclusions embedded into different silicon nitride (SiNx) photonic nanowire waveguide designs. We elucidate the effect of the geometry on the emission lifetime and the polarization of the emitted SP. The results show that highly efficient and polarized SP sources can be realized using suspended SiNx slot-waveguides. Combining this with the well-established CMOS-compatible processing technology, fully integrated and complex optical circuits for quantum optics experiments can be developed.

Phonon-Assisted Two-Photon Interference from Remote Quantum Emitters.

Science.gov (United States)

Reindl, Marcus; Jöns, Klaus D; Huber, Daniel; Schimpf, Christian; Huo, Yongheng; Zwiller, Val; Rastelli, Armando; Trotta, Rinaldo

2017-07-12

Photonic quantum technologies are on the verge of finding applications in everyday life with quantum cryptography and quantum simulators on the horizon. Extensive research has been carried out to identify suitable quantum emitters and single epitaxial quantum dots have emerged as near-optimal sources of bright, on-demand, highly indistinguishable single photons and entangled photon-pairs. In order to build up quantum networks, it is essential to interface remote quantum emitters. However, this is still an outstanding challenge, as the quantum states of dissimilar "artificial atoms" have to be prepared on-demand with high fidelity and the generated photons have to be made indistinguishable in all possible degrees of freedom. Here, we overcome this major obstacle and show an unprecedented two-photon interference (visibility of 51 ± 5%) from remote strain-tunable GaAs quantum dots emitting on-demand photon-pairs. We achieve this result by exploiting for the first time the full potential of a novel phonon-assisted two-photon excitation scheme, which allows for the generation of highly indistinguishable (visibility of 71 ± 9%) entangled photon-pairs (fidelity of 90 ± 2%), enables push-button biexciton state preparation (fidelity of 80 ± 2%) and outperforms conventional resonant two-photon excitation schemes in terms of robustness against environmental decoherence. Our results mark an important milestone for the practical realization of quantum repeaters and complex multiphoton entanglement experiments involving dissimilar artificial atoms.

Thermalization of a two-dimensional photonic gas in a `white wall' photon box

Science.gov (United States)

Klaers, Jan; Vewinger, Frank; Weitz, Martin

2010-07-01

Bose-Einstein condensation, the macroscopic accumulation of bosonic particles in the energetic ground state below a critical temperature, has been demonstrated in several physical systems. The perhaps best known example of a bosonic gas, blackbody radiation, however exhibits no Bose-Einstein condensation at low temperatures. Instead of collectively occupying the lowest energy mode, the photons disappear in the cavity walls when the temperature is lowered-corresponding to a vanishing chemical potential. Here we report on evidence for a thermalized two-dimensional photon gas with a freely adjustable chemical potential. Our experiment is based on a dye-filled optical microresonator, acting as a `white wall' box for photons. Thermalization is achieved in a photon-number-conserving way by photon scattering off the dye molecules, and the cavity mirrors provide both an effective photon mass and a confining potential-key prerequisites for the Bose-Einstein condensation of photons. As a striking example of the unusual system properties, we demonstrate a yet unobserved light concentration effect into the centre of the confining potential, an effect with prospects for increasing the efficiency of diffuse solar light collection.

Tapered photonic crystal fibers for blue-enhanced supercontinuum generation

DEFF Research Database (Denmark)

Møller, Uffe; Sørensen, Simon Toft; Larsen, Casper

2012-01-01

Tapering of photonic crystal fibers is an effective way of shifting the blue edge of a supercontinuum spectrum down in the deep-blue. We discuss the optimum taper profile for enhancing the power in the blue edge....

Zak phase induced multiband waveguide by two-dimensional photonic crystals.

Science.gov (United States)

Yang, Yuting; Xu, Tao; Xu, Yun Fei; Hang, Zhi Hong

2017-08-15

Interface states in photonic crystals provide efficient approaches to control the flow of light. Photonic Zak phase determines the bulk band properties of photonic crystals, and, by assembling two photonic crystals with different bulk band properties together, deterministic interface states can be realized. By translating each unit cell of a photonic crystal by half the lattice constant, another photonic crystal with identical common gaps but a different Zak phase at each photonic band can be created. By assembling these two photonic crystals together, multiband waveguide can thus be easily created and then experimentally characterized. Our experimental results have good agreement with numerical simulations, and the propagation properties of these measured interface states indicate that this new type of interface state will be a good candidate for future applications of optical communications.

The ATLAS Trigger Menu design for higher luminosities in Run 2

CERN Document Server

Torro Pastor, Emma; The ATLAS collaboration

2018-01-01

The ATLAS experiment aims at recording about 1 kHz of physics collisions, starting with an LHC design bunch crossing rate of 40 MHz. To reduce the large background rate while maintaining a high selection efficiency for rare physics events (such as beyond the Standard Model physics), a two-level trigger system is used. Events are selected based on physics signatures such as the presence of energetic leptons, photons, jets or large missing energy. The trigger system exploits topological information, as well as multivariate methods to carry out the necessary physics filtering for the many analyses that are pursued by the ATLAS community. In total, the ATLAS online selection consists of nearly two thousand individual triggers. A Trigger Menu is the compilation of these triggers, it specifies the physics selection algorithms to be used during data taking and the rate and bandwidth a given trigger is allocated. Trigger menus must reflect the physics goals of the collaboration for a given run, but also take into con...

Efficient fiber-coupled single-photon source based on quantum dots in a photonic-crystal waveguide

DEFF Research Database (Denmark)

Daveau, Raphaël S.; Balram, Krishna C.; Pregnolato, Tommaso

2017-01-01

Many photonic quantum information processing applications would benefit from a high brightness, fiber-coupled source of triggered single photons. Here, we present a fiber-coupled photonic-crystal waveguide (PCWG) singlephoton source relying on evanescent coupling of the light field from a tapered...

Dominant two-loop electroweak corrections to the hadroproduction of a pseudoscalar Higgs boson and its photonic decay

International Nuclear Information System (INIS)

Brod, J.; Kniehl, B.A.

2008-01-01

We present the dominant two-loop electroweak corrections to the partial decay widths to gluon jets and prompt photons of the neutral CP-odd Higgs boson A 0 , with mass M A 0 W , in the two-Higgs-doublet model for low to intermediate values of the ratio tan β=v 2 /v 1 of the vacuum expectation values. They apply as they stand to the production cross sections in hadronic and two-photon collisions, at the Tevatron, the LHC, and a future photon collider. The appearance of three γ 5 matrices in closed fermion loops requires special care in the dimensional regularization of ultraviolet divergences. The corrections are negative and amount to several percent, so that they fully compensate or partly screen the enhancement due to QCD corrections. (orig.)

Emulation of two-dimensional photonic crystal defect modes in a photonic crystal with a three-dimensional photonic band gap

Energy Technology Data Exchange (ETDEWEB)

Povinelli, M. L.; Johnson, Steven G.; Fan, Shanhui; Joannopoulos, J. D.

2001-08-15

Using numerical simulations, we demonstrate the construction of two-dimensional- (2D-) like defect modes in a recently proposed 3D photonic crystal structure. These modes, which are confined in all three dimensions by a complete photonic band gap, bear a striking similarity to those in 2D photonic crystals in terms of polarization, field profile, and projected band structures. It is expected that these results will greatly facilitate the observation of widely studied 2D photonic-crystal phenomena in a realistic, 3D physical system.

Emulation of two-dimensional photonic crystal defect modes in a photonic crystal with a three-dimensional photonic band gap

International Nuclear Information System (INIS)

Povinelli, M. L.; Johnson, Steven G.; Fan, Shanhui; Joannopoulos, J. D.

2001-01-01

Using numerical simulations, we demonstrate the construction of two-dimensional- (2D-) like defect modes in a recently proposed 3D photonic crystal structure. These modes, which are confined in all three dimensions by a complete photonic band gap, bear a striking similarity to those in 2D photonic crystals in terms of polarization, field profile, and projected band structures. It is expected that these results will greatly facilitate the observation of widely studied 2D photonic-crystal phenomena in a realistic, 3D physical system

Targeted two-photon photodynamic therapy for the treatment of subcutaneous tumors

Science.gov (United States)

Spangler, Charles W.; Starkey, Jean R.; Meng, Fanqing; Gong, Aijun; Drobizhev, Mikhail; Rebane, Aleksander; Moss, B.

2005-04-01

Photodynamic therapy (PDT) has developed into a mature technology over the past several years, and is currently being exploited for the treatment of a variety of cancerous tumors, and more recently for age-related wet macular degeneration of the eye. However, there are still some unresolved problems with PDT that are retarding a more general acceptance in clinical settings, and thus, for the most part, the treatment of most cancerous rumors still involves some combination of invasive surgery, chemotherapy and radiation treatment, particularly subcutaneous tumors. Currently approved PDT agents are activated in the Visible portion of the spectrum below 700 nm, Laser light in this spectral region cannot penetrate the skin more than a few millimeters, and it would be more desirable if PDT could be initiated deep in the Near-infrared (NIR) in the tissue transparency window (700-1000 nm). MPA Technologies, Inc. and Rasiris, Inc. have been co-developing new porphyrin PDT designed to have greatly enhanced intrinsic two-photon cross-sections (>800 GM units) whose two-photon absorption maxima lie deep in the tissue transparency window (ca. 780-850 nm), and have solubility characteristics that would allow for direct IV injection into animal models. Classical PDT also suffers from the lengthy time necessary for accumulation at the tumor site, a relative lack of discrimination between healthy and diseased tissue, particularly at the tumor margins, and difficulty in clearing from the system in a reasonable amount of time post-PDT. We have recently discovered a new design paradigm for the delivery of our two-photon activated PDT agents by incorporating the porphyrins into a triad ensemble that includes a small molecule targeting agent that directs the triad to over-expressed tumor receptor sites, and a NIR one-photon imaging agent that allows the tracking of the triad in terms of accumulation and clearance rates. We are currently using these new two-photon PDT triads in efficacy

Enhanced Emission from Single Isolated Gold Quantum Dots Investigated Using Two-Photon-Excited Fluorescence Near-Field Scanning Optical Microscopy.

Science.gov (United States)

Abeyasinghe, Neranga; Kumar, Santosh; Sun, Kai; Mansfield, John F; Jin, Rongchao; Goodson, Theodore

2016-12-21

New approaches in molecular nanoscopy are greatly desired for interrogation of biological, organic, and inorganic objects with sizes below the diffraction limit. Our current work investigates emergent monolayer-protected gold quantum dots (nanoclusters, NCs) composed of 25 Au atoms by utilizing two-photon-excited fluorescence (TPEF) near-field scanning optical microscopy (NSOM) at single NC concentrations. Here, we demonstrate an approach to synthesize and isolate single NCs on solid glass substrates. Subsequent investigation of the NCs using TPEF NSOM reveals that, even when they are separated by distances of several tens of nanometers, we can excite and interrogate single NCs individually. Interestingly, we observe an enhanced two-photon absorption (TPA) cross section for single Au 25 NCs that can be attributed to few-atom local field effects and to local field-induced microscopic cascading, indicating their potential for use in ultrasensitive sensing, disease diagnostics, cancer cell therapy, and molecular computers. Finally, we report room-temperature aperture-based TPEF NSOM imaging of these NCs for the first time at 30 nm point resolution, which is a ∼5-fold improvement compared to the previous best result for the same technique. This report unveils the unique combination of an unusually large TPA cross section and the high photostability of Au NCs to (non-destructively) investigate stable isolated single NCs using TPEF NSOM. This is the first reported optical study of monolayer-protected single quantum clusters, opening some very promising opportunities in spectroscopy of nanosized objects, bioimaging, ultrasensitive sensing, molecular computers, and high-density data storage.

Performance of ATLAS L1 Calorimeter Trigger with data

CERN Document Server

Bracinik, J; The ATLAS collaboration

2010-01-01

The ATLAS first-level calorimeter trigger is a hardware-based system designed to identify high-pT jets, electron/photon and tau candidates and to measure total and missing ET in the ATLAS calorimeters. After more than two years of commissioning in situ with calibration data and cosmic rays, the system has now been extensively used to select the most interesting proton-proton collision events. Final tuning of timing and energy calibration has been carried out in 2010 to improve the trigger response to physics objects. An analysis of the performance of the level-1 calorimeter trigger will be presented, along with the techniques used to achieve these results.

Two-photon absorption and two-photon circular dichroism of hexahelicene derivatives: a study of the effect of the nature of intramolecular charge transfer

Czech Academy of Sciences Publication Activity Database

Díaz, C.; Vesga, Y.; Echevarria, L.; Stará, Irena G.; Starý, Ivo; Anger, E.; Shen, C.; Moussa, M. E. S.; Vanthuyne, N.; Crassous, J.; Rizzo, A.; Hernández, F. E.

2015-01-01

Roč. 5, č. 23 (2015), s. 17429-17437 ISSN 2046-2069 Institutional support: RVO:61388963 Keywords : [6]helicene * two photon absorption * two photon CD Subject RIV: CC - Organic Chemistry Impact factor: 3.289, year: 2015

Two-photon excited fluorescence emission from hemoglobin

Science.gov (United States)

Sun, Qiqi; Zeng, Yan; Zhang, Wei; Zheng, Wei; Luo, Yi; Qu, Jianan Y.

2015-03-01

Hemoglobin, one of the most important proteins in blood, is responsible for oxygen transportation in almost all vertebrates. Recently, we discovered two-photon excited hemoglobin fluorescence and achieved label-free microvascular imaging based on the hemoglobin fluorescence. However, the mechanism of its fluorescence emission still remains unknown. In this work, we studied the two-photon excited fluorescence properties of the hemoglobin subunits, heme/hemin (iron (II)/(III) protoporphyrin IX) and globin. We first studied the properties of heme and the similar spectral and temporal characteristics of heme and hemoglobin fluorescence provide strong evidence that heme is the fluorophore in hemoglobin. Then we studied the fluorescence properties of hemin, globin and methemoglobin, and found that the hemin may have the main effect on the methemoglobin fluorescence and that globin has tryptophan fluorescence like other proteins. Finally, since heme is a centrosymmetric molecule, that the Soret band fluorescence of heme and hemoglobin was not observed in the single photon process in the previous study may be due to the parity selection rule. The discovery of heme two-photon excited fluorescence may open a new window for heme biology research, since heme as a cofactor of hemoprotein has many functions, including chemical catalysis, electron transfer and diatomic gases transportation.

Broadband high-resolution two-photon spectroscopy with laser frequency combs

OpenAIRE

Hipke, Arthur; Meek, Samuel A.; Ideguchi, Takuro; Hänsch, Theodor W.; Picqué, Nathalie

2013-01-01

Two-photon excitation spectroscopy with broad spectral span is demonstrated at Doppler-limited resolution. We describe first Fourier transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb technique. Each transition is uniquely identified by the modulation imparted by the interfering comb excitations. The temporal modulation of the spontaneous two-photon fluorescence is monitored with a single photodetector, and the spectrum is revealed by a...

How a single photon can mediate entanglement between two others

Energy Technology Data Exchange (ETDEWEB)

Lima Bernardo, Bertúlio de, E-mail: bertulio.fisica@gmail.com

2016-10-15

We describe a novel quantum information protocol, which probabilistically entangles two distant photons that have never interacted. Different from the entanglement swapping protocol, which requires two pairs of maximally entangled photons as the input states, as well as a Bell-state measurement (BSM), the present scheme only requires three photons: two to be entangled and another to mediate the correlation, and no BSM, in a process that we call “entanglement mediation”. Furthermore, in analyzing the paths of the photons in our arrangement, we conclude that one of them, the mediator, exchanges information with the two others simultaneously, which seems to be a new quantum-mechanical feature.

Progress on the Level-1 Calorimeter Trigger

CERN Multimedia

Eric Eisenhandler

The Level-1 Calorimeter Trigger (L1Calo) has recently passed a number of major hurdles. The various electronic modules that make up the trigger are either in full production or are about to be, and preparations in the ATLAS pit are well advanced. L1Calo has three main subsystems. The PreProcessor converts analogue calorimeter signals to digital, associates the rather broad trigger pulses with the correct proton-proton bunch crossing, and does a final calibration in transverse energy before sending digital data streams to the two algorithmic trigger processors. The Cluster Processor identifies and counts electrons, photons and taus, and the Jet/Energy-sum Processor looks for jets and also sums missing and total transverse energy. Readout drivers allow the performance of the trigger to be monitored online and offline, and also send region-of-interest information to the Level-2 Trigger. The PreProcessor (Heidelberg) is the L1Calo subsystem with the largest number of electronic modules (124), and most of its fu...

Resonance-enhanced optical forces between coupled photonic crystal slabs.

Science.gov (United States)

Liu, Victor; Povinelli, Michelle; Fan, Shanhui

2009-11-23

The behaviors of lateral and normal optical forces between coupled photonic crystal slabs are analyzed. We show that the optical force is periodic with displacement, resulting in stable and unstable equilibrium positions. Moreover, the forces are strongly enhanced by guided resonances of the coupled slabs. Such enhancement is particularly prominent near dark states of the system, and the enhancement effect is strongly dependent on the types of guided resonances involved. These structures lead to enhancement of light-induced pressure over larger areas, in a configuration that is directly accessible to externally incident, free-space optical beams.

Triggering extreme events at the nanoscale in photonic seas

KAUST Repository

Liu, Changxu; Van Der Wel, Ruben E C; Rotenberg, Nir; Kuipers, Laurens Kobus; Krauss, T. F.; Di Falco, Andrea; Fratalocchi, Andrea

2015-01-01

Hurricanes, tsunamis, rogue waves and tornadoes are rare natural phenomena that embed an exceptionally large amount of energy, which appears and quickly disappears in a probabilistic fashion. This makes them difficult to predict and hard to generate on demand. Here we demonstrate that we can trigger the onset of rare events akin to rogue waves controllably, and systematically use their generation to break the diffraction limit of light propagation. We illustrate this phenomenon in the case of a random field, where energy oscillates among incoherent degrees of freedom. Despite the low energy carried by each wave, we illustrate how to control a mechanism of spontaneous synchronization, which constructively builds up the spectral energy available in the whole bandwidth of the field into giant structures, whose statistics is predictable. The larger the frequency bandwidth of the random field, the larger the amplitude of rare events that are built up by this mechanism. Our system is composed of an integrated optical resonator, realized on a photonic crystal chip. Through near-field imaging experiments, we record confined rogue waves characterized by a spatial localization of 206 nm and with an ultrashort duration of 163 fs at a wavelength of 1.55 μm. Such localized energy patterns are formed in a deterministic dielectric structure that does not require nonlinear properties.

Triggering extreme events at the nanoscale in photonic seas

KAUST Repository

Liu, Changxu

2015-03-09

Hurricanes, tsunamis, rogue waves and tornadoes are rare natural phenomena that embed an exceptionally large amount of energy, which appears and quickly disappears in a probabilistic fashion. This makes them difficult to predict and hard to generate on demand. Here we demonstrate that we can trigger the onset of rare events akin to rogue waves controllably, and systematically use their generation to break the diffraction limit of light propagation. We illustrate this phenomenon in the case of a random field, where energy oscillates among incoherent degrees of freedom. Despite the low energy carried by each wave, we illustrate how to control a mechanism of spontaneous synchronization, which constructively builds up the spectral energy available in the whole bandwidth of the field into giant structures, whose statistics is predictable. The larger the frequency bandwidth of the random field, the larger the amplitude of rare events that are built up by this mechanism. Our system is composed of an integrated optical resonator, realized on a photonic crystal chip. Through near-field imaging experiments, we record confined rogue waves characterized by a spatial localization of 206 nm and with an ultrashort duration of 163 fs at a wavelength of 1.55 μm. Such localized energy patterns are formed in a deterministic dielectric structure that does not require nonlinear properties.

Nucleon Compton Scattering with Two Space-Like Photons

International Nuclear Information System (INIS)

Andrei Afanasev; I. Akushevich; N.P. Merenkov

2002-01-01

We calculate two-photon exchange effects for elastic electron-proton scattering at high momentum transfers. The corresponding nucleon Compton amplitude is defined by two space-like virtual photons that appear to have significant virtualities. We make predictions for (a) a single-spin beam asymmetry, and (b) a single-spin target asymmetry or recoil proton polarization caused by an unpolarized electron beam

Resonant production in two photon collisions

International Nuclear Information System (INIS)

Butler, F.

1988-12-01

Using 220 picobarn/sup /minus/1/ of data collected by the Mark II detector at PEP, we have measured the width of the /eta/' for quasi real photons. The width is separately measured in the three reactions e + e/sup /minus// → e + e/sup /minus///eta/ 0 π + π/sup /minus//; /eta/ 0 → γγ, e + e/sup /minus// → e + e/sup /minus///eta/ 0 π + π/sup /minus//; /eta/ 0 → π + π/sup /minus//(π 0 ,γ) and e + e/sup /minus// → e + e/sup /minus///rho/ 0 γ, giving a statistically weighted average two-photon width of Γ/sub /eta/'→γγ/ = 5. 21+-0.28 keV. As a by-product of the measurement of Γ/sub /eta/'→γγ/ using the decay mode /eta/' → /rho/γ, we also measured a two-photon decay width for the a 2 (1320) of Γ/sub a 2(1320)→γγ/ = 1.17+-0. 15+-0.25 keV. 47 refs., 50 figs., 8 tabs

Folate receptor targeting silica nanoparticle probe for two-photon fluorescence bioimaging

Science.gov (United States)

Wang, Xuhua; Yao, Sheng; Ahn, Hyo-Yang; Zhang, Yuanwei; Bondar, Mykhailo V.; Torres, Joseph A.; Belfield, Kevin D.

2010-01-01

Narrow dispersity organically modified silica nanoparticles (SiNPs), diameter ~30 nm, entrapping a hydrophobic two-photon absorbing fluorenyl dye, were synthesized by hydrolysis of triethoxyvinylsilane and (3-aminopropyl)triethoxysilane in the nonpolar core of Aerosol-OT micelles. The surface of the SiNPs were functionalized with folic acid, to specifically deliver the probe to folate receptor (FR) over-expressing Hela cells, making these folate two-photon dye-doped SiNPs potential candidates as probes for two-photon fluorescence microscopy (2PFM) bioimaging. In vitro studies using FR over-expressing Hela cells and low FR expressing MG63 cells demonstrated specific cellular uptake of the functionalized nanoparticles. One-photon fluorescence microscopy (1PFM) imaging, 2PFM imaging, and two-photon fluorescence lifetime microscopy (2P-FLIM) imaging of Hela cells incubated with folate-modified two-photon dye-doped SiNPs were demonstrated. PMID:21258480

Two-Photon Absorbing Molecules as Potential Materials for 3D Optical Memory

Directory of Open Access Journals (Sweden)

Kazuya Ogawa

2014-01-01

Full Text Available In this review, recent advances in two-photon absorbing photochromic molecules, as potential materials for 3D optical memory, are presented. The investigations introduced in this review indicate that 3D data storage processing at the molecular level is possible. As 3D memory using two-photon absorption allows advantages over existing systems, the use of two-photon absorbing photochromic molecules is preferable. Although there are some photochromic molecules with good properties for memory, in most cases, the two-photon absorption efficiency is not high. Photochromic molecules with high two-photon absorption efficiency are desired. Recently, molecules having much larger two-photon absorption cross sections over 10,000 GM (GM= 10−50 cm4 s molecule−1 photon−1 have been discovered and are expected to open the way to realize two-photon absorption 3D data storage.

Effect of loss on slow-light enhanced absorption in liquid-infiltrated photonic crystals

DEFF Research Database (Denmark)

Pedersen, Jesper Goor; Xiao, Sanshui; Mortensen, Asger

2008-01-01

We study slow-light enhancement of absorption measurements in photonic crystals composed of lossy dielectrics. We find that the material loss has an unexpected limited drawback and may even increase the bandwidth for low-index contrast systems.......We study slow-light enhancement of absorption measurements in photonic crystals composed of lossy dielectrics. We find that the material loss has an unexpected limited drawback and may even increase the bandwidth for low-index contrast systems....

One Photon Can Simultaneously Excite Two or More Atoms.

Science.gov (United States)

Garziano, Luigi; Macrì, Vincenzo; Stassi, Roberto; Di Stefano, Omar; Nori, Franco; Savasta, Salvatore

2016-07-22

We consider two separate atoms interacting with a single-mode optical or microwave resonator. When the frequency of the resonator field is twice the atomic transition frequency, we show that there exists a resonant coupling between one photon and two atoms, via intermediate virtual states connected by counterrotating processes. If the resonator is prepared in its one-photon state, the photon can be jointly absorbed by the two atoms in their ground state which will both reach their excited state with a probability close to one. Like ordinary quantum Rabi oscillations, this process is coherent and reversible, so that two atoms in their excited state will undergo a downward transition jointly emitting a single cavity photon. This joint absorption and emission process can also occur with three atoms. The parameters used to investigate this process correspond to experimentally demonstrated values in circuit quantum electrodynamics systems.

Dynamical modeling of pulsed two-photon interference

International Nuclear Information System (INIS)

Fischer, Kevin A; Lagoudakis, Konstantinos G; Vučković, Jelena; Müller, Kai

2016-01-01

Single-photon sources are at the heart of quantum-optical networks, with their uniquely quantum emission and phenomenon of two-photon interference allowing for the generation and transfer of nonclassical states. Although a few analytical methods have been briefly investigated for describing pulsed single-photon sources, these methods apply only to either perfectly ideal or at least extremely idealized sources. Here, we present the first complete picture of pulsed single-photon sources by elaborating how to numerically and fully characterize non-ideal single-photon sources operating in a pulsed regime. In order to achieve this result, we make the connection between quantum Monte-Carlo simulations, experimental characterizations, and an extended form of the quantum regression theorem. We elaborate on how an ideal pulsed single-photon source is connected to its photocount distribution and its measured degree of second- and first-order optical coherence. By doing so, we provide a description of the relationship between instantaneous source correlations and the typical experimental interferometers (Hanbury-Brown and Twiss, Hong–Ou–Mandel, and Mach–Zehnder) used to characterize such sources. Then, we use these techniques to explore several prototypical quantum systems and their non-ideal behaviors. As an example numerical result, we show that for the most popular single-photon source—a resonantly excited two-level system—its error probability is directly related to its excitation pulse length. We believe that the intuition gained from these representative systems and characters can be used to interpret future results with more complicated source Hamiltonians and behaviors. Finally, we have thoroughly documented our simulation methods with contributions to the Quantum Optics Toolbox in Python in order to make our work easily accessible to other scientists and engineers. (paper)

Two-photon couplings of quarkonia with arbitrary JPC

International Nuclear Information System (INIS)

Barnes, T.; Tennessee Univ., Knoxville, TN

1992-01-01

We present theoretical results for the two-photon widths of relativistic quarkonium states with arbitrary angular momenta. These relativistic formulas are required to obtain reasonable agreement with the absolute scale of quarkonium decay rates to two photons, and have previously only been derived for spin-singlet q bar q states. We also evaluate these formulas numerically for ell ≤3 q = u, d states in a Coulomb-plus-linear q bar q potential model. Light-quark higher-ell and radially-excited q bar q states should be observable experimentally, as their two-photon widths are typically found to be ∼1 KeV. The radially-excited 1 S 0 higher-mass quarkonium states such as c bar c and b bar b should also be observable in γγ, but orbitally-excited c bar c states with ell>1 and b bar b states with ell>0 are expected to have very small two-photon widths. The helicity structure of the higher-ell q bar q couplings is predicted to be nontrivial, with both λ=0 and λ=2γγ final states contributing significantly; these results may be useful as signatures for q bar q states

A Two-Step Approach for Analytical Optimal Hedging with Two Triggers

Directory of Open Access Journals (Sweden)

Tiesong Hu

2016-02-01

Full Text Available Hedging is widely used to mitigate severe water shortages in the operation of reservoirs during droughts. Rationing is usually instituted with one hedging policy, which is based only on one trigger, i.e., initial storage level or current water availability. It may perform poorly in balancing the benefits of a release during the current period versus those of carryover storage during future droughts. This study proposes a novel hedging rule to improve the efficiency of a reservoir operated to supply water, in which, based on two triggers, hedging is initiated with three different hedging sub-rules through a two-step approach. In the first step, the sub-rule is triggered based on the relationship between the initial reservoir storage level and the level of the target rule curve or the firm rule curve at the end of the current period. This step is mainly concerned with increasing the water level or not in the current period. Hedging is then triggered under the sub-rule based on current water availability in the second step, in which the trigger implicitly considers both initial and ending reservoir storage levels in the current period. Moreover, the amount of hedging is analytically derived based on the Karush–Kuhn–Tucker (KKT conditions. In addition, the hedging parameters are optimized using the improved particle swarm optimization (IPSO algorithm coupled with a rule-based simulation. A single water-supply reservoir located in Hubei Province in central China is selected as a case study. The operation results show that the proposed rule is reasonable and significantly improves the reservoir operation performance for both long-term and critical periods relative to other operation policies, such as the standard operating policy (SOP and the most commonly used hedging rules.

Numerical study on characteristic of two-dimensional metal/dielectric photonic crystals

International Nuclear Information System (INIS)

Zong Yi-Xin; Xia Jian-Bai; Wu Hai-Bin

2017-01-01

An improved plan-wave expansion method is adopted to theoretically study the photonic band diagrams of two-dimensional (2D) metal/dielectric photonic crystals. Based on the photonic band structures, the dependence of flat bands and photonic bandgaps on two parameters (dielectric constant and filling factor) are investigated for two types of 2D metal/dielectric (M/D) photonic crystals, hole and cylinder photonic crystals. The simulation results show that band structures are affected greatly by these two parameters. Flat bands and bandgaps can be easily obtained by tuning these parameters and the bandgap width may reach to the maximum at certain parameters. It is worth noting that the hole-type photonic crystals show more bandgaps than the corresponding cylinder ones, and the frequency ranges of bandgaps also depend strongly on these parameters. Besides, the photonic crystals containing metallic medium can obtain more modulation of photonic bands, band gaps, and large effective refractive index, etc. than the dielectric/dielectric ones. According to the numerical results, the needs of optical devices for flat bands and bandgaps can be met by selecting the suitable geometry and material parameters. (paper)

Cross two photon absorption in a silicon photonic crystal waveguide fiber taper coupler with a physical junction

Energy Technology Data Exchange (ETDEWEB)

Sarkissian, Raymond, E-mail: RaymondSark@gmail.com; O' Brien, John [Electrophysics department, University of Southern California, Los Angeles, California 90089 (United States)

2015-01-21

Cross two photon absorption in silicon is characterized using a tapered fiber photonic crystal silicon waveguide coupler. There is a physical junction between the tapered fiber and the waveguide constituting a stand-alone device. This device is used to obtain the spectrum for cross two photon absorption coefficient per unit volume of interaction between photons of nondegenerate energy. The corresponding Kerr coefficient per unit volume of interaction is also experimentally extracted. The thermal resistance of the device is also experimentally determined and the response time of the device is estimated for on-chip all-optical signal processing and data transfer between optical signals of different photon energies.

The ATLAS Level-1 Calorimeter Trigger

International Nuclear Information System (INIS)

Achenbach, R; Andrei, V; Adragna, P; Apostologlou, P; Barnett, B M; Brawn, I P; Davis, A O; Edwards, J P; Asman, B; Bohm, C; Ay, C; Bauss, B; Bendel, M; Dahlhoff, A; Eckweiler, S; Booth, J R A; Thomas, P Bright; Charlton, D G; Collins, N J; Curtis, C J

2008-01-01

The ATLAS Level-1 Calorimeter Trigger uses reduced-granularity information from all the ATLAS calorimeters to search for high transverse-energy electrons, photons, τ leptons and jets, as well as high missing and total transverse energy. The calorimeter trigger electronics has a fixed latency of about 1 μs, using programmable custom-built digital electronics. This paper describes the Calorimeter Trigger hardware, as installed in the ATLAS electronics cavern

The ATLAS Level-1 Calorimeter Trigger

Energy Technology Data Exchange (ETDEWEB)

Achenbach, R; Andrei, V [Kirchhoff-Institut fuer Physik, University of Heidelberg, D-69120 Heidelberg (Germany); Adragna, P [Physics Department, Queen Mary, University of London, London E1 4NS (United Kingdom); Apostologlou, P; Barnett, B M; Brawn, I P; Davis, A O; Edwards, J P [STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX (United Kingdom); Asman, B; Bohm, C [Fysikum, Stockholm University, SE-106 91 Stockholm (Sweden); Ay, C; Bauss, B; Bendel, M; Dahlhoff, A; Eckweiler, S [Institut fuer Physik, University of Mainz, D-55099 Mainz (Germany); Booth, J R A; Thomas, P Bright; Charlton, D G; Collins, N J; Curtis, C J [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)], E-mail: e.eisenhandler@qmul.ac.uk (and others)

2008-03-15

The ATLAS Level-1 Calorimeter Trigger uses reduced-granularity information from all the ATLAS calorimeters to search for high transverse-energy electrons, photons, {tau} leptons and jets, as well as high missing and total transverse energy. The calorimeter trigger electronics has a fixed latency of about 1 {mu}s, using programmable custom-built digital electronics. This paper describes the Calorimeter Trigger hardware, as installed in the ATLAS electronics cavern.

Scanless two-photon excitation of channelrhodopsin-2

DEFF Research Database (Denmark)

Papagiakoumou, E.; Anselmi, F.; Bègue, A.

2010-01-01

developed a method that combines generalized phase contrast with temporal focusing (TF-GPC) to shape two-photon excitation for this purpose. The illumination patterns are generated automatically from fluorescence images of neurons and shaped to cover the cell body or dendrites, or distributed groups...... of cells. The TF-GPC two-photon excitation patterns generated large photocurrents in Channelrhodopsin-2–expressing cultured cells and neurons and in mouse acute cortical slices. The amplitudes of the photocurrents can be precisely modulated by controlling the size and shape of the excitation volume and...

Space-time description of the two-photon decay

International Nuclear Information System (INIS)

Hrasko, P.

1981-09-01

The time correlation of photons in a two-photon decay is shown to depend on the instantaneous nature of the wave-function collapse in an essential way so the latter hypothesis can be verified by the experimental study of these correlations. (author)

Frequency dependence of coherently amplified two-photon emission from hydrogen molecules

Science.gov (United States)

Hara, Hideaki; Miyamoto, Yuki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

2017-12-01

We investigate how the efficiency of coherently amplified two-photon emission depends on the frequency of one of the two emitted photons, namely the signal photon. This is done over the wavelength range of 5.048-10.21 μ m by using the vibrational transition of parahydrogen. The efficiency increases with the frequency of the signal photon. Considering experimental errors, our results are consistent with the theoretical prediction for the present experimental conditions. This study is an experimental demonstration of the frequency dependence of coherently amplified two-photon emission, and also presents its potential as a light source.

Optimisation of the level-1 calorimeter trigger at ATLAS for Run II

Energy Technology Data Exchange (ETDEWEB)

Suchek, Stanislav [Kirchhoff-Institute for Physics, Im Neuenheimer Feld 227, 69120 Heidelberg (Germany); Collaboration: ATLAS-Collaboration

2015-07-01

The Level-1 Calorimeter Trigger (L1Calo) is a central part of the ATLAS Level-1 Trigger system, designed to identify jet, electron, photon, and hadronic tau candidates, and to measure their transverse energies, as well total transverse energy and missing transverse energy. The optimisation of the jet energy resolution is an important part of the L1Calo upgrade for Run II. A Look-Up Table (LUT) is used to translate the electronic signal from each trigger tower to its transverse energy. By optimising the LUT calibration we can achieve better jet energy resolution and better performance of the jet transverse energy triggers, which are vital for many physics analyses. In addition, the improved energy calibration leads to significant improvements of the missing transverse energy resolution. A new Multi-Chip Module (MCM), as a part of the L1Calo upgrade, provides two separate LUTs for jets and electrons/photons/taus, allowing to optimise jet transverse energy and missing transverse energy separately from the electromagnetic objects. The optimisation is validated using jet transverse energy and missing transverse energy triggers turn-on curves and rates.

Manipulation of a two-photon pump in superconductor - semiconductor heterostructures

Science.gov (United States)

Orth, Peter P.; Baireuther, Paul; Vekhter, Ilya; Schmalian, Joerg

2014-03-01

We investigate the photon statistics, entanglement and squeezing of a pn-junction sandwiched between two superconducting leads, and show that such an electrically-driven photon pump generates correlated and entangled pairs of photons. In particular, we demonstrate that the squeezing of the fluctuations in the quadrature amplitudes of the emitted light can be manipulated by changing the relative phase of the order parameters of the superconductors. This reveals how macroscopic coherence of the superconducting state can be used to tailor the properties of a two-photon state.

Probing two-photon exchange with OLYMPUS

International Nuclear Information System (INIS)

Kohl, M.

2014-01-01

Two-photon exchange is believed to be responsible for the discrepancies in the proton electric to magnetic form factor ratio found with the Rosenbluth and polarization transfer methods. If this explanation is correct, one expects significant differences in the lepton-proton cross sections between positrons and electrons. The OLYMPUS experiment at DESY in Hamburg, Germany was designed to measure the ratio of unpolarized positron-proton and electron-proton elastic scattering cross sections over a wide kinematic range with high precision, in order to quantify the effect of two-photon exchange. The experiment used intense beams of electrons and positrons stored in the DORIS ring at 2.0 GeV interacting with an internal windowless hydrogen gas target. The current status of OLYMPUS will be discussed. (authors)

Non-scanning fiber-optic near-infrared beam led to two-photon optogenetic stimulation in-vivo.

Directory of Open Access Journals (Sweden)

Kamal R Dhakal

Full Text Available Stimulation of specific neurons expressing opsins in a targeted region to manipulate brain function has proved to be a powerful tool in neuroscience. However, the use of visible light for optogenetic stimulation is invasive due to low penetration depth and tissue damage owing to larger absorption and scattering. Here, we report, for the first time, in-depth non-scanning fiber-optic two-photon optogenetic stimulation (FO-TPOS of neurons in-vivo in transgenic mouse models. In order to optimize the deep-brain stimulation strategy, we characterized two-photon activation efficacy at different near-infrared laser parameters. The significantly-enhanced in-depth stimulation efficiency of FO-TPOS as compared to conventional single-photon beam was demonstrated both by experiments and Monte Carlo simulation. The non-scanning FO-TPOS technology will lead to better understanding of the in-vivo neural circuitry because this technology permits more precise and less invasive anatomical delivery of stimulation.

Novel triphenylamine-cored two-photon absorbing dyes for labeling of biomolecules

International Nuclear Information System (INIS)

Xiao Haibo; Mei Chong; Wang Yaochuan; Li, Hui; Qian Shixiong; Yin Hongyao; Xu Zhisong

2011-01-01

Highlights: → Two novel triphenylamine-cored chromophores were synthesized. → These two dyes have sizable two-photon absorption cross-section at 800 nm. → They possess reasonable water solubility and are suitable as labels in aqueous biological environments. → These dyes have strong chelating ability. → They display a large set of reactivity for coupling to biomolecules. - Abstract: Two novel, V-shaped and Y-shaped dipicolinate derivatives branched from triphenylamine, {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinyl]}-N-phenyl-N-{4- [(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinylphenyl]}aniline (1) and {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl) vinyl]}-N,N-bis {4-[(E)-2-(2,6-dimethoxycarbonyl pyridin-4-yl)vinylphenyl]}aniline (2) were synthesized. These compounds were designed for large two-photon absorption and in particular for labeling of biomolecules. Their linear absorption, fluorescence properties and their two-photon absorption properties as well as two-photon fluorescence cell imaging were examined. When excited at 800 nm, the two-photon absorption cross-section values of chromophores 1 and 2 in THF were 208 GM, 376 GM, respectively. These two-photon absorbing dyes possess reasonable water solubility, strong chelating ability and display a large set of reactivity for coupling to biomolecules, which are apparently due to the two methoxycarbonyl groups in pyridine ring. This work suggests that chromophores 1 and 2 are promising labels potentially applicable for the tracking of biomolecules using two-photon scanning microscopy.

Numerical study on characteristic of two-dimensional metal/dielectric photonic crystals

Science.gov (United States)

Zong, Yi-Xin; Xia, Jian-Bai; Wu, Hai-Bin

2017-04-01

An improved plan-wave expansion method is adopted to theoretically study the photonic band diagrams of two-dimensional (2D) metal/dielectric photonic crystals. Based on the photonic band structures, the dependence of flat bands and photonic bandgaps on two parameters (dielectric constant and filling factor) are investigated for two types of 2D metal/dielectric (M/D) photonic crystals, hole and cylinder photonic crystals. The simulation results show that band structures are affected greatly by these two parameters. Flat bands and bandgaps can be easily obtained by tuning these parameters and the bandgap width may reach to the maximum at certain parameters. It is worth noting that the hole-type photonic crystals show more bandgaps than the corresponding cylinder ones, and the frequency ranges of bandgaps also depend strongly on these parameters. Besides, the photonic crystals containing metallic medium can obtain more modulation of photonic bands, band gaps, and large effective refractive index, etc. than the dielectric/dielectric ones. According to the numerical results, the needs of optical devices for flat bands and bandgaps can be met by selecting the suitable geometry and material parameters. Project supported by the National Basic Research Program of China (Grant No. 2011CB922200) and the National Natural Science Foundation of China (Grant No. 605210010).

Imaging immune response of skin mast cells in vivo with two-photon microscopy

Science.gov (United States)

Li, Chunqiang; Pastila, Riikka K.; Lin, Charles P.

2012-02-01

Intravital multiphoton microscopy has provided insightful information of the dynamic process of immune cells in vivo. However, the use of exogenous labeling agents limits its applications. There is no method to perform functional imaging of mast cells, a population of innate tissue-resident immune cells. Mast cells are widely recognized as the effector cells in allergy. Recently their roles as immunoregulatory cells in certain innate and adaptive immune responses are being actively investigated. Here we report in vivo mouse skin mast cells imaging with two-photon microscopy using endogenous tryptophan as the fluorophore. We studied the following processes. 1) Mast cells degranulation, the first step in the mast cell activation process in which the granules are released into peripheral tissue to trigger downstream reactions. 2) Mast cell reconstitution, a procedure commonly used to study mast cells functioning by comparing the data from wild type mice, mast cell-deficient mice, and mast-cell deficient mice reconstituted with bone marrow-derived mast cells (BMMCs). Imaging the BMMCs engraftment in tissue reveals the mast cells development and the efficiency of BMMCs reconstitution. We observed the reconstitution process for 6 weeks in the ear skin of mast cell-deficient Kit wsh/ w-sh mice by two-photon imaging. Our finding is the first instance of imaging mast cells in vivo with endogenous contrast.

Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus

International Nuclear Information System (INIS)

Song, Minsoo; Yoon, Tai Hyun

2013-01-01

We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s 2 1 S 0 ↔ 6s7s 1 S 0 ) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm 3 and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s 1 S 0 state via the intercombination 6s6p 3 P 1 state with a high signal-to-noise ratio even at the temperature of 340 °C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle.

Atomic Evolution and Entanglement of Two Qubits in Photon Superfluid

Science.gov (United States)

Yin, Miao; Zhang, Xiongfeng; Deng, Yunlong; Deng, Huaqiu

2018-03-01

By using reservoir theory, we investigate the evolution of an atom placed in photon superfluid and study the entanglement properties of two qubits interacting with photon superfluid. It is found that the atomic decay rate in photon superfluid changes periodically with position of the atom and the decay rate can be inhibited compared to that in usual electromagnetic environment without photon superfluid. It is also found that when two atoms are separately immersed in their own local photon-superfluid reservoir, the entanglement sudden death or birth occurs or not only depends on the initial state of the qubits. What is more, we find a possible case that the concurrence between two qubits can remain a constant value by choosing proper values of parameters of the system, which may provide a new way to preserve quantum entanglement.

Photon activation therapy with 127I-deoxyuridine: measurement of dose enhancement in cultured mammalian cells

International Nuclear Information System (INIS)

Fairchild, R.G.; Laster, B.H.; Commerford, S.L.; Furcinitti, P.S.; Sylvester, B.; Gabel, D.; Popenoe, E.; Foster, S.

1985-01-01

A technique for radiation enhancement of conventional photon radiotherapy is outlined which has been called photon activation therapy (PAT) (6). High linear energy transfer (LET) radiations in the form of Auger electron distributions are generated by photons of appropriate energies, through photon activation of stable iodine incorporated as an analog of thymidine (Tyd) in DNA. Of the several halogenated deoxyribonucleosides evaluated, iodinated deoxyuridine (IdUrd) has been chosen as the only Tyd analog providing effective photon activation. This mechanism is combined with radiation sensitization produced by IdUrd to produce an overall radiation enhancement. Calculations show that at 5% replacement (IdUrd for Tyd) therapeutic (TG) will vary from ∼2 (single acute dose) to ∼17 (low dose rates associated with permanent implant brachytherapy). Parameters used in the calculation of TG have been evaluated in cell culture; dose enhancements obtained with x-rays (including photon activation) were found to be significantly higher than values measured with γ-rays (no photon activation). Comparison is made between theoretical and measured values. Because of the evident lack of repair of damage produced by both sensitization and photon activation, significant gains are expected to be realized following protracted irradiations. Exchanges (IdUrd for Tyd) for 105 have been obtained in vivo (murine tumors). The authors believe that the application of PAT would be most advantageous in the treatment of brain tumors (grade IV astrocytomas) with implanted 145 Sm sources

Double-Tag Events in Two-Photon Collisions at LEP

CERN Document Server

Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Buijs, A.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; van Dierendonck, D.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duinker, P.; Echenard, B.; Eline, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Ewers, A.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Krenz, W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Lubelsmeyer, K.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mangeol, D.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Niessen, T.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Palomares, C.; Pandoulas, D.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.O.; Prokofiev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, M.A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Roux, B.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Sanders, M.P.; Schafer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schmitz, D.; Schopper, H.; Schotanus, D.J.; Schwering, G.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Siedenburg, T.; Son, D.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wallraff, W.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zilizi, G.; Zimmermann, B.; Zoller, M.

2002-01-01

Double-tag events in two-photon collisions are studied using the L3 detector at LEP centre-of-mass energies from root(s)=189 GeV to 209 GeV. The cross sections of the e+e- -> e+e- hadrons and gamma*gamma* -> hadrons processes are measured as a function of the photon virtualities, Q2_1 and Q2_2, of the two-photon mass, W_gammagamma, and of the variable Y=ln(W2_gammagamma/(Q_1Q_2)), for an average photon virtuality = 16 GeV2. The results are in agreement with next-to-leading order calculations for the process gamma*gamma* -> q qbar in the interval 2 <= Y <= 5. An excess is observed in the interval 5 < Y <= 7, corresponding to W_gammagamma greater than 40 GeV . This may be interpreted as a sign of resolved photon QCD processes or the onset of BFKL phenomena.

Distribution of quantum information between an atom and two photons

International Nuclear Information System (INIS)

Weber, Bernhard

2008-01-01

The construction of networks consisting of optically interconnected processing units is a promising way to scale up quantum information processing systems. To store quantum information, single trapped atoms are among the most proven candidates. By placing them in high finesse optical resonators, a bidirectional information exchange between the atoms and photons becomes possible with, in principle, unit efficiency. Such an interface between stationary and ying qubits constitutes a possible node of a future quantum network. The results presented in this thesis demonstrate the prospects of a quantum interface consisting of a single atom trapped within the mode of a high-finesse optical cavity. In a two-step process, we distribute entanglement between the stored atom and two subsequently emitted single photons. The long atom trapping times achieved in the system together with the high photon collection efficiency of the cavity make the applied protocol in principle deterministic, allowing for the creation of an entangled state at the push of a button. Running the protocol on this quasi-stationary quantum interface, the internal state of the atom is entangled with the polarization state of a single emitted photon. The entanglement is generated by driving a vacuum-stimulated Raman adiabatic passage between states of the coupled atom-cavity system. In a second process, the atomic part of the entangled state is mapped onto a second emitted photon using a similar technique and resulting in a polarization-entangled two-photon state. To verify and characterize the photon-photon entanglement, we measured a violation of a Bell inequality and performed a full quantum state tomography. The results prove the prior atom-photon entanglement and demonstrate a quantum information transfer between the atom and the two emitted photons. This reflects the advantages of a high-finesse cavity as a quantum interface in future quantum networks. (orig.)

Distribution of quantum information between an atom and two photons

Energy Technology Data Exchange (ETDEWEB)

Weber, Bernhard

2008-11-03

The construction of networks consisting of optically interconnected processing units is a promising way to scale up quantum information processing systems. To store quantum information, single trapped atoms are among the most proven candidates. By placing them in high finesse optical resonators, a bidirectional information exchange between the atoms and photons becomes possible with, in principle, unit efficiency. Such an interface between stationary and ying qubits constitutes a possible node of a future quantum network. The results presented in this thesis demonstrate the prospects of a quantum interface consisting of a single atom trapped within the mode of a high-finesse optical cavity. In a two-step process, we distribute entanglement between the stored atom and two subsequently emitted single photons. The long atom trapping times achieved in the system together with the high photon collection efficiency of the cavity make the applied protocol in principle deterministic, allowing for the creation of an entangled state at the push of a button. Running the protocol on this quasi-stationary quantum interface, the internal state of the atom is entangled with the polarization state of a single emitted photon. The entanglement is generated by driving a vacuum-stimulated Raman adiabatic passage between states of the coupled atom-cavity system. In a second process, the atomic part of the entangled state is mapped onto a second emitted photon using a similar technique and resulting in a polarization-entangled two-photon state. To verify and characterize the photon-photon entanglement, we measured a violation of a Bell inequality and performed a full quantum state tomography. The results prove the prior atom-photon entanglement and demonstrate a quantum information transfer between the atom and the two emitted photons. This reflects the advantages of a high-finesse cavity as a quantum interface in future quantum networks. (orig.)

Two-photon induced fluorescence and other optical effects in irradiated and doped fused silica

International Nuclear Information System (INIS)

Kramer, S.D.

1986-07-01

The objective of this program was to assess and identify irradiation techniques which could be used to modify the optical charactistics of doped fused silica. Primary emphasis was placed on determining if gamma ray or neutron bombardment of the glass would enhance certain Raman and nonlinear optical effects. In particular, the effect of irradiation on optical two photon induced fluorescence was studied in detail. The maximum radiation exposures used were 10 6 rads (Si) of gamma rays and neutron fluences of 1 x 10 14 neutrons/cm 2 . The optical measurements were made at room temperature between one and four months after irradiation. The maximum input light intensity was 10 9 watts/cm 2 at a near infrared (1.06 μ) input wavelength which was chosen to lie in a transparent spectral region of the glass. Under these experimental conditions a careful search revealed no detectable two-photon induced fluorescence in the region from 550 to 900 nm. The upper limit for the photon efficiency of this process was determined to be less than 1 x 10 -10 %. 89 refs., 12 figs

Virtual-pion and two-photon production in pp scattering

International Nuclear Information System (INIS)

Scholten, O.; Korchin, A.Yu.

2002-01-01

Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contributions. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

Topological Valley Transport in Two-dimensional Honeycomb Photonic Crystals.

Science.gov (United States)

Yang, Yuting; Jiang, Hua; Hang, Zhi Hong

2018-01-25

Two-dimensional photonic crystals, in analogy to AB/BA stacking bilayer graphene in electronic system, are studied. Inequivalent valleys in the momentum space for photons can be manipulated by simply engineering diameters of cylinders in a honeycomb lattice. The inequivalent valleys in photonic crystal are selectively excited by a designed optical chiral source and bulk valley polarizations are visualized. Unidirectional valley interface states are proved to exist on a domain wall connecting two photonic crystals with different valley Chern numbers. With the similar optical vortex index, interface states can couple with bulk valley polarizations and thus valley filter and valley coupler can be designed. Our simple dielectric PC scheme can help to exploit the valley degree of freedom for future optical devices.

Quantum-correlated two-photon transitions to excitons in semiconductor quantum wells.

Science.gov (United States)

Salazar, L J; Guzmán, D A; Rodríguez, F J; Quiroga, L

2012-02-13

The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers.

Two-photon decay of K-shell vacancy states in heavy atoms

International Nuclear Information System (INIS)

Ilakovac, K.; Uroic, M.; Majer, M.; Pasic, S.; Vukovic, B.

2006-01-01

Two-photon decay has been extensively studied in atomic, nuclear and particle physics since the 1930s when the problem of stability of the 2s state of the hydrogen atom emerged. Since then, many theoretical and experimental investigations have been made on hydrogen and one-electron (H-like) ions and on helium and two-electron (He-like) ions. The work on two-photon decay in many-electron systems involving inner shells started about 30 years ago and, in the meantime, two-photon decay of the K-shell vacancy state has been the subject of many theoretical and experimental studies. Experimental results have been obtained for 2s->1s and higher-state electron ->1s two-photon transitions in molybdenum, and for 2s -> 1s, 3s -> 1s, 3d -> 1s and 4sd -> 1s two-photon transitions in silver, xenon, hafnium and mercury. Nonrelativistic and relativistic calculations of the processes have been made. The relativistic calculations for transitions in molybdenum, silver and xenon atoms are in a reasonable agreement with the experimental results, but some problems remain to be solved. A review of investigations of two-photon transitions in atomic systems is presented

Time-resolved measurement of the quantum states of photons using two-photon interference with short-time reference pulses

International Nuclear Information System (INIS)

Ren Changliang; Hofmann, Holger F.

2011-01-01

To fully utilize the energy-time degree of freedom of photons for optical quantum-information processes, it is necessary to control and characterize the temporal quantum states of the photons at extremely short time scales. For measurements of the temporal coherence of the quantum states beyond the time resolution of available detectors, two-photon interference with a photon in a short-time reference pulse may be a viable alternative. In this paper, we derive the temporal measurement operators for the bunching statistics of a single-photon input state with a photon from a weak coherent reference pulse. It is shown that the effects of the pulse shape of the reference pulse can be expressed in terms of a spectral filter selecting the bandwidth within which the measurement can be treated as an ideal projection on eigenstates of time. For full quantum tomography, temporal coherence can be determined by using superpositions of reference pulses at two different times. Moreover, energy-time entanglement can be evaluated based on the two-by-two entanglement observed in the coherences between pairs of detection times.

High contrast two-photon imaging of fingermarks

Science.gov (United States)

Stoltzfus, Caleb R.; Rebane, Aleksander

2016-04-01

Optically-acquired fingermarks are widely used as evidence across law enforcement agencies as well as in the courts of law. A common technique for visualizing latent fingermarks on nonporous surfaces consists of cyanoacrylate fuming of the fingerprint material, followed by impregnation with a fluorescent dye, which under ultra violet (UV) illumination makes the fingermarks visible and thus accessible for digital recording. However, there exist critical circumstances, when the image quality is compromised due to high background scattering, high auto-fluorescence of the substrate material, or other detrimental photo-physical and photo-chemical effects such as light-induced damage to the sample. Here we present a novel near-infrared (NIR), two-photon induced fluorescence imaging modality, which significantly enhances the quality of the fingermark images, especially when obtained from highly reflective and/or scattering surfaces, while at the same time reducing photo-damage to sensitive forensic samples.

Nano-Structures for Optics and Photonics: Optical Strategies for Enhancing

CERN Document Server

Collins, John; Silvestri, Luciano

2015-01-01

The contributions in this volume were presented at a NATO Advanced Study Institute held in Erice, Italy, 4-19 July 2013. Many aspects of important research into nanophotonics, plasmonics, semiconductor materials and devices, instrumentation for bio sensing to name just a few, are covered in depth in this volume.  The growing connection between optics and electronics, due to the increasing important role plaid by semiconductor materials and devices, find their expression in the term photonics, which also reflects the importance of the photon aspect of light in the description of the performance of several optical systems. Nano-structures have unique capabilities that allow the enhanced performance of processes of interest in optical and photonic devices. In particular these structures permit the nanoscale manipulation of photons, electrons and atoms; they represent a very hot topic of research and are relevant to many devices and applications. The various subjects bridge over the disciplines of physics, biolo...

Enhanced light extraction from GaN-based LEDs with a bottom-up assembled photonic crystal

International Nuclear Information System (INIS)

Gong Haibo; Hao Xiaopeng; Wu Yongzhong; Cao Bingqiang; Xia Wei; Xu Xiangang

2011-01-01

Highlights: → Polystyrene (PS) microspheres were employed as a template. → A noninvasive photonic crystal was fabricated on the surface of GaN-based LED. → Periodic arrangement of bowl-like holes served as a photonic crystal with gradually changed fill factors. → The electroluminescence intensity of LED with a photonic crystal was significantly enhanced. - Abstract: Photonic crystal (PhC) structure is an efficient tool for light extraction from light-emitting diodes (LEDs). The fabrication of a large area PhC structure on the light output surface of LEDs often involves sophisticated equipments such as nanoimprint lithography machine. In this study a monolayer of polystyrene (PS) microspheres was employed as a template to fabricate a noninvasive photonic crystal of indium tin oxide (ITO) on the surface of GaN-based LED. PS spheres can help to form periodic arrangement of bowl-like holes, a photonic crystal with gradually changed fill factors. Importantly, the electroluminescence intensity of LED with a photonic crystal was significantly enhanced by 1.5 times compared to that of the conventional one under various forward injection currents.

Enhanced light extraction from GaN-based LEDs with a bottom-up assembled photonic crystal

Energy Technology Data Exchange (ETDEWEB)

Gong Haibo [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); School of Materials Science and Engineering, University of Jinan, Jinan, 250022 (China); Hao Xiaopeng, E-mail: xphao@sdu.edu.cn [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); Wu Yongzhong [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); Cao Bingqiang [School of Materials Science and Engineering, University of Jinan, Jinan, 250022 (China); Xia Wei [Shandong Huaguang Optoelectronics Company, Ltd., Jinan, 250101 (China); Xu Xiangang [State Key Lab of Crystal Materials, Shandong University, Jinan, 250100 (China); Shandong Huaguang Optoelectronics Company, Ltd., Jinan, 250101 (China)

2011-08-15

Highlights: > Polystyrene (PS) microspheres were employed as a template. > A noninvasive photonic crystal was fabricated on the surface of GaN-based LED. > Periodic arrangement of bowl-like holes served as a photonic crystal with gradually changed fill factors. > The electroluminescence intensity of LED with a photonic crystal was significantly enhanced. - Abstract: Photonic crystal (PhC) structure is an efficient tool for light extraction from light-emitting diodes (LEDs). The fabrication of a large area PhC structure on the light output surface of LEDs often involves sophisticated equipments such as nanoimprint lithography machine. In this study a monolayer of polystyrene (PS) microspheres was employed as a template to fabricate a noninvasive photonic crystal of indium tin oxide (ITO) on the surface of GaN-based LED. PS spheres can help to form periodic arrangement of bowl-like holes, a photonic crystal with gradually changed fill factors. Importantly, the electroluminescence intensity of LED with a photonic crystal was significantly enhanced by 1.5 times compared to that of the conventional one under various forward injection currents.

An integrated single- and two-photon non-diffracting light-sheet microscope

Science.gov (United States)

Lau, Sze Cheung; Chiu, Hoi Chun; Zhao, Luwei; Zhao, Teng; Loy, M. M. T.; Du, Shengwang

2018-04-01

We describe a fluorescence optical microscope with both single-photon and two-photon non-diffracting light-sheet excitations for large volume imaging. With a special design to accommodate two different wavelength ranges (visible: 400-700 nm and near infrared: 800-1200 nm), we combine the line-Bessel sheet (LBS, for single-photon excitation) and the scanning Bessel beam (SBB, for two-photon excitation) light sheet together in a single microscope setup. For a transparent thin sample where the scattering can be ignored, the LBS single-photon excitation is the optimal imaging solution. When the light scattering becomes significant for a deep-cell or deep-tissue imaging, we use SBB light-sheet two-photon excitation with a longer wavelength. We achieved nearly identical lateral/axial resolution of about 350/270 nm for both imagings. This integrated light-sheet microscope may have a wide application for live-cell and live-tissue three-dimensional high-speed imaging.

Searching for Dark Photons with the SeaQuest Spectrometer

Science.gov (United States)

Uemura, Sho; SeaQuest Collaboration

2017-09-01

The existence of a dark sector, containing families of particles that do not couple directly to the Standard Model, is motivated as a possible model for dark matter. A ``dark photon'' - a massive vector boson that couples weakly to electric charge - is a common component of dark sector models. The SeaQuest spectrometer at Fermilab is designed to detect dimuon pairs produced by the interaction of a 120 GeV proton beam with a rotating set of thin fixed targets. An iron-filled magnet downstream of the target, 5 meters in length, serves as a beam dump. The SeaQuest spectrometer is sensitive to dark photons that are mostly produced in the beam dump and decay to dimuons, and a SeaQuest search for dark sector particles was approved as Fermilab experiment E1067. As part of E1067, a displaced-vertex trigger was built, installed and commissioned this year. This trigger uses two planes of extruded scintillators to identify dimuons originating far downstream of the target, and is sensitive to dark photons that travel deep inside the beam dump before decaying to dimuons. This trigger will be used to take data parasitically with the primary SeaQuest physics program. In this talk I will present the displaced-vertex trigger and its performance, and projected sensitivity from future running.

Investigation of the two-photon decay following the neutron capture in hydrogen

International Nuclear Information System (INIS)

Wuest, N.

1978-01-01

The continuous two-photon radiation, resulting from thermal neutron capture in hydrogen, has been measured. This reaction can be described in second order perturbation theory and occurs besides the dominating 2223.4 keV single-photon radiation. The theoretical ratio between two-photon and one-photon process is 2.8 10 -7 for the case considered here, so coincidence experiments with extremely high sensitivity have to be performed. In order to exclude systematical errors, three measurements with a different experimental set-up have been performed. Besides the total cross section for the two-photon process, the differential cross section has been studied in one of the experiments as a function of the energy ratio of the two photons. For the branching ratio between the two- and one-photon process an upper limit of 2 x 10 -5 could be obtained. So the hypothesis that the neutron capture state and the deuterium ground state one non-orthogonal, is shown to be false. (orig.) [de

Source of single photons and interferometry with one photon. From the Young's slit experiment to the delayed choice

International Nuclear Information System (INIS)

Jacques, V.

2007-11-01

This manuscript is divided in two independent parts. In the first part, we study the wave-particle duality for a single photon emitted by the triggered photoluminescence of a single NV color center in a diamond nano-crystal. We first present the realization of a single-photon interference experiment using a Fresnel's bi-prism, in a scheme equivalent to the standard Young's double-slit textbook experiment. We then discuss the complementarity between interference and which-path information in this two-path interferometer. We finally describe the experimental realization of Wheeler's delayed-choice Gedanken experiment, which is a fascinating and subtle illustration of wave-particle duality. The second part of the manuscript is devoted to the efficiency improvement of single-photon sources. We first describe the implementation of a new single-photon source based on the photoluminescence of a single nickel-related defect center in diamond. The photophysical properties of such defect make this single-photon source well adapted to open-air quantum cryptography. We finally demonstrate an original method that leads to an improvement of single-molecule photo stability at room temperature. (author)

Radiative corrections to two photon physics

International Nuclear Information System (INIS)

Neervan, W.L. van; Vermaseren, J.A.M.

1983-06-01

The authors develop a method to calculate radiative corrections to two photon reactions of the type e + e - →e + e - X where X is an arbitrary final state. To illustrate this they take the example where X stands for a point-like pseudoscalar. It will be shown that the method is an improvement on the standard way in adding real and virtual photon contributions to the (differential) cross-sections. This makes it possible to compute differential and total cross-sections to a very high precision and with a minimum of computer time which is not possible by using more conventional methods. (Auth.)

Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering

Energy Technology Data Exchange (ETDEWEB)

Seipt, Daniel

2012-12-20

scattering. An enhancement of the two-photon process is found in strong laser pulses as compared to the corresponding weak-field process in perturbative QED.

In vivo two-photon imaging of retina in rabbits and rats.

Science.gov (United States)

Jayabalan, Gopal Swamy; Wu, Yi-Kai; Bille, Josef F; Kim, Samuel; Mao, Xiao Wen; Gimbel, Howard V; Rauser, Michael E; Fan, Joseph T

2018-01-01

The purpose of this study was to evaluate the retina using near-infrared (NIR) two-photon scanning laser ophthalmoscopy. New Zealand white rabbits, albino rats, and brown Norway rats were used in this study. An autofluorescence image of the retina, including the retinal cells and its associated vasculatures was obtained by a real-time scan using the ophthalmoscope. Furthermore, the retinal vessels, nerve fiber layers and the non-pigmented retina were recorded with two-photon fluorescein angiography (FA); and the choroidal vasculatures were recorded using two-photon indocyanine green angiography (ICGA). Two-photon ICGA was achieved by exciting a second singlet state at ∼398 nm. Simultaneous two-photon FA and two-photon ICGA were performed to characterize the retinal and choroidal vessels with a single injection. The minimum laser power threshold required to elicit two-photon fluorescence was determined. The two-photon ophthalmoscope could serve as a promising tool to detect and monitor the disease progression in animal models. Moreover, these high-resolution images of retinal and choroidal vessels can be acquired in a real-time scan with a single light source, requiring no additional filters for FA or ICGA. The combination of FA and ICGA using the two-photon ophthalmoscope will help researchers to characterize the retinal diseases in animal models, and also to classify the types (classic, occult or mixed) of choroidal neovascularization (CNV) in macular degeneration. Furthermore, the prototype can be adapted to image the retina of rodents and rabbits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Two-dimensionally confined topological edge states in photonic crystals

International Nuclear Information System (INIS)

Barik, Sabyasachi; Miyake, Hirokazu; DeGottardi, Wade; Waks, Edo; Hafezi, Mohammad

2016-01-01

We present an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states. The topological properties of the system are controlled by the crystal parameters. An interface between two regions of differing band topologies gives rise to topological edge states confined in a dielectric slab that propagate around sharp corners without backscattering. Three-dimensional finite-difference time-domain calculations show these edges to be confined in the out-of-plane direction by total internal reflection. Such nanoscale photonic crystal architectures could enable strong interactions between photonic edge states and quantum emitters. (paper)

Pion-pair production by two photons

International Nuclear Information System (INIS)

Terazawa, Hidezumi.

1994-07-01

The cross section for pion-pair production by two photons is calculated approximately by using the low energy theorem previously derived from partially-conserved-axial-vector-current hypothesis and current algebra, and found to agree very well with the experimental data recently obtained by the Mark II, TPC/Two-Gamma and CLEO Collaborations. (author)

In-depth study of single photon time resolution for the Philips digital silicon photomultiplier

International Nuclear Information System (INIS)

Liu, Z.; Pizzichemi, M.; Ghezzi, A.; Paganoni, M.; Gundacker, S.; Auffray, E.; Lecoq, P.

2016-01-01

The digital silicon photomultiplier (SiPM) has been commercialised by Philips as an innovative technology compared to analog silicon photomultiplier devices. The Philips digital SiPM, has a pair of time to digital converters (TDCs) connected to 12800 single photon avalanche diodes (SPADs). Detailed measurements were performed to understand the low photon time response of the Philips digital SiPM. The single photon time resolution (SPTR) of every single SPAD in a pixel consisting of 3200 SPADs was measured and an average value of 85 ps full width at half maximum (FWHM) was observed. Each SPAD sends the signal to the TDC with different signal propagation time, resulting in a so called trigger network skew. This distribution of the trigger network skew for a pixel (3200 SPADs) has been measured and a variation of 50 ps FWHM was extracted. The SPTR of the whole pixel is the combination of SPAD jitter, trigger network skew, and the SPAD non-uniformity. The SPTR of a complete pixel was 103 ps FWHM at 3.3 V above breakdown voltage. Further, the effect of the crosstalk at a low photon level has been studied, with the two photon time resolution degrading if the events are a combination of detected (true) photons and crosstalk events. Finally, the time response to multiple photons was investigated.

Azimuthal correlations of high-pT photons and hadrons in Au+Au collisions at STAR

International Nuclear Information System (INIS)

Dietel, T.

2006-01-01

The STAR experiment observed a modification of the azimuthal correlations between a trigger particle and associated particles in central Au+Au collisions, where trigger particles with 4 GeV T trigger T trigger <4 GeV were selected. This thesis studies azimuthal correlations between regions of high energy deposition in the electro-magnetic calorimeter as trigger- and charged tracks as associated particles. The data sample had been enriched by online event selection, allowing for the selection of trigger particles with a transverse energy of more than 10 GeV and associated particles with more than 2, 3 or 4 GeV. The trigger particles are a mixture of photon pairs from the decays of neutral pions and single photons, mainly from photon-jet events, with small contributions from other hadron decays and fragmentation photons. (orig.)

Broadband enhancement of spontaneous emission in a photonic-plasmonic structure

DEFF Research Database (Denmark)

Zhu, Xiaolong; Xie, Fengxian; Shi, Lei

2012-01-01

We demonstrate that a broadband enhancement of spontaneous emission can be achieved within a photonic-plasmonic structure. The structure can strongly modify the spontaneous emission by exciting plasmonic modes. Because of the excited plasmonic modes, an enhancement up to 30 times is observed, lea......, leading to a 4 times broader emission spectrum. The reflectance measurement and the finite-difference time-domain simulation are carried out to support these results....

Two-color ghost interference with photon pairs generated in hot atoms

Directory of Open Access Journals (Sweden)

Dong-Sheng Ding

2012-09-01

Full Text Available We report on an experimental observation of a two-photon ghost interference experiment. A distinguishing feature of our experiment is that the photons are generated via a non-degenerated spontaneous four-wave mixing process in a hot atomic ensemble; therefore the photon has narrow bandwidth. Besides, there is a large difference in frequency between two photons in a pair. Our works may be important to achieve more secure, large transmission capacity long-distance quantum communication.

Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides

DEFF Research Database (Denmark)

Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn

2017-01-01

Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light-matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally...... in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines...

Charm production in two-photon collisions

International Nuclear Information System (INIS)

Linde, F.L.

1988-01-01

The analysis focuses on the production of charmonium resonances η c , χ 0 and χ 2 in two-photon interactions. The measurement of the inclusive production of charged D* mesons is described. 97 refs.; 54 figs.; 15 tabs

Closed form for two-photon free-free transition matrix elements

Energy Technology Data Exchange (ETDEWEB)

Karule, Erna E-mail: karule@latnet.lv

2000-08-01

Two-photon free-free transitions happen in the multiphoton ionization with more than one excess photon and in Bremsstrahlung. Up to now, the configuration space free-free transition amplitudes have not been written in closed form. We propose a modified Coulomb Green's function (CGF) Sturm ian expansion which allows one to obtain expressions for two-photon radial transition matrix elements in the closed form which are easy to continue analytically to calculate free-free transitions in H.

Two-Photon Excitation Microscopy for the Study of Living Cells and Tissues

Science.gov (United States)

Benninger, Richard K.P.; Piston, David W.

2013-01-01

Two-photon excitation microscopy is an alternative to confocal microscopy that provides advantages for three-dimensional and deep tissue imaging. This unit will describe the basic physical principles behind two-photon excitation and discuss the advantages and limitations of its use in laser-scanning microscopy. The principal advantages of two-photon microscopy are reduced phototoxicity, increased imaging depth, and the ability to initiate highly localized photochemistry in thick samples. Practical considerations for the application of two-photon microscopy will then be discussed, including recent technological advances. This unit will conclude with some recent applications of two-photon microscopy that highlight the key advantages over confocal microscopy and the types of experiments which would benefit most from its application. PMID:23728746

Control of one- and two-photon absorption in a four-level atomic system by changing the amplitude and phase of a driving microwave field

International Nuclear Information System (INIS)

Hou, B P; Wang, S J; Yu, W L; Sun, W L

2005-01-01

We consider the one- and two-photon absorption spectra of a four-level Y-type atom with the two highest lying levels driven by a microwave field. We found that in the one-photon absorption case, the microwave field can lead to the probe gain, and the absorption and gain spectral structures depend strongly on the microwave field amplitude. For the two-photon absorption case, the strong microwave field can enhance the absorption. When the microwave field amplitude is reduced to a certain value, the single absorption peak in the two-photon spectrum changes into a structure of two-peak structure with different magnitudes. Moreover, the one- and two-photon absorption spectra can be modulated by the phase of the microwave field which produces a closed-loop configuration. Finally, we use the analytic solutions in terms of dressed-state basis to explain the results from our numerical calculation

Hollow-Core Photonic Crystal Fibers for Surface-Enhanced Raman Scattering Probes

Directory of Open Access Journals (Sweden)

Xuan Yang

2011-01-01

Full Text Available Photonic crystal fiber (PCF sensors based on surface-enhanced Raman scattering (SERS have become increasingly attractive in chemical and biological detections due to the molecular specificity, high sensitivity, and flexibility. In this paper, we review the development of PCF SERS sensors with emphasis on our recent work on SERS sensors utilizing hollow-core photonic crystal fibers (HCPCFs. Specifically, we discuss and compare various HCPCF SERS sensors, including the liquid-filled HCPCF and liquid-core photonic crystal fibers (LCPCFs. We experimentally demonstrate and theoretically analyze the high sensitivity of the HCPCF SERS sensors. Various molecules including Rhodamine B, Rhodamine 6G, human insulin, and tryptophan have been tested to show the excellent performance of these fiber sensors.

Towards Precision Measurement of the 21S0-31D2 Two-Photon Transition in Atomic Helium

Science.gov (United States)

Huang, Yi-Jan; Guan, Yu-Chan; Suen, Te-Hwei; Wang, Li-Bang; Shy, Jow-Tsong

2017-04-01

We intend to accurately measure the frequency for 2S-3D two-photon transition and to deduce the 2S ionization energy to an accuracy below 100 kHz from the theoretical calculation of the 3D state. In this talk, we present a precision measurement of the 21S0 -31D2 two-photon transition in atomic helium at 1009 nm. A master oscillator power amplifier (MOPA) is seeded by an external cavity diode laser (ECDL) is constructed to generate more than 700 mW laser power with TEM00 beam profile at 1009 nm. To observe the two-photon transition, a helium cell is placed inside a power enhancement optical cavity and the helium atoms at 21S metastable level are prepared by a pulsed RF discharge and monitor the 668 nm 31D2 to 21P1 fluorescence after RF discharge is turned off . The absolute frequency metrology of the ECDL is carried out by an Er-fiber optical frequency comb (OFC). The two-photon spectrum is obtained by tuning the repetition frequency of the OFC. The 21S0-31D2 frequency is determined to be 594414291.967 (80) MHz in He-4. More results will be presented at the annual meeting.

CW 3μm lasing via two-photon pumping in cesium vapor with a 1W source

Science.gov (United States)

Haluska, Nathan D.; Rice, Christopher A.; Perram, Glen P.

2018-02-01

We report the first CW lasing from two-photon pumping via a virtual state. Pulsed and the CW lasing of the 3096 nm 72 P1/2 to 72 S1/2 line are observed from degenerate two-photon pumping of the cesium 72 S1/2 to 62 D3/2 transition. High intensity pulses excite over 17 lasing wavelengths. Under lower intensity CW excitation, 3 μm lasing is still observed with efficiencies of 0.7%. CW experiments utilized a Cs heat pipe at 150 °C to 270 °C, and a highly-focused, single pass, Ti-Sapphire pump with no aid of a cavity. Unlike normal DPALS, this architecture does not require buffer gas, and heat is released optically so a flowing system is not required. Both suggest a very simple device with excellent beam quality is possible. This proof of concept can be greatly enhanced with more optimal conditions such as non-degenerate pumping to further increase the two-photon pump cross section and the addition of a cavity to improve mode volume overlap. These improvements may lead to an increase in efficiencies to a theoretical maximum of 14%. Results suggest two-photon pumping with diodes is feasible.

Investigation of the two-photon polymerisation of a Zr-based inorganic-organic hybrid material system

International Nuclear Information System (INIS)

Bhuian, B.; Winfield, R.J.; O'Brien, S.; Crean, G.M.

2006-01-01

Two-photon polymerisation of photo-sensitive materials allows the fabrication of three dimensional micro- and nano-structures for photonic, electronic and micro-system applications. However the usable process window and the applicability of this fabrication technique is significantly determined by the properties of the photo-sensitive material employed. In this study investigation of a custom inorganic-organic hybrid system, cross-linked by a two-photon induced process, is described. The material was produced by sol-gel synthesis using a silicon alkoxide species that also possessed methacrylate functionality. Stabilized zirconium alkoxide precursors were added to the precursor solution in order to reduce drying times and impart enhanced mechanical stability to deposited films. This enabled dry films to be used in the polymerisation process. A structural, optical and mechanical analysis of the optimised sol-gel material is presented. A Ti:sapphire laser with 80 MHz repetition rate, 100 fs pulse duration and 795 nm is used. The influence of both material system and laser processing parameters including: laser power, photo-initiator concentration and zirconium loading, on achievable micro-structure and size is presented

The ATLAS Run-2 Trigger: Design, Menu, Performance and Operational Aspects

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00219584; The ATLAS collaboration

2016-01-01

The LHC, at design capacity, has a bunch-crossing rate of 40 MHz whereas the ATLAS experiment has an average recording rate of about 1000 Hz. To reduce the rate of events but still maintain high efficiency of selecting rare events such as physics signals beyond the Standard Model, a two-level trigger system is used in ATLAS. Events are selected based on physics signatures such as presence of energetic leptons, photons, jets or large missing energy. Despite the limited time available for processing collision events, the trigger system is able to exploit topological informations, as well as using multi-variate methods. In total, the ATLAS trigger systems consists of thousands of different individual triggers. The ATLAS trigger menu specifies which triggers are used during data taking and how much rate a given trigger is allocated. This menu reflects not only the physics goals of the collaboration but also takes into consideration the instantaneous luminosity of the LHC and the design limits of the ATLAS detecto...

Tunable two-photon correlation in a double-cavity optomechanical system

Directory of Open Access Journals (Sweden)

Zhi-Bo Feng

2015-12-01

Full Text Available Correlated photons are essential sources for quantum information processing. We propose a practical scheme to generate pairs of correlated photons in a controllable fashion from a double-cavity optomechanical system, where the variable optomechanical coupling strength makes it possible to tune the photon correlation at our will. The key operation is based on the repulsive or attractive interaction between the two photons intermediated by the mechanical resonator. The present protocol could provide a potential approach to coherent control of the photon correlation using the optomechanical cavity.

Studies and comparisons of two photon-tagging systems for the production of monochromatic photon beams for photonuclear experiments

International Nuclear Information System (INIS)

Aniel, Thierry.

1982-06-01

The performance of photon beams obtained by two different tagging processes (tagging of ''hard'' annihilation photons with ''soft'' associated photons, tagging of bremstrahlung photons with associated electrons) on the same facility was studied. The two processes are described and experimental results on the characteristics of the resulting beams given. The respective advantages of both methods are compared with one another and with those of a quasi-monochromatic beam obtained by the in-flight annihilation of a positron beam. A development based on the second process is then studied together with its applications to photonuclear physics [fr

Modeling and Optimization of Optical Half Adder in Two Dimensional Photonic Crystals

Science.gov (United States)

Sonth, Mahesh V.; Soma, Savita; Gowre, Sanjaykumar C.; Biradar, Nagashettappa

2018-05-01

The output of photonic integrated devices is enhanced using crystal waveguides and cavities but optimization of these devices is a topic of research. In this paper, optimization of the optical half adder in two-dimensional (2-D) linear photonic crystals using four symmetric T-shaped waveguides with 180° phase shift inputs is proposed. The input section of a T-waveguide acts as a beam splitter, and the output section acts as a power combiner. The constructive and destructive interference phenomenon will provide an output optical power. Output port Cout will receive in-phase power through the 180° phase shifter cavity designed near the junction. The optical half adder is modeled in a 2-D photonic crystal using the finite difference time domain method (FDTD). It consists of a cubic lattice with an array of 39 × 43 silicon rods of radius r 0.12 μm and 0.6 μm lattice constant a. The extinction ratio r e of 11.67 dB and 12.51 dB are achieved at output ports using the RSoft FullWAVE-6.1 software package.

A photon position sensor consisting of single-electron circuits

International Nuclear Information System (INIS)

Kikombo, Andrew Kilinga; Amemiya, Yoshihito; Tabe, Michiharu

2009-01-01

This paper proposes a solid-state sensor that can detect the position of incident photons with a high spatial resolution. The sensor consists of a two-dimensional array of single-electron oscillators, each coupled to its neighbors through coupling capacitors. An incident photon triggers an excitatory circular wave of electron tunneling in the oscillator array. The wave propagates in all directions to reach the periphery of the array. By measuring the arrival time of the wave at the periphery, we can know the position of the incident photon. The tunneling wave's generation, propagation, arrival at the array periphery, and the determination of incident photon positions are demonstrated with the results of Monte Carlo based computer simulations.

Enhanced linear photonic nanojet generated by core-shell optical microfibers

Science.gov (United States)

Liu, Cheng-Yang; Yen, Tzu-Ping; Chen, Chien-Wen

2017-05-01

The generation of linear photonic nanojet using core-shell optical microfiber is demonstrated numerically and experimentally in the visible light region. The power flow patterns for the core-shell optical microfiber are calculated by using the finite-difference time-domain method. The focusing properties of linear photonic nanojet are evaluated in terms of length and width along propagation and transversal directions. In experiment, the silica optical fiber is etched chemically down to 6 μm diameter and coated with metallic thin film by using glancing angle deposition. We show that the linear photonic nanojet is enhanced clearly by metallic shell due to surface plasmon polaritons. The large-area superresolution imaging can be performed by using a core-shell optical microfiber in the far-field system. The potential applications of this core-shell optical microfiber include micro-fluidics and nano-structure measurements.

Resisting distraction and response inhibition trigger similar enhancements of future performance.

Science.gov (United States)

Bissett, Patrick G; Grant, Lauren D; Weissman, Daniel H

2017-10-01

Resisting distraction and response inhibition are crucial aspects of cognitive control. Interestingly, each of these abilities transiently improves just after it is utilized. Competing views differ, however, as to whether utilizing either of these abilities (e.g., resisting distraction) enhances future performance involving the other ability (e.g., response inhibition). To distinguish between these views, we combined a Stroop-like task that requires resisting distraction with a restraint variant of the stop-signal task that requires response inhibition. We observed similar sequential-trial effects (i.e., performance enhancements) following trials in which participants (a) resisted distraction (i.e., incongruent go trials) and (b) inhibited a response (i.e., congruent stop trials). First, the congruency effect in go trials, which indexes overall distractibility, was smaller after both incongruent go trials and congruent stop trials than it was after congruent go trials. Second, stop failures were less frequent after both incongruent go trials and congruent stop trials than after congruent go trials. A control experiment ruled out the possibility that perceptual conflict or surprise engendered by occasional stop signals triggers sequential-trial effects independent of stopping. Thus, our findings support a novel, integrated view in which resisting distraction and response inhibition trigger similar sequential enhancements of future performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Resonance fluorescence spectrum in a two-band photonic bandgap crystal

Science.gov (United States)

Lee, Ray-Kuang; Lai, Yinchieh

2003-05-01

Steady state resonance fluorescence spectra from a two-level atom embedded in a photonic bandgap crystal and resonantly driven by a classical pump light are calculated. The photonic crystal is considered to be with a small bandgap which is in the order of magnitude of the Rabi frequency and is modeled by the anisotropic two-band dispersion relation. Non-Markovian noises caused by the non-uniform distribution of photon density states near the photonic bandgap are taken into account by a new approach which linearizes the optical Bloch equations by using the Liouville operator expansion. Fluorescence spectra that only exhibit sidebands of the Mollow triplet are found, indicating that there is no coherent Rayleigh scattering process.

Slow-light enhancement of spontaneous emission in active photonic crystal waveguides

DEFF Research Database (Denmark)

Ek, Sara; Chen, Yaohui; Semenova, Elizaveta

2012-01-01

Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising...... results for future compact devices for terabit/s communication, such as miniaturised semiconductor optical amplifiers and mode-locked lasers....

Resonantly-enhanced, four-photon ionization of krypton at laser intensities exceeding 1013 W/cm2

International Nuclear Information System (INIS)

Perry, M.D.; Landen, O.L.; Campbell, E.M.

1987-12-01

The yield of singly- and multiply- charged ions of krypton and xenon is presented as a function of laser intensity and frequency. The measurements were performed using the second harmonic output of a well-characterized, tunable picosecond dye laser in the range 285 to 310 nm at laser intensities from 1 x 10 12 to 10 14 W/cm 2 . Enhancement of the Kr + yield by two orders of magnitude by three-photon resonant, four-photon ionization is observed in the vicinity of the 4d'[5/2] 3 and the 4d[3/2] 1 intermediate states. A model incorporating line shifts and widths scaling linearly with intensity is in good agreement with the experimental results

Effect of morphology and solvent on two-photon absorption of nano zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Kavitha, M.K. [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); Haripadmam, P.C.; Gopinath, Pramod; Krishnan, Bindu [Department of Physics, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); John, Honey, E-mail: honey@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India)

2013-05-15

Highlights: ► ZnO nanospheres and triangular structures synthesis by novel precipitation technique. ► The effect of precursor concentration on the size and shape of nano ZnO. ► Open aperture Z-scan measurements of the ZnO nanoparticle dispersions. ► Nanospheres exhibit higher two photon absorption coefficient than triangular nanostructures. ► Nanospheres dispersed in water exhibit higher two photon absorption coefficient than its dispersion in 2-propanol. - Abstract: In this paper, we report the effect of morphology and solvent on the two-photon absorption of nano zinc oxide. Zinc oxide nanoparticles in two different morphologies like nanospheres and triangular nanostructures are synthesized by novel precipitation technique and their two-photon absorption coefficient is measured using open aperture Z-scan technique. Experimental results show that the zinc oxide nanospheres exhibit higher two-photon absorption coefficient than the zinc oxide triangular nanostructures. The zinc oxide nanospheres dispersed in water exhibit higher two-photon absorption coefficient than that of its dispersion in 2-propanol. The zinc oxide nanospheres dispersed in water shows a decrease in two-photon absorption coefficient with an increase in on-axis irradiance. The result confirms the dependence of shape and solvent on the two-photon absorption of nano zinc oxide.

Quantum state detection and state preparation based on cavity-enhanced nonlinear interaction of atoms with single photon

Science.gov (United States)

Hosseini, Mahdi

Our ability to engineer quantum states of light and matter has significantly advanced over the past two decades, resulting in the production of both Gaussian and non-Gaussian optical states. The resulting tailored quantum states enable quantum technologies such as quantum optical communication, quantum sensing as well as quantum photonic computation. The strong nonlinear light-atom interaction is the key to deterministic quantum state preparation and quantum photonic processing. One route to enhancing the usually weak nonlinear light-atom interactions is to approach the regime of cavity quantum electrodynamics (cQED) interaction by means of high finesse optical resonators. I present results from the MIT experiment of large conditional cross-phase modulation between a signal photon, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. I also present a scheme to probabilistically change the amplitude and phase of a signal photon qubit to, in principle, arbitrary values by postselection on a control photon that has interacted with that state. Notably, small changes of the control photon polarization measurement basis by few degrees can substantially change the amplitude and phase of the signal state. Finally, I present our ongoing effort at Purdue to realize similar peculiar quantum phenomena at the single photon level on chip scale photonic systems.

Optimization of Tapered Photonic Crystal Fibers for Blue-Enhanced Supercontinuum Generation

DEFF Research Database (Denmark)

Møller, Uffe; Sørensen, Simon Toft; Larsen, Casper

2012-01-01

Tapering of photonic crystal fibers is an effective way of shifting the dispersive wavelength edge of a supercontinuum spectrum down in the deep-blue. We discuss the optimum taper profile for blue-enhanced supercontinuum generation....

Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus

Energy Technology Data Exchange (ETDEWEB)

Song, Minsoo; Yoon, Tai Hyun [Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea, Republic of)

2013-02-15

We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s{sup 2} {sup 1}S{sub 0}{r_reversible} 6s7s {sup 1}S{sub 0}) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm{sup 3} and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s{sup 1}S{sub 0} state via the intercombination 6s6p{sup 3}P{sub 1} state with a high signal-to-noise ratio even at the temperature of 340 Degree-Sign C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle.

Photon strength and the low-energy enhancement

Energy Technology Data Exchange (ETDEWEB)

Wiedeking, M. [iThemba LABS, P.O. Box 722, Somerset West 7129 (South Africa); Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Hatarik, R.; Lesher, S. R.; Scielzo, N. D. [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Krtička, M. [Faculty of Mathematics and Physics, Charles University, V Holešovickách 2, Prague 8 (Czech Republic); Allmond, J. M. [Department of Physics, University of Richmond, Virginia 23173 (United States); Basunia, M. S.; Fallon, P.; Firestone, R. B.; Lake, P. T.; Lee, I-Y.; Paschalis, S.; Petri, M.; Phair, L. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Goldblum, B. L. [Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States)

2014-08-14

Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in {sup 95}Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to {sup 95}Mo photon strength function data measured at the University of Oslo.

Aspects of two-photon physics at linear e+e- colliders

International Nuclear Information System (INIS)

Drees, M.; Godbole, R.M.

1993-01-01

We discuss various reactions at future e + e - and γγ colliders involving real (beamstrahlung or backscattered laser) or quasi-real (bremsstrahlung) photons in the initial state and hadrons in the final state. The production of two central jets with large transverse momentum p T is described in some detail; we give distributions for the rapidity and p T of the jets as well as the di-jet invariant mass, and discuss the relative importance of various initial state configurations and the uncertainties that arise from the at present rather poor knowledge of the parton content of the photon. We also present results for 'mono-jet' production where one jet goes down a beam pipe, for the production of charm, bottom and top quarks, and for single production of W and Z bosons. Where appropriate, the two-photon processes are compared with annihilation reactions leading to similar final states. We also argue that the behaviour of the total inelastic γγ cross section at high energies will probably have little impact on the severity of background problems caused by soft and semi-hard ('minijet') two-photon reactions. We find very large differences in cross sections for all two-photon processes between existing designs for future e + e - colliders, due to the different beamstrahlung spectra; in particular, both designs with >1 events per bunch crossing exist. The number of hardronic two-photon events is expected to rise quickly with the beam energy. Hadronic backgrounds will be even worse if the e + e - collider is converted into a γγ collider. (orig.)

Two-Photon Fluorescence Microscopy Developed for Microgravity Fluid Physics

Science.gov (United States)

Fischer, David G.; Zimmerli, Gregory A.; Asipauskas, Marius

2004-01-01

Recent research efforts within the Microgravity Fluid Physics Branch of the NASA Glenn Research Center have necessitated the development of a microscope capable of high-resolution, three-dimensional imaging of intracellular structure and tissue morphology. Standard optical microscopy works well for thin samples, but it does not allow the imaging of thick samples because of severe degradation caused by out-of-focus object structure. Confocal microscopy, which is a laser-based scanning microscopy, provides improved three-dimensional imaging and true optical sectioning by excluding the out-of-focus light. However, in confocal microscopy, out-of-focus object structure is still illuminated by the incoming beam, which can lead to substantial photo-bleaching. In addition, confocal microscopy is plagued by limited penetration depth, signal loss due to the presence of a confocal pinhole, and the possibility of live-cell damage. Two-photon microscopy is a novel form of laser-based scanning microscopy that allows three-dimensional imaging without many of the problems inherent in confocal microscopy. Unlike one-photon microscopy, it utilizes the nonlinear absorption of two near-infrared photons. However, the efficiency of two-photon absorption is much lower than that of one-photon absorption because of the nonlinear (i.e., quadratic) electric field dependence, so an ultrafast pulsed laser source must typically be employed. On the other hand, this stringent energy density requirement effectively localizes fluorophore excitation to the focal volume. Consequently, two-photon microscopy provides optical sectioning and confocal performance without the need for a signal-limiting pinhole. In addition, there is a reduction in photo-damage because of the longer excitation wavelength, a reduction in background fluorescence, and a 4 increase in penetration depth over confocal methods because of the reduction in Rayleigh scattering.

Towards a measurement of the two-photon decay width of the Higgs boson at a photon collider

International Nuclear Information System (INIS)

Moenig, K.; Rosca, A.

2007-05-01

A study of the measurement of the two photon decay width times the branching ratio of a Higgs boson with the mass of 120 GeV in photon-photon collisions is presented, assuming a γγ integrated luminosity of 80 fb -1 in the high energy part of the spectrum. The analysis is based on the reconstruction of the Higgs events produced in the γγ→H process, followed by the decay f the Higgs into a b anti b pair. A statistical error of the measurement of the two-photon width, Γ(H→γγ), times the branching ratio of the Higgs boson, BR(H →b anti b) is found to be 2.1 % for one year of data taking. (orig.)

Sub-threshold investigation of two coupled photonic crystal cavities

DEFF Research Database (Denmark)

Schubert, Martin; Frandsen, Lars Hagedorn; Skovgård, Troels Suhr

2009-01-01

The behavior of two coupled photonic crystal membrane cavities with quantum dots separated by different number of holes is investigated. The measured spectral splitting with increased coupling is verified by 3D calculations and discussed.......The behavior of two coupled photonic crystal membrane cavities with quantum dots separated by different number of holes is investigated. The measured spectral splitting with increased coupling is verified by 3D calculations and discussed....

Modelling and design of complete photonic band gaps in two ...

Indian Academy of Sciences (India)

In this paper, we investigate the existence and variation of complete photonic band gap size with the introduction of asymmetry in the constituent dielectric rods with honeycomb lattices in two-dimensional photonic crystals (PhC) using the plane-wave expansion (PWE) method. Two examples, one consisting of elliptical rods ...

Plasmonic enhancement in BiVO4 photonic crystals for efficient water splitting.

Science.gov (United States)

Zhang, Liwu; Lin, Chia-Yu; Valev, Ventsislav K; Reisner, Erwin; Steiner, Ullrich; Baumberg, Jeremy J

2014-10-15

Photo-electrochemical water splitting is a very promising and environmentally friendly route for the conversion of solar energy into hydrogen. However, the solar-to-H2 conversion efficiency is still very low due to rapid bulk recombination of charge carriers. Here, a photonic nano-architecture is developed to improve charge carrier generation and separation by manipulating and confining light absorption in a visible-light-active photoanode constructed from BiVO4 photonic crystal and plasmonic nanostructures. Synergistic effects of photonic crystal stop bands and plasmonic absorption are observed to operate in this photonic nanostructure. Within the scaffold of an inverse opal photonic crystal, the surface plasmon resonance is significantly enhanced by the photonic Bragg resonance. Nanophotonic photoanodes show AM 1.5 photocurrent densities of 3.1 ± 0.1 mA cm(-2) at 1.23 V versus RHE, which is among the highest for oxide-based photoanodes and over 4 times higher than the unstructured planar photoanode. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A new approach to dual-color two-photon microscopy with fluorescent proteins

Directory of Open Access Journals (Sweden)

Rebane Aleks

2010-02-01

Full Text Available Abstract Background Two-photon dual-color imaging of tissues and cells labeled with fluorescent proteins (FPs is challenging because most two-photon microscopes only provide one laser excitation wavelength at a time. At present, methods for two-photon dual-color imaging are limited due to the requirement of large differences in Stokes shifts between the FPs used and their low two-photon absorption (2PA efficiency. Results Here we present a new method of dual-color two-photon microscopy that uses the simultaneous excitation of the lowest-energy electronic transition of a blue fluorescent protein and a higher-energy electronic transition of a red fluorescent protein. Conclusion Our method does not require large differences in Stokes shifts and can be extended to a variety of FP pairs with larger 2PA efficiency and more optimal imaging properties.

Theory of the effect of third-harmonic generation on three-photon resonantly enhanced multiphoton ionization in focused beams

International Nuclear Information System (INIS)

Payne, M.G.; Garrett, W.R.

1983-01-01

Multiphoton ionization in the region near a three-photon resonance is treated for focused, plane-polarized Gaussian beams with diffraction-limited beam divergence. In this situation, a third-harmonic field is generated within the laser beam. At, and very near, three-photon resonance the driving rate for the upper-state probability amplitude due to one-photon absorption of third-harmonic light becomes nearly equal to the corresponding three-photon rate due to the laser field, but these effects are 180 0 out of phase. As a consequence of this cancellation between two pumping terms, the three-photon resonance line essentially disappears at moderate concentrations and the observed ionization has a line shape that is close to the phase-matching curve for third-harmonic generation. The ionization signal, near but not on the resonance, is due almost entirely to absorption of third-harmonic photons plus other laser photons; three-photon resonantly enhanced multiphoton ionization by the laser is much weaker. This is particularly true on the blue side of the three-photon resonance at detunings where phase matching occurs. The problem is treated quite generally with predictions of the full line shape for n-photon ionization and third-harmonic light generation near three-photon resonance, including the rather strong influences of positively dispersive buffer gases. We also show that the cancellation between the one-photon and the three-photon process is partially spoiled in the presence of a counterpropagating beam at the same frequency

The CMS electron and photon trigger for the LHC Run 2

CERN Document Server

Beschi, Andrea

2017-01-01

to optimally reconstruct the electromagnetic trigger objects. The performance of the new trigger system will be presented, based on proton-proton collision data collected in Run II. The selection techniques used to trigger efficiently will be presented, along with the strategies employed to guarantee efficient triggering for new resonances and other new physics signals invo...

Nonresonant absorption of one photon by one atom and resonant absorption of two photons by two atoms

International Nuclear Information System (INIS)

Mizushima, Masataka

1990-01-01

When a radiation field of frequency ω 1 interacts with atoms, etch of which has a transition frequency ω ba =(E b -E a )/h, with ω 1 -ω ba =Δ≠0, nonresonant absorption can take place with probability P 1 inversely proportional to Δ 2 (a pressure broadening). When another radiation field of frequency ω 2 , such that ω 1 +ω 2 =2ω ba, interacts simultaneously with the gas a resonant two-photon absorption can take place in addition to the nonresonant absorption. The probability of this two-photon absorption process, P 2 , is found to be inversely proportional to Δ 4 . If Ω=| | is the Rabi frequency of the transition, it is found that P 2 /(P 1 (Δ)+P 1 (-Δ)) is given by 12 {Ω(-Δ)Ω(-Δ)} 2 / {Δ 2 (Ω(-Δ) 2 + Ω(Δ) 2 )}. (author)

Two-photon emission and multiphoton absorption by atoms

International Nuclear Information System (INIS)

Mu, X.

1988-01-01

This thesis consists of investigations of two problems concerning photon-atom interactions. The first topic deals with two-photon transitions in atomic inner shells. An independent-particle model has been used to describe the two-photon transitions between different inner-shell electron states. The first relativistic self-consistent-field calculation of these transition rates in Ag, Mo, and Xe has been carried out. The theoretical results are compared with recent measurements. Good agreement with measured rates is found except in some cases where more reliable experiments still need to be done. The second topic is multiphoton multiionization of atoms. The maximum entropy principle has been employed in this theoretical investigation. A detailed statistical analysis of measured ionic charge distributions produced in strong laser pulses has been carried out. The results of this analysis indicates that the charge-state distribution is a Poissonian, rather than the binomial which prevails under infrared radiation, and hence that ionization occurs stepwise during the pulse. This result is shown to be consistent with experimental data

Electron-positron pair production by two identical photons in the nuclear field

International Nuclear Information System (INIS)

Smirnov, A.I.

1977-01-01

In the Born approximation of the perturbation theory considered is a nonlinear effect of the electron-positron pair production by two identical photons in the Coulomb field of an atomic nucleus. The kinematic version of identical photons is studied. All the particles are considered to be nonpolarized. The calculation of the differential probability of the effect has been carried out earlier by the Feynman method. The total probability of the effect in limiting energy ranges is determined by integrating the formulas of the pair component distribution over energies. The probabilities of the electron-positron pair production and fusion of two photons into one in the nucleus field have been compared for the case of identical quanta. From the comparison of the results of analyzing both the nonlinear effects it follows that in the high-energy range the electron-positron pair production by two identical photons in the nucleus field extremely predominates over the fusion of two photons into one photon in the same field

Confronting the MSSM and the NMSSM with the discovery of a signal in the two photon channel at the LHC

Energy Technology Data Exchange (ETDEWEB)

Benbrik, R.; Heinemeyer, S. [Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain); Gomez Bock, M. [Universidad Autonoma de Puebla (Mexico). Facultad de Ciencias Fisico-Matematicas; Staal, O.; Weiglein, G.; Zeune, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-07-15

We confront the discovery of a boson decaying to two photons, as reported recently by ATLAS and CMS, with the corresponding predictions in the Minimal Supersymmetric Standard Model (MSSM) and the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We perform a scan over the relevant regions of parameter space in both models and evaluate the MSSM and NMSSM predictions for the dominant Higgs production channel and the photon photon decay channel. Taking into account the experimental constraints from previous direct searches, flavour physics, electroweak measurements as well as theoretical considerations, we find that a Higgs signal in the two photon channel with a rate equal to, or above, the SM prediction is viable over the full mass range 123 GeVenhancement of the {gamma}{gamma} rate, compatible with the signal strengths observed by ATLAS and CMS, is possible in both the MSSM and the NMSSM, and we analyse in detail different mechanisms in the two models that can give rise to such an enhancement. We briefly discuss also our predictions in the two models for the production and subsequent decay into two photons of a CP-odd Higgs boson.

Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits.

Science.gov (United States)

Yu, Leo; Natarajan, Chandra M; Horikiri, Tomoyuki; Langrock, Carsten; Pelc, Jason S; Tanner, Michael G; Abe, Eisuke; Maier, Sebastian; Schneider, Christian; Höfling, Sven; Kamp, Martin; Hadfield, Robert H; Fejer, Martin M; Yamamoto, Yoshihisa

2015-11-24

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.

Enhancement of molecular sensitivity in positron emission tomography with quantum correlation of γ-ray photons

Science.gov (United States)

Sato, K.; Kobayashi, Y.

2015-05-01

Enhancement of molecular sensitivity in positron emission tomography (PET) has long been discussed with respect to imaging instrumentation and algorithms for data treatment. Here, the molecular sensitivity in PET is discussed on the basis of 2-dimensional coincident measurements of 511 keV γ ray photons resultant from two-photon annihilation. Introduction of an additional selection window based on the energy sum and difference of the coincidently measured γ ray photons, without any significant instrumental and algorithmic changes, showed an improvement in the signal-to-noise ratio (SNR) by an order of magnitude. Improvement of performance characteristics in the PET imaging system was demonstrated by an increase in the noise equivalent count rate (NECR) which takes both the SNR and the detection efficiency into consideration. A further improvement of both the SNR and the NECR is expected for the present system in real clinical and in-vivo environments, where much stronger positron sources are employed.

Enhancement of molecular sensitivity in positron emission tomography with quantum correlation of γ-ray photons

International Nuclear Information System (INIS)

Sato, K.; Kobayashi, Y.

2015-01-01

Enhancement of molecular sensitivity in positron emission tomography (PET) has long been discussed with respect to imaging instrumentation and algorithms for data treatment. Here, the molecular sensitivity in PET is discussed on the basis of 2-dimensional coincident measurements of 511 keV γ ray photons resultant from two-photon annihilation. Introduction of an additional selection window based on the energy sum and difference of the coincidently measured γ ray photons, without any significant instrumental and algorithmic changes, showed an improvement in the signal-to-noise ratio (SNR) by an order of magnitude. Improvement of performance characteristics in the PET imaging system was demonstrated by an increase in the noise equivalent count rate (NECR) which takes both the SNR and the detection efficiency into consideration. A further improvement of both the SNR and the NECR is expected for the present system in real clinical and in-vivo environments, where much stronger positron sources are employed

Enhancing the photon-extraction efficiency of site-controlled quantum dots by deterministically fabricated microlenses

Science.gov (United States)

Kaganskiy, Arsenty; Fischbach, Sarah; Strittmatter, André; Rodt, Sven; Heindel, Tobias; Reitzenstein, Stephan

2018-04-01

We report on the realization of scalable single-photon sources (SPSs) based on single site-controlled quantum dots (SCQDs) and deterministically fabricated microlenses. The fabrication process comprises the buried-stressor growth technique complemented with low-temperature in-situ electron-beam lithography for the integration of SCQDs into microlens structures with high yield and high alignment accuracy. The microlens-approach leads to a broadband enhancement of the photon-extraction efficiency of up to (21 ± 2)% and a high suppression of multi-photon events with g (2)(τ = 0) SPSs which, can be applied in photonic quantum circuits and advanced quantum computation schemes.

Two-photon activation of endogenous store-operated calcium channels without optogenetics

Science.gov (United States)

Cheng, Pan; Tang, Wanyi; He, Hao

2018-02-01

Store-operated calcium (SOC) channels, regulated by intracellular Ca2+ store, are the essential pathway of calcium signaling and participate in a wide variety of cellular activities such as gene expression, secretion and immune response1. However, our understanding and regulation of SOC channels are mainly based on pharmacological methods. Considering the unique advantages of optical control, optogenetic control of SOC channels has been developed2. However, the process of genetic engineering to express exogenous light-sensitive protein is complicated, which arouses concerns about ethic difficulties in some research of animal and applications in human. In this report, we demonstrate rapid, robust and reproducible two-photon activation of endogenous SOC channels by femtosecond laser without optogenetics. We present that the short-duration two-photon scanning on subcellular microregion induces slow Ca2+ influx from extracellular medium, which can be eliminated by removing extracellular Ca2+. Block of SOC channels using various pharmacological inhibitors or knockdown of SOC channels by RNA interference reduce the probability of two-photon activated Ca2+ influx. On the contrary, overexpression of SOC channels can increase the probability of Ca2+ influx by two-photon scanning. These results collectively indicate Ca2+ influx through two-photon activated SOC channels. Different from classical pathway of SOC entry activated by Ca2+ store depletion, STIM1, the sensor protein of Ca2+ level in endoplasmic reticulum, does not show any aggregation or migration in this two-photon activated Ca2+ influx, which rules out the possibility of intracellular Ca2+ store depletion. Thereby, we propose this all-optical method of two-photon activation of SOC channels is of great potential to be widely applied in the research of cell calcium signaling and related biological research.

Ultra-fast flash observatory for detecting the early photons from gamma-ray bursts

DEFF Research Database (Denmark)

Lim, H.; Jeong, S.; Ahn, K.-B.

) for the fast measurement of the UV-optical photons from GRBs, and a gamma-ray monitor for energy measurement. The triggering is done by the UFFO burst Alert & Trigger telescope (UBAT) using the hard X-ray from GRBs and the UV/optical Trigger Assistant Telescope (UTAT) using the UV/optical photons from GRBs...

Theory of the effect of odd-photon destructive interference on optical shifts in resonantly enhanced multiphoton excitation and ionization

International Nuclear Information System (INIS)

Payne, M.G.; Deng, L.; Garrett, W.R.

1998-01-01

We present a theory for two- and three-photon excitation, optical shifting, and four-wave mixing when a first laser is tuned onto, or near, a two-photon resonance and a second much more intense laser is tuned near or on resonance between the two-photon resonance and a second excited state. When the second excited state has a dipole-allowed transition back to the ground state and the concentration is sufficiently high, a destructive interference is produced between three-photon coupling of the ground state and the second excited state and one-photon coupling between the same states by the internally generated four-wave mixing field. This interference leads to several striking effects. For instance, as the onset of the interference occurs, the optical shifts in the two-photon resonance excitation line shape become smaller in copropagating geometry so that the line shapes for multiphoton ionization enhanced by the two-photon resonance eventually become unaffected by the second laser. In the same range of concentrations the four-wave mixing field evolves to a concentration-independent intensity. With counterpropagating laser beams the line shape exhibits normal optical shifts like those observed for both copropagating and counterpropagating laser beams at very low concentrations. The theoretical work presented here extends our earlier works by including the effect of laser bandwidth and by removing the restriction of having the second laser be tuned far from three-photon resonance. In this way we have now included, as a special case, the effect of both laser bandwidth and interference on laser-induced transparency. Unlike other effects related to odd-photon destructive interference, the effect of a broad bandwidth is to bring about the predicted effects at much lower concentrations. Studies in rubidium show good agreement between theory and experiment for both ionization line shapes and four-wave mixing intensity as a function of concentration. copyright 1998 The

Saturated two-photon absorption by atoms in a perturber gas

International Nuclear Information System (INIS)

Nienhuis, G.

1980-01-01

We derive a general expression for the two-photon absorption spectrum of a three-state atom excited by two mono-chromatic radiation fields. Collisional line-broadening effects are incorporated, and the result allows inclusion of profiles with a validity outside the impact limit. Results of previous work are recovered in the appropriate limits. Saturation affects the different lines in the two-photon absorption spectrum in a different fashion. (orig.)

Selection rules for the dematerialization of a particle into two photons

International Nuclear Information System (INIS)

Yang, C.N.

1983-01-01

Selection rules governing the disintegration of a particle into two photons are derived from the general principle of invariance under rotation and inversion. The polarization state of the photons is completely fixed by the selection rules for initial particles with spin less than 2. These results which are independent of any specific assumption about the interactions may possibly offer a method of deciding the symmetry nature of mesons which decay into two photons. 4 tables

Detailed analysis of events from high-energy X-ray photons impinging on a two-phase front-illuminated CCD

International Nuclear Information System (INIS)

Levato, T.; Labate, L.; Galimberti, M.; Giulietti, A.; Giulietti, D.; Gizzi, L.A.

2008-01-01

A study of the single-photon events generated by the interaction of X-rays up to 60 keV with a true two-phase charge coupled device (CCD) is reported. In particular, a relevant classification of the events is carried out according to their size and collected charge. This classification shows the occurrence of two main groups, characterized by a quite large difference in the ADU values that has been observed between events having different sizes but coming from photons with the same energy. Based upon 2D numerical calculations accounting for the charge cloud dynamics, diffusion and recombination, an explanation is suggested for this difference, arising from the difference in the electric field strength in the point of initial interaction. Moreover, the relative abundance of these two groups was found to be energy dependent. A model accounting for the true two-phase pixel structure was found to be a valid tool for a correct prediction of this abundance and an enhanced reconstruction of the spectra of the impinging photons

Two-photon collisions and short-distance tests of quantum chromodynamics

International Nuclear Information System (INIS)

Brodsky, S.J.

1978-12-01

The physics of two-photon collisions in e +- storage rings is reviewed with emphasis on the predictions of perturbative quantum chromodynamics for high transverse momentum reactions. It is noted that because of the remarkable scaling properties predicted by the theory, two-photon collisions may be proved one of the cleanest tests of the quantum chromodynamics picture of short distance hadron dynamics. In order to contrast these predictions for photon-induced reactions with those for incident hadrons, predictions from quantum chromodynamics for hadron structure functions and form factors at large momentum transfer are also discussed. 55 references

Source of single photons and interferometry with one photon. From the Young's slit experiment to the delayed choice; Source de photons uniques et interferences a un seul photon. De l'experience des fentes d'Young au choix retarde

Energy Technology Data Exchange (ETDEWEB)

Jacques, V

2007-11-15

This manuscript is divided in two independent parts. In the first part, we study the wave-particle duality for a single photon emitted by the triggered photoluminescence of a single NV color center in a diamond nano-crystal. We first present the realization of a single-photon interference experiment using a Fresnel's bi-prism, in a scheme equivalent to the standard Young's double-slit textbook experiment. We then discuss the complementarity between interference and which-path information in this two-path interferometer. We finally describe the experimental realization of Wheeler's delayed-choice Gedanken experiment, which is a fascinating and subtle illustration of wave-particle duality. The second part of the manuscript is devoted to the efficiency improvement of single-photon sources. We first describe the implementation of a new single-photon source based on the photoluminescence of a single nickel-related defect center in diamond. The photophysical properties of such defect make this single-photon source well adapted to open-air quantum cryptography. We finally demonstrate an original method that leads to an improvement of single-molecule photo stability at room temperature. (author)

A mitochondrial targeted two-photon iridium(III) phosphorescent probe for selective detection of hypochlorite in live cells and in vivo.

Science.gov (United States)

Li, Guanying; Lin, Qian; Sun, Lingli; Feng, Changsheng; Zhang, Pingyu; Yu, Bole; Chen, Yu; Wen, Ya; Wang, Hui; Ji, Liangnian; Chao, Hui

2015-01-01

Endogenous hypochlorite ion (ClO(-)) is a highly reactive oxygen species (ROS) that is produced from hydrogen peroxide and chloride ions catalyzed by myeloperoxidase (MPO). And mitochondrion is one of the major sources of ROS including ClO(-). In the present work, a two-photon phosphorescent probe for ClO(-) in mitochondria was developed. An iridium(III) complex bearing a diaminomaleonitrile group as ClO(-) reactive moiety specifically responded to ClO(-) over other ions and ROSs. When the probe was reacted with ClO(-) to form an oxidized carboxylate product, a significant enhancement in phosphorescence intensity was observed under one-photon (402 nm) and two-photon (750 nm) excitation, with a two-photon absorption cross-section of 78.1 GM at 750 nm. More importantly, ICP-MS results and cellular images co-stained with Mito-tracker Green demonstrated that this probe possessed high specificity for mitochondria. This probe was applied in the one- and two-photon imaging of ClO(-) in vitro and in vivo. The results suggested endotoxin lipopolysaccharide (LPS) induced ClO(-) mostly generated in the liver of zebrafish. Copyright © 2015 Elsevier Ltd. All rights reserved.

Azimuthal correlations of high-p{sub T} photons and hadrons in Au+Au collisions at STAR

Energy Technology Data Exchange (ETDEWEB)

Dietel, T.

2006-07-01

The STAR experiment observed a modification of the azimuthal correlations between a trigger particle and associated particles in central Au+Au collisions, where trigger particles with 4 GeVtrigger}<6 GeV and associated particles with 2GeVtrigger}<4 GeV were selected. This thesis studies azimuthal correlations between regions of high energy deposition in the electro-magnetic calorimeter as trigger- and charged tracks as associated particles. The data sample had been enriched by online event selection, allowing for the selection of trigger particles with a transverse energy of more than 10 GeV and associated particles with more than 2, 3 or 4 GeV. The trigger particles are a mixture of photon pairs from the decays of neutral pions and single photons, mainly from photon-jet events, with small contributions from other hadron decays and fragmentation photons. (orig.)

Two-photon excitation of porphyrin-functionalized porous silicon nanoparticles for photodynamic therapy.

Science.gov (United States)

Secret, Emilie; Maynadier, Marie; Gallud, Audrey; Chaix, Arnaud; Bouffard, Elise; Gary-Bobo, Magali; Marcotte, Nathalie; Mongin, Olivier; El Cheikh, Khaled; Hugues, Vincent; Auffan, Mélanie; Frochot, Céline; Morère, Alain; Maillard, Philippe; Blanchard-Desce, Mireille; Sailor, Michael J; Garcia, Marcel; Durand, Jean-Olivier; Cunin, Frédérique

2014-12-03

Porous silicon nanoparticles (pSiNPs) act as a sensitizer for the 2-photon excitation of a pendant porphyrin using NIR laser light, for imaging and photodynamic therapy. Mannose-functionalized pSiNPs can be vectorized to MCF-7 human breast cancer cells through a mannose receptor-mediated endocytosis mechanism to provide a 3-fold enhancement of the 2-photon PDT effect. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-photon Microscopy and Polarimetry for Assessment of Myocardial Tissue Organization

Science.gov (United States)

Archambault-Wallenburg, Marika

Optical methods can provide useful tissue characterization tools. For this project, two-photon microscopy and polarized light examinations (polarimetry) were used to assess the organizational state of myocardium in healthy, infarcted, and stem-cell regenerated states. Two-photon microscopy visualizes collagen through second-harmonic generation and myocytes through two-photon excitation autofluorescence, providing information on the composition and structure/organization of the tissue. Polarimetry measurements yield a value of linear retardance that can serve as an indicator of tissue anisotropy, and with a dual-projection method, information about the anisotropy axis orientation can also be extracted. Two-photon microscopy results reveal that stem-cell treated tissue retains more myocytes and structure than infarcted myocardium, while polarimetry findings suggest that the injury caused by temporary ligation of a coronary artery is less severe and more diffuse that than caused by a permanent ligation. Both these methods show potential for tissue characterization.

Strong nonlinearity-induced correlations for counterpropagating photons scattering on a two-level emitter

DEFF Research Database (Denmark)

Nysteen, Anders; McCutcheon, Dara; Mørk, Jesper

2015-01-01

We analytically treat the scattering of two counterpropagating photons on a two-level emitter embedded in an optical waveguide. We find that the nonlinearity of the emitter can give rise to significant pulse-dependent directional correlations in the scattered photonic state, which could be quanti......We analytically treat the scattering of two counterpropagating photons on a two-level emitter embedded in an optical waveguide. We find that the nonlinearity of the emitter can give rise to significant pulse-dependent directional correlations in the scattered photonic state, which could...

Far-Field Focus and Dispersionless Anticrossing Bands in Two-Dimensional Photonic Crystals

Directory of Open Access Journals (Sweden)

Xiaoshuang Chen

2007-01-01

Full Text Available We review the simulation work for the far-field focus and dispersionless anticrossing bands in two-dimensional (2D photonic crystals. In a two-dimensional photonic-crystal-based concave lens, the far-field focus of a plane wave is given by the distance between the focusing point and the lens. Strong and good-quality far-field focusing of a transmitted wave, explicitly following the well-known wave-beam negative refraction law, can be achieved. The spatial frequency information of the Bloch mode in multiple Brillouin zones (BZs is investigated in order to indicate the wave propagation in two different regions. When considering the photonic transmission in a 2D photonic crystal composed of a negative phase-velocity medium (NPVM, it is shown that the dispersionless anticrossing bands are generated by the couplings among the localized surface polaritons of the NPVM rods. The photonic band structures of the NPVM photonic crystals are characterized by a topographical continuous dispersion relationship accompanied by many anticrossing bands.

Two-photon exclusive processes in quantum chromodynamics

Energy Technology Data Exchange (ETDEWEB)

Brodsky, S.J.

1986-07-01

QCD predictions for ..gamma gamma.. annihilation into single mesons, meson pairs, and baryon pairs are reviewed. Two-photon exclusive processes provide the most sensitive and practical measure of the distribution amplitudes, and thus a critical confrontation between QCD and experiment. Both the angular distribution and virtual photon mass dependence of these amplitudes are sensitive to the shapes of the phi (chi, Q). Novel effects involving the production of qq anti q anti q states at threshold are also discussed, and a new method is presented for systematically incorporating higher-order QCD corrections in ..gamma gamma.. reactions.

Two-photon exclusive processes in quantum chromodynamics

International Nuclear Information System (INIS)

Brodsky, S.J.

1986-07-01

QCD predictions for γγ annihilation into single mesons, meson pairs, and baryon pairs are reviewed. Two-photon exclusive processes provide the most sensitive and practical measure of the distribution amplitudes, and thus a critical confrontation between QCD and experiment. Both the angular distribution and virtual photon mass dependence of these amplitudes are sensitive to the shapes of the phi (chi, Q). Novel effects involving the production of qq anti q anti q states at threshold are also discussed, and a new method is presented for systematically incorporating higher-order QCD corrections in γγ reactions

Calorimetry triggering in ATLAS

CERN Document Server

Igonkina, O; Adragna, P; Aharrouche, M; Alexandre, G; Andrei, V; Anduaga, X; Aracena, I; Backlund, S; Baines, J; Barnett, B M; Bauss, B; Bee, C; Behera, P; Bell, P; Bendel, M; Benslama, K; Berry, T; Bogaerts, A; Bohm, C; Bold, T; Booth, J R A; Bosman, M; Boyd, J; Bracinik, J; Brawn, I, P; Brelier, B; Brooks, W; Brunet, S; Bucci, F; Casadei, D; Casado, P; Cerri, A; Charlton, D G; Childers, J T; Collins, N J; Conde Muino, P; Coura Torres, R; Cranmer, K; Curtis, C J; Czyczula, Z; Dam, M; Damazio, D; Davis, A O; De Santo, A; Degenhardt, J; Delsart, P A; Demers, S; Demirkoz, B; Di Mattia, A; Diaz, M; Djilkibaev, R; Dobson, E; Dova, M, T; Dufour, M A; Eckweiler, S; Ehrenfeld, W; Eifert, T; Eisenhandler, E; Ellis, N; Emeliyanov, D; Enoque Ferreira de Lima, D; Faulkner, P J W; Ferland, J; Flacher, H; Fleckner, J E; Flowerdew, M; Fonseca-Martin, T; Fratina, S; Fhlisch, F; Gadomski, S; Gallacher, M P; Garitaonandia Elejabarrieta, H; Gee, C N P; George, S; Gillman, A R; Goncalo, R; Grabowska-Bold, I; Groll, M; Gringer, C; Hadley, D R; Haller, J; Hamilton, A; Hanke, P; Hauser, R; Hellman, S; Hidvgi, A; Hillier, S J; Hryn'ova, T; Idarraga, J; Johansen, M; Johns, K; Kalinowski, A; Khoriauli, G; Kirk, J; Klous, S; Kluge, E-E; Koeneke, K; Konoplich, R; Konstantinidis, N; Kwee, R; Landon, M; LeCompte, T; Ledroit, F; Lei, X; Lendermann, V; Lilley, J N; Losada, M; Maettig, S; Mahboubi, K; Mahout, G; Maltrana, D; Marino, C; Masik, J; Meier, K; Middleton, R P; Mincer, A; Moa, T; Monticelli, F; Moreno, D; Morris, J D; Mller, F; Navarro, G A; Negri, A; Nemethy, P; Neusiedl, A; Oltmann, B; Olvito, D; Osuna, C; Padilla, C; Panes, B; Parodi, F; Perera, V J O; Perez, E; Perez Reale, V; Petersen, B; Pinzon, G; Potter, C; Prieur, D P F; Prokishin, F; Qian, W; Quinonez, F; Rajagopalan, S; Reinsch, A; Rieke, S; Riu, I; Robertson, S; Rodriguez, D; Rogriquez, Y; Rhr, F; Saavedra, A; Sankey, D P C; Santamarina, C; Santamarina Rios, C; Scannicchio, D; Schiavi, C; Schmitt, K; Schultz-Coulon, H C; Schfer, U; Segura, E; Silverstein, D; Silverstein, S; Sivoklokov, S; Sjlin, J; Staley, R J; Stamen, R; Stelzer, J; Stockton, M C; Straessner, A; Strom, D; Sushkov, S; Sutton, M; Tamsett, M; Tan, C L A; Tapprogge, S; Thomas, J P; Thompson, P D; Torrence, E; Tripiana, M; Urquijo, P; Urrejola, P; Vachon, B; Vercesi, V; Vorwerk, V; Wang, M; Watkins, P M; Watson, A; Weber, P; Weidberg, T; Werner, P; Wessels, M; Wheeler-Ellis, S; Whiteson, D; Wiedenmann, W; Wielers, M; Wildt, M; Winklmeier, F; Wu, X; Xella, S; Zhao, L; Zobernig, H; de Seixas, J M; dos Anjos, A; Asman, B; Özcan, E

2009-01-01

The ATLAS experiment is preparing for data taking at 14 TeV collision energy. A rich discovery physics program is being prepared in addition to the detailed study of Standard Model processes which will be produced in abundance. The ATLAS multi-level trigger system is designed to accept one event in 2 105 to enable the selection of rare and unusual physics events. The ATLAS calorimeter system is a precise instrument, which includes liquid Argon electro-magnetic and hadronic components as well as a scintillator-tile hadronic calorimeter. All these components are used in the various levels of the trigger system. A wide physics coverage is ensured by inclusively selecting events with candidate electrons, photons, taus, jets or those with large missing transverse energy. The commissioning of the trigger system is being performed with cosmic ray events and by replaying simulated Monte Carlo events through the trigger and data acquisition system.

The ATLAS Run-2 Trigger: Design, Menu, Performance and Operational Aspects

CERN Document Server

Martin, Tim; The ATLAS collaboration

2016-01-01

The LHC, at design capacity, has a bunch-crossing rate of 40 MHz whereas the ATLAS experiment at the LHC has an average recording rate of about 1000 Hz. To reduce the rate of events but still maintain a high efficiency of selecting rare events such as physics signals beyond the Standard Model, a two-level trigger system is used in ATLAS. Events are selected based on physics signatures such as presence of energetic leptons, photons, jets or large missing energy. Despite the limited time available for processing collision events, the trigger system is able to exploit topological information, as well as using multi-variate methods. In total, the ATLAS trigger system consists of thousands of different individual triggers. The ATLAS trigger menu specifies which triggers are used during data taking and how much rate a given trigger is allocated. This menu reflects not only the physics goals of the collaboration but also takes the instantaneous luminosity of the LHC, the design limits of the ATLAS detector and the o...

Two-photon transitions to exciton polaritons

International Nuclear Information System (INIS)

Hassan, A.R.

1979-08-01

A semiclassical theory for the creation of excitonic polariton states by two-photon absorption, via an intermediate exciton state, is given. A band model has been introduced which gives the dominant contribution to this process. A numerical calculation is found to be in good agreement with a recent observation in CuCl. (author)

Two-photon Doppler cooling of alkaline-earth-metal and ytterbium atoms

International Nuclear Information System (INIS)

Magno, Wictor C.; Cavasso Filho, Reinaldo L.; Cruz, Flavio C.

2003-01-01

The possibility of laser cooling of alkaline-earth-metal atoms and ytterbium atoms using a two-photon transition is analyzed. We consider a 1 S 0 - 1 S 0 transition with excitation in near resonance with the 1 P 1 level. This greatly increases the two-photon transition rate, allowing an effective transfer of momentum. The experimental implementation of this technique is discussed and we show that for calcium, for example, two-photon cooling can be used to achieve a Doppler limit of 123 μK. The efficiency of this cooling scheme and the main loss mechanisms are analyzed

Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

Science.gov (United States)

Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

1988-01-01

Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

Optimal enhancement in conversion efficiency of crystalline Si solar cells using inverse opal photonic crystals as back reflectors

International Nuclear Information System (INIS)

Chaouachi, A; M’nif, A; Hamzaoui, A H; Chtourou, R

2015-01-01

The effect of using inverse opal photonic crystals as back reflectors on the power conversion efficiency of c-Si solar cells is investigated. The reflection spectra of inverse opal photonic crystals with different diameters of air spheres are simulated using the finite difference time domain (FDTD) method. The reflection peaks are correlated with photonic band gaps present in the photonic band gap diagram. Significant improvement in the optical absorption of the crystalline silicon layer is recorded when inverse opal photonic crystals are considered. Physical mechanisms which may contribute to the enhancement of the light absorption are underlined. With higher short-circuit current enhancement possible, and with no corresponding degradation in open-circuit voltage V oc or the fill factor, the power conversion efficiency is increased significantly when inverse opal photonic crystals are used as back reflectors with optimized diameter of air spheres. (paper)

Two mechanisms of disorder-induced localization in photonic-crystal waveguides

Science.gov (United States)

García, P. D.; KiršanskÄ--, G.; Javadi, A.; Stobbe, S.; Lodahl, P.

2017-10-01

Unintentional but unavoidable fabrication imperfections in state-of-the-art photonic-crystal waveguides lead to the spontaneous formation of Anderson-localized modes thereby limiting slow-light propagation and its potential applications. On the other hand, disorder-induced cavities offer an approach to cavity-quantum electrodynamics and random lasing at the nanoscale. The key statistical parameter governing the disorder effects is the localization length, which together with the waveguide length determines the statistical transport of light through the waveguide. In a disordered photonic-crystal waveguide, the localization length is highly dispersive, and therefore, by controlling the underlying lattice parameters, it is possible to tune the localization of the mode. In the present work, we study the localization length in a disordered photonic-crystal waveguide using numerical simulations. We demonstrate two different localization regimes in the dispersion diagram where the localization length is linked to the density of states and the photon effective mass, respectively. The two different localization regimes are identified in experiments by recording the photoluminescence from quantum dots embedded in photonic-crystal waveguides.

Efficient fiber-coupled single-photon sources based on quantum dots

DEFF Research Database (Denmark)

Daveau, Raphaël Sura

refrigeration with coupled quantum wells. Many photonic quantum information processing applications would benet from a highbrightness, ber-coupled source of triggered single photons. This thesis presents a study of such sources based on quantum dots coupled to unidirectional photonic-crystal waveguide devices.......6 %. This latter method opens a promising future for increasing the eciency and reliability of planar chip-based single-photon sources. Refrigeration of a solid-state system with light has potential applications for cooling small-scale electronic and photonic circuits. We show theoretically that two coupled...... semiconductor quantum wells are ecient cooling media because they support long-lived indirect electron-hole pairs. These pairs can be thermally excited to distinct higher-energy states with faster radiative recombination, thereby creating an ecient escape channel to remove thermal energy from the system. From...

Multi-mode interference revealed by two photon absorption in silicon rich SiO2 waveguides

International Nuclear Information System (INIS)

Manna, S.; Ramiro-Manzano, F.; Mancinelli, M.; Turri, F.; Pavesi, L.; Ghulinyan, M.; Pucker, G.

2015-01-01

Photoluminescence (PL) from Si nanocrystals (NCs) excited by two-photon absorption (TPA) has been observed in Si nanocrystal-based waveguides fabricated by plasma enhanced chemical vapor deposition. The TPA excited photoluminescence emission resembles the one-photon excited photoluminescence arising from inter-band transitions in the quantum confined Si nanocrystals. By measuring the non-linear transmission of waveguides, a large TPA coefficient of β up to 10 −8  cm/W has been measured at 1550 nm. These values of β depend on the Si NCs size and are two orders of magnitude larger than the bulk silicon value. Here, we propose to use the TPA excited visible PL emission as a tool to map the spatial intensity profile of the 1550 nm propagating optical modes in multimode waveguides. In this way, multimode interference has been revealed experimentally and confirmed through a finite element simulation

Event-triggered Kalman-consensus filter for two-target tracking sensor networks.

Science.gov (United States)

Su, Housheng; Li, Zhenghao; Ye, Yanyan

2017-11-01

This paper is concerned with the problem of event-triggered Kalman-consensus filter for two-target tracking sensor networks. According to the event-triggered protocol and the mean-square analysis, a suboptimal Kalman gain matrix is derived and a suboptimal event-triggered distributed filter is obtained. Based on the Kalman-consensus filter protocol, all sensors which only depend on its neighbors' information can track their corresponding targets. Furthermore, utilizing Lyapunov method and matrix theory, some sufficient conditions are presented for ensuring the stability of the system. Finally, a simulation example is presented to verify the effectiveness of the proposed event-triggered protocol. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

Energy Technology Data Exchange (ETDEWEB)

Schlehahn, A.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin 10623 (Germany); Gaafar, M.; Vaupel, M.; Stolz, W.; Rahimi-Iman, A.; Koch, M. [Department of Physics and Materials Science Center, Philipps-Universität Marburg, 35032 Marburg (Germany)

2015-07-27

We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g{sup (2)}(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

Inclusive two-jet production in photon-photon collisions: Direct and resolved contributions in next-to-leading order QCD

International Nuclear Information System (INIS)

Kleinwort, T.; Kramer, G.

1996-10-01

We have calculated inclusive two-jet production in photon-photon collisions superimposing direct, single-resolved and double-resolved cross sections for center-of-mass energies of TRISTAN and LEP1.5. All three contributions are calculated up to next-to-leading order. The results are compared with recent experimental data. Three NLO sets of parton distributions of the photon are tested. (orig.)

Enhanced photoelectrochemical water splitting of BiVO4 photonic crystal photoanode by decorating with MoS2 nanosheets

Science.gov (United States)

Nan, Feng; Cai, Tianyi; Ju, Sheng; Fang, Liang

2018-04-01

Bismuth vanadate (BiVO4) has been considered as one of the promising Photoelectrochemical (PEC) photoanode materials. However, the performances remain poorly rated due to inefficient carrier separation, short carrier diffusion length, and sluggish water oxidation kinetics. Herein, a photoanode consisting of MoS2 nanosheet coating on the three-dimensional ordered BiVO4 inverse opal is fabricated by a facile combination of nanosphere lithography and hydrothermal methods. By taking advantage of the photonic crystal and two-dimensional material, the optimized MoS2/BiVO4 inverse opal photoanode exhibits a 560% improvement of the photocurrent density and threefold enhancement of the incident photon-to-current efficiency than that of the pristine BiVO4 film photoanode. Systematic studies reveal that the excellent PEC activity should be attributed to enhanced light harvesting and charge separation efficiency.

Two-photon polarization Fourier spectroscopy of metastable atomic hydrogen

International Nuclear Information System (INIS)

Duncan, A.J.; Beyer, H.-J.; Kleinpoppen, H.; Sheikh, Z.A,; B-Z Univ., Multan

1997-01-01

A novel Fourier-transform spectroscopic method using two-photon polarization to determine the spectral distribution of the two photons emitted in the spontaneous decay of metastable atomic hydrogen is described. The method uses birefringent retardation plates and takes advantage of the subtle interplay between the spectral properties and the entangled polarization properties of the radiation emitted in the decay. Assuming the validity of the theoretical spectral distribution, it is shown that the experimental results agree well with theory. On the other hand, success in solving the inverse problem of determining the spectral distribution from the experimental results is limited by the small number of experimental points. However, making reasonable assumptions it is deduced that the observed spectrum is characterized by a broadband signal of width (0.43 ± 0.06) x 10 16 rad s -1 and centre angular frequency (0.77 ± 0.03) x 10 16 rad s -1 in good agreement with the predictions of 0.489 x 10 16 rad s -1 and 0.775 x 10 16 rad s -1 , respectively, obtained from the theoretical spectral distribution modified to take account of the absorption of the two-photon radiation in air. The values of 1.5 fs for the coherence time and 440 nm for the coherence length for single photons of the two-photon pair which are obtained from the measured bandwidth imply that, in the ideal case, these values are determined by the essentially zero lifetime of the virtual intermediate state of the decay process rather than the long lifetime of the metastable state which, it is suggested, determines the coherence time and coherence length appropriate to certain types of fourth-order interference experiments. (Author)

Two-electron one-photon decay rates in doubly ionized atoms

International Nuclear Information System (INIS)

Baptista, G.B.

1984-01-01

The transion rate for the two-electron one-photon and one-electron one-photon decaying processes in atoms bearing initially two K-shell vacancies were evaluated for Ne up to Zr. The two-electron one-photon decay process is considered to be the result of the interaction between the jumping electrons and their interaction with the radiation field. The calculation is performed in second order perturbation theory and the many particle states are constructed from single particle solutions. The present approach allows one to discuss several aspects of the decaying process. The results obtained for the branching ratio between the two processes reproduces reasonably well available experimental data and show an almost linear dependence on the second power of the atomic number. A comparison with other theoretical predictions is also presented for the two decaying processes and the strong dependence of the branching ratio on the initial configuration of the decaying atom is pointed out. (Author) [pt

Time correlation in two-photon decay

International Nuclear Information System (INIS)

Hrasko, P.

1979-11-01

The relative time distribution of the photons emitted in a second order non-cascade process b→a+2γ is investigated under the assumption that only those photon pairs are detected which were emitted a sufficiently long time after the preparation of the decaying state. An anticorrelation between the photons is found and attributed to the propagation of one of the photons backward in time. (author)

Effect of Video Triggering During Conventional Lectures on Final Grades of Dental Students in an Oral Biology Course: A Two-Year Retrospective Study.

Science.gov (United States)

Farooq, Imran; Al-Jandan, Badr A

2015-12-01

The aim of this study was to analyze the effect of the inclusion of video triggers in conventional face-to-face lectures on the final grades of dental students in an oral biology course. The study consisted of two groups of students taking the course in two academic years at a dental school in Saudi Arabia: group 1, 2013-14 (control); and group 2, 2014-15. The total sample comprised 163 students (n=163; group 1: 71 and group 2: 92). Group 1 received lectures without any videos, whereas group 2 received lectures that included two to three videos of one to five minutes in duration with triggering effect (a video was shown every 10-15 minutes into the lecture). The final examination grades of the students were accessed retrospectively, and the data were compared with a chi-square test. The results confirmed that a higher number of students who received video triggering during lectures (group 2) performed better than their counterparts who did not receive video triggers (group 1); the difference was statistically significant (pvideo triggers may offer an advantage over conventional methods and their inclusion in lectures can be a way to enhance students' learning.

Photon activation therapy: a Monte Carlo study on dose enhancement by various sources and activation media

International Nuclear Information System (INIS)

Bakhshabadi, Mahdi; Ghorbani, Mahdi; Meigooni, Ali Soleimani

2013-01-01

In the present study, a number of brachytherapy sources and activation media were simulated using MCNPX code and the results were analyzed based on the dose enhancement factor values. Furthermore, two new brachytherapy sources ( 131 Cs and a hypothetical 170 Tm) were evaluated for their application in photon activation therapy (PAT). 125 I, 103 Pd, 131 Cs and hypothetical 170 Tm brachytherapy sources were simulated in water and their dose rate constant and the radial dose functions were compared with previously published data. The sources were then simulated in a soft tissue phantom which was composed of Ag, I, Pt or Au as activation media uniformly distributed in the tumour volume. These simulations were performed using the MCNPX code, and dose enhancement factor (DEF) was obtained for 7, 18 and 30 mg/ml concentrations of the activation media. Each source, activation medium and concentration was evaluated separately in a separate simulation. The calculated dose rate constant and radial dose functions were in agreement with the published data for the aforementioned sources. The maximum DEF was found to be 5.58 for a combination of the 170 Tm source with 30 mg/ml concentration of I. The DEFs for 131 Cs and 170 Tm sources for all the four activation media were higher than those for other sources and activation media. From this point of view, these two sources can be more useful in photon activation therapy with photon emitter sources. Furthermore, 131 Cs and 170 Tm brachytherapy sources can be proposed as new options for use in the field of PAT.

Entanglement dynamics of a double two-photon Jaynes–Cummings model with Kerr-like medium

International Nuclear Information System (INIS)

Xi-Cheng, Ouyang; Mao-Fa, Fang; Guo-Dong, Kang; Xiao-Juan, Deng; Li-Yuan, Huang

2010-01-01

In this paper, the entanglement dynamics of a double two-photon Jaynes–Cummings model with Kerr-like medium is investigated. It is shown that initial entanglement has an interesting subsequent time evolution, including the so-called entanglement sudden death effect. It is also shown analytically that the Kerr-like medium can repress entanglement sudden death and enhance the degree of atom-atom entanglement. A more interesting fact is that the Kerr effect is more obvious when each of the two cavities with have the Kerr-like medium than only one of them with the Kerr-like medium

Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

Energy Technology Data Exchange (ETDEWEB)

Foteinopoulou, Stavroula [Iowa State Univ., Ames, IA (United States)

2003-01-01

In this dissertation, they have undertaken the challenge to understand the unusual propagation properties of the photonic crystal (PC). The photonic crystal is a medium where the dielectric function is periodically modulated. These types of structures are characterized by bands and gaps. In other words, they are characterized by frequency regions where propagation is prohibited (gaps) and regions where propagation is allowed (bands). In this study they focus on two-dimensional photonic crystals, i.e., structures with periodic dielectric patterns on a plane and translational symmetry in the perpendicular direction. They start by studying a two-dimensional photonic crystal system for frequencies inside the band gap. The inclusion of a line defect introduces allowed states in the otherwise prohibited frequency spectrum. The dependence of the defect resonance state on different parameters such as size of the structure, profile of incoming source, etc., is investigated in detail. For this study, they used two popular computational methods in photonic crystal research, the Finite Difference Time Domain method (FDTD) and the Transfer Matrix Method (TMM). The results for the one-dimensional defect system are analyzed, and the two methods, FDTD and TMM, are compared. Then, they shift their attention only to periodic two-dimensional crystals, concentrate on their band properties, and study their unusual refractive behavior. Anomalous refractive phenomena in photonic crystals included cases where the beam refracts on the ''wrong'' side of the surface normal. The latter phenomenon, is known as negative refraction and was previously observed in materials where the wave vector, the electric field, and the magnetic field form a left-handed set of vectors. These materials are generally called left-handed materials (LHM) or negative index materials (NIM). They investigated the possibility that the photonic crystal behaves as a LHM, and how this behavior relates

Two-photon optics of Bessel-Gaussian modes

CSIR Research Space (South Africa)

McLaren, M

2013-09-01

Full Text Available In this paper we consider geometrical two-photon optics of Bessel-Gaussian modes generated in spontaneous parametric down-conversion of a Gaussian pump beam. We provide a general theoretical expression for the orbital angular momentum (OAM) spectrum...

Event-by-event simulation of nonclassical effects in two-photon interference experiments

NARCIS (Netherlands)

Michielsen, K.; Jin, F.; Delina, M.; Raedt, H. De

2012-01-01

A corpuscular simulation model for second-order intensity interference phenomena is discussed. It is shown that both the visibility V = 1/2 predicted for two-photon interference experiments with two independent sources and the visibility V = 1 predicted for two-photon interference experiments with a

Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels

Science.gov (United States)

Gogurla, Narendar; Sinha, Arun K.; Naskar, Deboki; Kundu, Subhas C.; Ray, Samit K.

2016-03-01

Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms.

Calorimetry triggering in ATLAS

International Nuclear Information System (INIS)

Igonkina, O; Achenbach, R; Andrei, V; Adragna, P; Aharrouche, M; Bauss, B; Bendel, M; Alexandre, G; Anduaga, X; Aracena, I; Backlund, S; Bogaerts, A; Baines, J; Barnett, B M; Bee, C; P, Behera; Bell, P; Benslama, K; Berry, T; Bohm, C

2009-01-01

The ATLAS experiment is preparing for data taking at 14 TeV collision energy. A rich discovery physics program is being prepared in addition to the detailed study of Standard Model processes which will be produced in abundance. The ATLAS multi-level trigger system is designed to accept one event in 2 | 10 5 to enable the selection of rare and unusual physics events. The ATLAS calorimeter system is a precise instrument, which includes liquid Argon electro-magnetic and hadronic components as well as a scintillator-tile hadronic calorimeter. All these components are used in the various levels of the trigger system. A wide physics coverage is ensured by inclusively selecting events with candidate electrons, photons, taus, jets or those with large missing transverse energy. The commissioning of the trigger system is being performed with cosmic ray events and by replaying simulated Monte Carlo events through the trigger and data acquisition system.

Calorimetry Triggering in ATLAS

International Nuclear Information System (INIS)

Igonkina, O.; Achenbach, R.; Adragna, P.; Aharrouche, M.; Alexandre, G.; Andrei, V.; Anduaga, X.; Aracena, I.; Backlund, S.; Baines, J.; Barnett, B.M.; Bauss, B.; Bee, C.; Behera, P.; Bell, P.; Bendel, M.; Benslama, K.; Berry, T.; Bogaerts, A.; Bohm, C.; Bold, T.; Booth, J.R.A.; Bosman, M.; Boyd, J.; Bracinik, J.; Brawn, I.P.; Brelier, B.; Brooks, W.; Brunet, S.; Bucci, F.; Casadei, D.; Casado, P.; Cerri, A.; Charlton, D.G.; Childers, J.T.; Collins, N.J.; Conde Muino, P.; Coura Torres, R.; Cranmer, K.; Curtis, C.J.; Czyczula, Z.; Dam, M.; Damazio, D.; Davis, A.O.; De Santo, A.; Degenhardt, J.

2011-01-01

The ATLAS experiment is preparing for data taking at 14 TeV collision energy. A rich discovery physics program is being prepared in addition to the detailed study of Standard Model processes which will be produced in abundance. The ATLAS multi-level trigger system is designed to accept one event in 2/10 5 to enable the selection of rare and unusual physics events. The ATLAS calorimeter system is a precise instrument, which includes liquid Argon electro-magnetic and hadronic components as well as a scintillator-tile hadronic calorimeter. All these components are used in the various levels of the trigger system. A wide physics coverage is ensured by inclusively selecting events with candidate electrons, photons, taus, jets or those with large missing transverse energy. The commissioning of the trigger system is being performed with cosmic ray events and by replaying simulated Monte Carlo events through the trigger and data acquisition system.

Calorimetry triggering in ATLAS

Energy Technology Data Exchange (ETDEWEB)

Igonkina, O [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands); Achenbach, R; Andrei, V [Kirchhoff Institut fuer Physik, Universitaet Heidelberg, Heidelberg (Germany); Adragna, P [Physics Department, Queen Mary, University of London, London (United Kingdom); Aharrouche, M; Bauss, B; Bendel, M [Institut fr Physik, Universitt Mainz, Mainz (Germany); Alexandre, G [Section de Physique, Universite de Geneve, Geneva (Switzerland); Anduaga, X [Universidad Nacional de La Plata, La Plata (Argentina); Aracena, I [Stanford Linear Accelerator Center (SLAC), Stanford (United States); Backlund, S; Bogaerts, A [European Laboratory for Particle Physics (CERN), Geneva (Switzerland); Baines, J; Barnett, B M [STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon (United Kingdom); Bee, C [Centre de Physique des Particules de Marseille, IN2P3-CNRS, Marseille (France); P, Behera [Iowa State University, Ames, Iowa (United States); Bell, P [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); Benslama, K [University of Regina, Regina (Canada); Berry, T [Department of Physics, Royal Holloway and Bedford New College, Egham (United Kingdom); Bohm, C [Fysikum, Stockholm University, Stockholm (Sweden)

2009-04-01

The ATLAS experiment is preparing for data taking at 14 TeV collision energy. A rich discovery physics program is being prepared in addition to the detailed study of Standard Model processes which will be produced in abundance. The ATLAS multi-level trigger system is designed to accept one event in 2 | 10{sup 5} to enable the selection of rare and unusual physics events. The ATLAS calorimeter system is a precise instrument, which includes liquid Argon electro-magnetic and hadronic components as well as a scintillator-tile hadronic calorimeter. All these components are used in the various levels of the trigger system. A wide physics coverage is ensured by inclusively selecting events with candidate electrons, photons, taus, jets or those with large missing transverse energy. The commissioning of the trigger system is being performed with cosmic ray events and by replaying simulated Monte Carlo events through the trigger and data acquisition system.

Efficient multi-site two-photon functional imaging of neuronal circuits.

Science.gov (United States)

Castanares, Michael Lawrence; Gautam, Vini; Drury, Jack; Bachor, Hans; Daria, Vincent R

2016-12-01

Two-photon imaging using high-speed multi-channel detectors is a promising approach for optical recording of cellular membrane dynamics at multiple sites. A main bottleneck of this technique is the limited number of photons captured within a short exposure time (~1ms). Here, we implement temporal gating to improve the two-photon fluorescence yield from holographically projected multiple foci whilst maintaining a biologically safe incident average power. We observed up to 6x improvement in the signal-to-noise ratio (SNR) in Fluorescein and cultured hippocampal neurons showing evoked calcium transients. With improved SNR, we could pave the way to achieving multi-site optical recording of fluorogenic probes with response times in the order of ~1ms.

Two-photon fluorescence and fluorescence imaging of two styryl heterocyclic dyes combined with DNA.

Science.gov (United States)

Gao, Chao; Liu, Shu-yao; Zhang, Xian; Liu, Ying-kai; Qiao, Cong-de; Liu, Zhao-e

2016-03-05

Two new styryl heterocyclic two-photon (TP) materials, 4-[4-(N-methyl)styrene]-imidazo [4,5-f][1,10] phenanthroline-benzene iodated salt (probe-1) and 4,4-[4-(N-methyl)styrene]-benzene iodated salt (probe-2) were successfully synthesized and studied as potential fluorescent probes of DNA detection. The linear and nonlinear photophysical properties of two compounds in different solvents were investigated. The absorption, one- and two-photon fluorescent spectra of the free dye and dye-DNA complex were also examined to evaluate their photophysical properties. The binding constants of dye-DNA were obtained according to Scatchard equation with good values. The results showed that two probes could be used as fluorescent DNA probes by two-photon excitation, and TP fluorescent properties of probe-1 are superior to that of probe-2. The fluorescent method date indicated that the mechanisms of dye-DNA complex interaction may be groove binding for probe-1 and electrostatic interaction for probe-2, respectively. The MTT assay experiments showed two probes are low toxicity. Moreover, the TP fluorescence imaging of DNA detection in living cells at 800 nm indicated that the ability to locate in cell nuclei of probe-1 is better than that of probe-2. Copyright © 2015 Elsevier B.V. All rights reserved.

Particle Production in Two-Photon Collisions at Belle

International Nuclear Information System (INIS)

Nakazawa, Hideyuki

2010-01-01

Experimental study of η η production in two-photon collisions: The differential cross section for the process γ γ → η η has been measured in the kinematic range above the η η threshold, 1.096 GeV -1 data sample collected with the Belle detector at the KEKB e + e - collider. In the W range 1.1-2.0 GeV/c 2 we perform an analysis of resonance amplitudes for various partial waves; at higher energy we extract the contributions of χ cJ charmonia and compare the energy and angular dependence of the cross section with the predictions of theoretical models. Observation of η c (2S) in six-prong final states produced in two-photon collisions: We report the observation of η c (2S), produced in two-photon collisions, and decaying to the six-prong final states 3(π + π - ), K + K - 2(π + π - ), and K 0 S K + ππ + π - (including the charge-conjugate state). This analysis is based on a large data sample accumulated by the Belle experiment at the KEKB asymmetric-energy electron-positron collider. This is the first observation of decay modes of the η c (2S) other than K 0 S K + π - . (author)

Glass-embedded two-dimensional silicon photonic crystal devices with a broad bandwidth waveguide and a high quality nanocavity.

Science.gov (United States)

Jeon, Seung-Woo; Han, Jin-Kyu; Song, Bong-Shik; Noda, Susumu

2010-08-30

To enhance the mechanical stability of a two-dimensional photonic crystal slab structure and maintain its excellent performance, we designed a glass-embedded silicon photonic crystal device consisting of a broad bandwidth waveguide and a nanocavity with a high quality (Q) factor, and then fabricated the structure using spin-on glass (SOG). Furthermore, we showed that the refractive index of the SOG could be tuned from 1.37 to 1.57 by varying the curing temperature of the SOG. Finally, we demonstrated a glass-embedded heterostructured cavity with an ultrahigh Q factor of 160,000 by adjusting the refractive index of the SOG.

Smart detection of microRNAs through fluorescence enhancement on a photonic crystal.

Science.gov (United States)

Pasquardini, L; Potrich, C; Vaghi, V; Lunelli, L; Frascella, F; Descrovi, E; Pirri, C F; Pederzolli, C

2016-04-01

The detection of low abundant biomarkers, such as circulating microRNAs, demands innovative detection methods with increased resolution, sensitivity and specificity. Here, a biofunctional surface was implemented for the selective capture of microRNAs, which were detected through fluorescence enhancement directly on a photonic crystal. To set up the optimal biofunctional surface, epoxy-coated commercially available microscope slides were spotted with specific anti-microRNA probes. The optimal concentration of probe as well as of passivating agent were selected and employed for titrating the microRNA hybridization. Cross-hybridization of different microRNAs was also tested, resulting negligible. Once optimized, the protocol was adapted to the photonic crystal surface, where fluorescent synthetic miR-16 was hybridized and imaged with a dedicated equipment. The photonic crystal consists of a dielectric multilayer patterned with a grating structure. In this way, it is possible to take advantage from both a resonant excitation of fluorophores and an angularly redirection of the emitted radiation. As a result, a significant fluorescence enhancement due to the resonant structure is collected from the patterned photonic crystal with respect to the outer non-structured surface. The dedicated read-out system is compact and based on a wide-field imaging detection, with little or no optical alignment issues, which makes this approach particularly interesting for further development such as for example in microarray-type bioassays. Copyright © 2016 Elsevier B.V. All rights reserved.

A new two-photon mechanism of the formation of a continuous spectrum of photons emitted by secondary emission products of atomic particles

International Nuclear Information System (INIS)

Veksler, V.I.

1986-01-01

A two-photon mechanism of the formation of a continuous spectrum of photons emitted by products of metal sputtering is considered. The following process of the two-photon mechanism is considered: the continuous spectrum is formed under quadrupole two-photon transitions in sputtered excited atoms having vacancies at the d level in atoms of transition metals or at the of level in lanthanides found against the filled conduction band. It is shown that the suggested mechanism should play an essential role in the formation of the continuous spectrum of optical radiation

Photonic crystal light source

Science.gov (United States)

Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

2004-07-27

A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

Two-Photon Probes for Lysosomes and Mitochondria: Simultaneous Detection of Lysosomes and Mitochondria in Live Tissues by Dual-Color Two-Photon Microscopy Imaging.

Science.gov (United States)

Lim, Chang Su; Hong, Seung Taek; Ryu, Seong Shick; Kang, Dong Eun; Cho, Bong Rae

2015-10-01

Novel two-photon (TP) probes were developed for lysosomes (PLT-yellow) and mitochondria (BMT-blue and PMT-yellow). These probes emitted strong TP-excited fluorescence in cells at widely separated wavelength regions and displayed high organelle selectivity, good cell permeability, low cytotoxicity, and pH insensitivity. The BMT-blue and PLT-yellow probes could be utilized to detect lysosomes and mitochondria simultaneously in live tissues by using dual-color two-photon microscopy, with minimum interference from each other. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Broadband Doppler-limited two-photon and stepwise excitation spectroscopy with laser frequency combs

Science.gov (United States)

Hipke, Arthur; Meek, Samuel A.; Ideguchi, Takuro; Hänsch, Theodor W.; Picqué, Nathalie

2014-07-01

Multiplex two-photon excitation spectroscopy is demonstrated at Doppler-limited resolution. We describe first Fourier-transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb technique. Each transition is uniquely identified by the modulation imparted by the interfering comb excitations. The temporal modulation of the spontaneous two-photon fluorescence is monitored with a single photodetector, and the spectrum of all excited transitions is revealed by a Fourier transform.

One-dimensional modulation instability in biased two-photon photorefractive-photovoltaic crystals

International Nuclear Information System (INIS)

Zhan Kaiyun; Hou Chunfeng; Li Xin

2010-01-01

The one-dimensional modulation instability of broad optical beams in biased two-photon photorefractive-photovoltaic crystals is investigated under steady-state conditions. Our analysis indicates that the modulation instability growth rate depends on the external bias field, the bulk photovoltaic effect and the ratio of the intensity of the incident beam to that of the dark irradiance. Moreover, our results show that this modulation instability growth rate is the same as that in two-photon photorefractive-photovoltaic crystals under open circuit conditions in the absence of an external bias field, and the modulation instability growth rate in two-photon biased photorefractive-nonphotovoltaic crystals can be predicted when the bulk photovoltaic effect is neglected.

Expectations for direct photon physics from Fermilab experiment E705

International Nuclear Information System (INIS)

Wagoner, D.E.; Arenton, M.; Chen, T.Y.

1987-11-01

The E705 scintillation glass/lead glass electromagnetic calorimeter is described. The trigger used for recording high transverse momentum direct photon signals from 300 GeV/c π/sup /minus//, π + , /bar p/, p interactions in a Li 7 target is explained. Preliminary results on the response of this direct photon trigger and electromagnetic calorimeter and expected event sensitivities are presented. 14 refs., 9 figs., 2 tabs

Correlated two-photon interference in a dual-beam Michelson interferometer

International Nuclear Information System (INIS)

Kwiat, P.G.; Vareka, W.A.; Hong, C.K.; Nathel, H.; Chiao, R.Y.

1990-01-01

We report on an interference effect arising from a two-photon entangled state produced in a potassium dihydrogen phosphate (KDP) crystal pumped by an ultraviolet argon-ion laser. Two conjugate beams of signal and idler photons were injected in a parallel configuration into a single Michelson interferometer, and detected separately by two photomultipliers, while the difference in its arm lengths was slowly scanned. The coincidence rate exhibited fringes with a visibility of nearly 50%, and a period given by half the ultraviolet (not the signal or idler) wavelength, while the singles rate exhibited no fringes

Pressure broadening of atomic oxygen two-photon absorption laser induced fluorescence

NARCIS (Netherlands)

Marinov, D.; Drag, C.; Blondel, C.; Guaitella, O.; Golda, J.; Klarenaar, B.L.M.; Engeln, R.A.H.; Schulz-von der Gathen, V.; Booth, J.-P.

2016-01-01

Atomic oxygen, considered to be a determining reactant in plasma applications at ambient pressure, is routinely detected by two-photon absorption laser induced fluorescence (TALIF). Here, pressure broadening of the (2p 4 3 P 2  →  3p 3 P J=0,1,2) two-photon transition in oxygen atoms was

High-capacity quantum secure direct communication with two-photon six-qubit hyperentangled states

Science.gov (United States)

Wu, FangZhou; Yang, GuoJian; Wang, HaiBo; Xiong, Jun; Alzahrani, Faris; Hobiny, Aatef; Deng, FuGuo

2017-12-01

This study proposes the first high-capacity quantum secure direct communication (QSDC) with two-photon six-qubit hyper-entangled Bell states in two longitudinal momentum and polarization degrees of freedom (DOFs) of photon pairs, which can be generated using two 0.5 mm-thick type-I β barium borate crystal slabs aligned one behind the other and an eight-hole screen. The secret message can be independently encoded on the photon pairs with 64 unitary operations in all three DOFs. This protocol has a higher capacity than previous QSDC protocols because each photon pair can carry 6 bits of information, not just 2 or 4 bits. Our QSDC protocol decreases the influence of decoherence from environment noise by exploiting the decoy photons to check the security of the transmission of the first photon sequence. Compared with two-way QSDC protocols, our QSDC protocol is immune to an attack by an eavesdropper using Trojan horse attack strategies because it is a one-way quantum communication. The QSDC protocol has good applications in the future quantum communication because of all these features.

Two-Photon Rabi Splitting in a Coupled System of a Nanocavity and Exciton Complexes

Science.gov (United States)

Qian, Chenjiang; Wu, Shiyao; Song, Feilong; Peng, Kai; Xie, Xin; Yang, Jingnan; Xiao, Shan; Steer, Matthew J.; Thayne, Iain G.; Tang, Chengchun; Zuo, Zhanchun; Jin, Kuijuan; Gu, Changzhi; Xu, Xiulai

2018-05-01

Two-photon Rabi splitting in a cavity-dot system provides a basis for multiqubit coherent control in a quantum photonic network. Here we report on two-photon Rabi splitting in a strongly coupled cavity-dot system. The quantum dot was grown intentionally large in size for a large oscillation strength and small biexciton binding energy. Both exciton and biexciton transitions couple to a high-quality-factor photonic crystal cavity with large coupling strengths over 130 μ eV . Furthermore, the small binding energy enables the cavity to simultaneously couple with two exciton states. Thereby, two-photon Rabi splitting between the biexciton and cavity is achieved, which can be well reproduced by theoretical calculations with quantum master equations.

Efficient Entanglement Concentration of Nonlocal Two-Photon Polarization-Time-Bin Hyperentangled States

Science.gov (United States)

Wang, Zi-Hang; Yu, Wen-Xuan; Wu, Xiao-Yuan; Gao, Cheng-Yan; Alzahrani, Faris; Hobiny, Aatef; Deng, Fu-Guo

2018-03-01

We present two different hyperentanglement concentration protocols (hyper-ECPs) for two-photon systems in nonlocal polarization-time-bin hyperentangled states with known parameters, including Bell-like and cluster-like states, resorting to the parameter splitting method. They require only one of two parties in quantum communication to operate her photon in the process of entanglement concentration, not two, and they have the maximal success probability. They work with linear optical elements and have good feasibility in experiment, especially in the case that there are a big number of quantum data exchanged as the parties can obtain the information about the parameters of the nonlocal hyperentangled states by sampling a subset of nonlocal hyperentangled two-photon systems and measuring them. As the quantum state of photons in the time-bin degree of freedom suffers from less noise in an optical-fiber channel, these hyper-ECPs may have good applications in practical long-distance quantum communication in the future.

Reliability model analysis and primary experimental evaluation of laser triggered pulse trigger

International Nuclear Information System (INIS)

Chen Debiao; Yang Xinglin; Li Yuan; Li Jin

2012-01-01

High performance pulse trigger can enhance performance and stability of the PPS. It is necessary to evaluate the reliability of the LTGS pulse trigger, so we establish the reliability analysis model of this pulse trigger based on CARMES software, the reliability evaluation is accord with the statistical results. (authors)

The performance of the ATLAS Level-1 Calorimeter Trigger with LHC collision data

CERN Document Server

Bracinik, J

2011-01-01

The ATLAS first-level calorimeter trigger is a hardware-based system designed to identify high-E$_T$ jets, electron/photon and $ au$ candidates and to measure total and missing E$_T$ in the ATLAS calorimeters. After more than two years of commissioning in situ with calibration data and cosmic rays, the system has now been used extensively to select the most interesting proton-proton collision events. Fine tuning of timing and energy calibration has been carried out in 2010 to improve the trigger response to physics objects. In these proceedings, an analysis of the performance of the level-1 calorimeter trigger is presented, along with the techniques used to achieve these results.

Enhanced photothermal lens using a photonic crystal surface

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yunfei; Liu, Longju [Department of Electrical and Computer Engineering, 2128 Coover Hall, Iowa State University, Ames,Iowa 50011 (United States); Zhao, Xiangwei [State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering,Southeast University, Nanjing, Jiangsu 211189 (China); Lu, Meng, E-mail: menglu@iastate.edu [Department of Electrical and Computer Engineering, 2128 Coover Hall, Iowa State University, Ames,Iowa 50011 (United States); Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

2016-08-15

A photonic crystal (PC)-enhanced photothermal lens (PTL) is demonstrated for the detection of optically thin light absorption materials. The PC-enhanced PTL system is based on a pump-probe scheme consisting of a PC surface, pump laser beam, and probe laser beam. Heated by the pump beam, light absorption materials on the PC surface generate the PTL and cause a substantial change to the guided-mode resonance supported by the PC structure. The change of the PC resonance is detected using the probe laser beam by measuring its reflectivity from the PC surface. When applied to analyze dye molecules deposited on the PC substrate, the developed system is capable of enhancing the PTL signal by 10-fold and reducing the lowest distinguishable concentration by 8-fold, in comparison to measuring without utilizing the PC resonance. The PC-enhanced PTL was also used to detect gold nanoparticles on the PC surface and exhibited a 20-fold improvement of the lowest distinguishable concentration. The PC-enhanced PTL technology offers a potential tool to obtain the absorption signatures of thin films in a broad spectral range with high sensitivity and inexpensive instrumentation. As a result, this technology will enable a broad range of applications of photothermal spectroscopy in chemical analysis and biomolecule sensing.

New two-photon based nanoscopic modalities and optogenetics

DEFF Research Database (Denmark)

Glückstad, Jesper

that can be equipped with optical trapping handles for convenient mechanical control using only optical forces [6]. These microstructures illustrated above can be effectively handled with simultaneous top- and side-view on our BioPhotonics Workstation to undertake six-degree-of-freedom optical actuation...... of two-photon polymerised microstructures equipped with features easily entering the submicron-regime. Aided by European collaborators who fabricated test structures with built-in waveguides for us, we were able to put the idea of optically steerable freestanding waveguides – coined: wave-guided optical...

Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides

Science.gov (United States)

Yan, Siqi; Zhu, Xiaolong; Frandsen, Lars Hagedorn; Xiao, Sanshui; Mortensen, N. Asger; Dong, Jianji; Ding, Yunhong

2017-01-01

Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light–matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally demonstrate an energy-efficient graphene microheater with a tuning efficiency of 1.07 nmmW−1 and power consumption per free spectral range of 3.99 mW. The rise and decay times (10–90%) are only 750 and 525 ns, which, to the best of our knowledge, are the fastest reported response times for microheaters in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines for enhancing the tuning efficiency of the graphene microheater. PMID:28181531

The ATLAS Run-2 Trigger Menu for higher luminosities: Design, Performance and Operational Aspects

CERN Document Server

Ruiz-Martinez, Aranzazu; The ATLAS collaboration

2017-01-01

The ATLAS experiment aims at recording about 1 kHz of physics collisions, starting with an LHC design bunch crossing rate of 40 MHz. To reduce the massive background rate while maintaining a high selection efficiency for rare physics events (such as beyond the Standard Model physics), a two-level trigger system is used. Events are selected based on physics signatures such as presence of energetic leptons, photons, jets or large missing energy. The trigger system exploits topological information, as well as multi-variate methods to carry out the necessary physics filtering. In total, the ATLAS online selection consists of thousands of different individual triggers. A trigger menu is a compilation of these triggers which specifies the physics algorithms to be used during data taking and the bandwidth a given trigger is allocated. Trigger menus reflect not only the physics goals of the collaboration for a given run, but also take into consideration the instantaneous luminosity of the LHC and limitations from the...

The ATLAS Run-2 Trigger Menu for higher luminosities: Design, Performance and Operational Aspects

CERN Document Server

Torro Pastor, Emma; The ATLAS collaboration

2018-01-01

The ATLAS experiment aims at recording about 1 kHz of physics collisions, starting with an LHC design bunch crossing rate of 40 MHz. To reduce the massive background rate while maintaining a high selection efficiency for rare physics events (such as beyond the Standard Model physics), a two-level trigger system is used. Events are selected based on physics signatures such as presence of energetic leptons, photons, jets or large missing energy. The trigger system exploits topological information, as well as multi-variate methods to carry out the necessary physics filtering. In total, the ATLAS online selection consists of thousands of different individual triggers. A trigger menu is a compilation of these triggers which specifies the physics algorithms to be used during data taking and the bandwidth a given trigger is allocated. Trigger menus reflect not only the physics goals of the collaboration for a given run, but also take into consideration the instantaneous luminosity of the LHC and limitations from the...

The ATLAS Run-2 Trigger Menu for higher luminosities: Design, Performance and Operational Aspects

CERN Document Server

Montejo Berlingen, Javier; The ATLAS collaboration

2017-01-01

The LHC, at design capacity, has a bunch-crossing rate of 40 MHz whereas the ATLAS experiment has an average recording rate of about 1 kHz. To reduce the rate of events, but maintain high selection efficiency for rare events such as physics signals beyond the Standard Model, a two-level trigger system is used. Events are selected based on physics signatures such as presence of energetic leptons, photons, jets or large missing energy. Despite the limited time available for processing collision events the trigger system is able to exploit topological information, as well as using multi-variate methods. In total, the ATLAS trigger systems consists of thousands of different individual triggers. The ATLAS trigger menu specifies which triggers are used during data taking and how much rate a given trigger is allocated. This menu reflects not only the physics goals of the collaboration but also takes into consideration the instantaneous luminosity of the LHC and the design limits of the ATLAS detector and offline pro...

Influence of Two Photon Absorption on Soliton Self-Frequency Shift

DEFF Research Database (Denmark)

Steffensen, Henrik; Rottwitt, Karsten; Jepsen, Peter Uhd

2011-01-01

The creation of mid-infrared supercontinua necessitates the use of soft-glass fibers. However, some materials, like chalcogenide, have a substantial two photon absorption. We introduce a model for soliton self-frequency shift that successfully includes this effect.......The creation of mid-infrared supercontinua necessitates the use of soft-glass fibers. However, some materials, like chalcogenide, have a substantial two photon absorption. We introduce a model for soliton self-frequency shift that successfully includes this effect....

Unambiguous modification of nonorthogonal single- and two-photon polarization states

International Nuclear Information System (INIS)

Torres-Ruiz, F. A.; Aguirre, J.; Delgado, A.; Lima, G.; Neves, L.; Roa, L.; Saavedra, C.; Padua, S.

2009-01-01

In this paper we propose a probabilistic method which allows an unambiguous modification of two nonorthogonal quantum states. We experimentally implement this protocol by using two-photon polarization states generated in the process of spontaneous parametric down conversion. In the experiment, for codifying initial quantum states, we consider single-photon states and heralded detection. We show that the application of this protocol to entangled states allows a fine control of the amount of entanglement of the initial state.

An R&D programme on alternative technologies for the ATLAS level-1 calorimeter trigger

CERN Document Server

Appelquist, G; Bohm, C; Engström, M; Hellman, S; Holmgren, S O; Johansson, E; Yamdagni, N; Zhao, X; Sundblad, R; Ödmark, A; Bodo, P; Elderstig, H; Hentzell, H; Lindgren, S; Tober, M; Johansson, H; Svensson, C; Yuan, J R; Mohktari, M; Ellis, Nick

1995-01-16

This note describes a first-level calorimeter trigger processor designed to take advantage of new possibilities that arise as a consequence of modern design techniques and components such as optical interconnections, application specific integrated circuits (ASICs) and multi-chip modules (MCMs). The design is homogeneous down to the trigger cell level. This means that no boundary effects occur due to the system partitioning. The construction presented relies mainly on two different types of highly complex ASICs for processing and an MCM for opto-electrical conversion of input data. The trigger processor performs electron/photon identification, jet detection and missing ET calculations for the central first-level trigger and region of interest (RoI) selection for the second-level trigger. Exploring the possibilities given by advanced technologies leads to a first-level trigger architecture with advantages over more traditional designs, allowing, for example, higher precision calculations. Remaining degrees of ...

Inhibition of two-photon absorption due to dipole-dipole interaction in nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7 (Canada)], E-mail: msingh@uwo.ca

2008-07-21

We have investigated the inhibition of two-photon absorption in photonic crystals doped with an ensemble of four-level nanoparticles. The particles are interacting with one another by the dipole-dipole interaction. Dipoles in nanoparticles are induced by a selected transition. Numerical simulations have been performed for an isotropic photonic crystal. Interesting phenomena have been predicted such as the inhibition of the two-photon absorption due to the dipole-dipole interaction. It has also been found that the inhibition effect can be switched on and off by tuning a decay resonance energy within the energy band of the crystal. A theory of dressed states has been used to explain the results.

Crossed-coil detection of two-photon excited nuclear quadrupole resonance

Science.gov (United States)

Eles, Philip T.; Michal, Carl A.

2005-08-01

Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum nutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate ( ωQ = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.

Efficient non-linear two-photon effects from the Cesium 6D manifold

Science.gov (United States)

Haluska, Nathan D.; Perram, Glen P.; Rice, Christopher A.

2018-02-01

We report several non-linear process that occur when two-photon pumping the cesium 6D states. Cesium vapor possess some of the largest two-photon pump cross sections in nature. Pumping these cross sections leads to strong amplified spontaneous emission that we observe on over 17 lasing lines. These new fields are strong enough to couple with the pump to create additional tunable lines. We use a heat pipe with cesium densities of 1014 to 1016 cm-3 and 0 to 5 Torr of helium buffer gas. The cesium 6D States are interrogated by both high energy pulses and low power CW sources. We observe four-wave mixing, six-wave mixing, potential two-photon lasing, other unknown nonlinear processes, and the persistence of some processes at low thresholds. This system is also uniquely qualified to support two-photon lasing under the proper conditions.

Photonic density of states of two-dimensional quasicrystalline photonic structures

International Nuclear Information System (INIS)

Jia Lin; Bita, Ion; Thomas, Edwin L.

2011-01-01

A large photonic band gap (PBG) is highly favorable for photonic crystal devices. One of the most important goals of PBG materials research is identifying structural design strategies for maximizing the gap size. We provide a comprehensive analysis of the PBG properties of two-dimensional (2D) quasicrystals (QCs), where rotational symmetry, dielectric fill factor, and structural morphology were varied systematically in order to identify correlations between structure and PBG width at a given dielectric contrast (13:1, Si:air). The transverse electric (TE) and transverse magnetic (TM) PBGs of 12 types of QCs are investigated (588 structures). We discovered a 12mm QC with a 56.5% TE PBG, the largest reported TE PBG for an aperiodic crystal to date. We also report here a QC morphology comprising ''throwing star''-like dielectric domains, with near-circular air cores and interconnecting veins emanating radially around the core. This interesting morphology leads to a complete PBG of ∼20% , which is the largest reported complete PBG for aperiodic crystals.

Single-organelle tracking by two-photon conversion

Science.gov (United States)

Watanabe, Wataru; Shimada, Tomoko; Matsunaga, Sachihiro; Kurihara, Daisuke; Fukui, Kiichi; Shin-Ichi Arimura, Shin-Ichi; Tsutsumi, Nobuhiro; Isobe, Keisuke; Itoh, Kazuyoshi

2007-03-01

Spatial and temporal information about intracellular objects and their dynamics within a living cell are essential for dynamic analysis of such objects in cell biology. A specific intracellular object can be discriminated by photoactivatable fluorescent proteins that exhibit pronounced light-induced spectral changes. Here, we report on selective labeling and tracking of a single organelle by using two-photon conversion of a photoconvertible fluorescent protein with near-infrared femtosecond laser pulses. We performed selective labeling of a single mitochondrion in a living tobacco BY-2 cell using two-photon photoconversion of Kaede. Using this technique, we demonstrated that, in plants, the directed movement of individual mitochondria along the cytoskeletons was mediated by actin filaments, whereas microtubules were not required for the movement of mitochondria. This single-organelle labeling technique enabled us to track the dynamics of a single organelle, revealing the mechanisms involved in organelle dynamics. The technique has potential application in direct tracking of selective cellular and intracellular structures.

A spirobifluorene-based two-photon fluorescence probe for mercury ions and its applications in living cells

Energy Technology Data Exchange (ETDEWEB)

Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn; Zhang, Yanzhen; Zhang, Wu; Li, Shaozhi; Tan, Jingjing; Han, Zhongying

2017-05-01

A novel spirobifluorene derivative SPF-TMS, which containing dithioacetal groups and triphenylamine units, was synthesized. The probing behaviors toward various metal ions were investigated via UV/Vis absorption spectra as well as one-photon fluorescence changes. The results indicated that SPF-TMS exhibits high sensitivity and selectivity for mercury ions. The detection limit was at least 8.6 × 10{sup −8}M, which is excellent comparing with other optical sensors for Hg{sup 2+}. When measured by two-photon excited fluorescence technique in THF at 800 nm, the two-photon cross-section of SPF-TMS is 272 GM. Especially, upon reaction with mercury species, SPF-TMS yielded another two-photon dye SPF-DA. Both SPF-TMS and SPF-DA emit strong two-photon induced fluorescence and can be applied in cell imaging by two-photon microscopy. - Highlights: • We report a spirobifluorene-based molecule as two-photon fluorescent probe with large two-photon cross-section. • The molecule has exclusive selectivity and sensitivity for mercury species. • The molecule has large two-photon emission changes before and after addition of Hg{sup 2+}. • Both the probe and the mercury ion-promoted reaction product can be applied in cell imaging by two-photon microscopy.

Accidental degeneracy in photonic bands and topological phase transitions in two-dimensional core-shell dielectric photonic crystals.

Science.gov (United States)

Xu, Lin; Wang, Hai-Xiao; Xu, Ya-Dong; Chen, Huan-Yang; Jiang, Jian-Hua

2016-08-08

A simple core-shell two-dimensional photonic crystal is studied where the triangular lattice symmetry and the C6 point group symmetry give rich physics in accidental touching points of photonic bands. We systematically evaluate different types of accidental nodal points at the Brillouin zone center for transverse-magnetic harmonic modes when the geometry and permittivity of the core-shell material are continuously tuned. The accidental nodal points can have different dispersions and topological properties (i.e., Berry phases). These accidental nodal points can be the critical states lying between a topological phase and a normal phase of the photonic crystal. They are thus very important for the study of topological photonic states. We show that, without breaking time-reversal symmetry, by tuning the geometry of the core-shell material, a phase transition into the photonic quantum spin Hall insulator can be achieved. Here the "spin" is defined as the orbital angular momentum of a photon. We study the topological phase transition as well as the properties of the edge and bulk states and their application potentials in optics.

The bremsstrahlung tagged photon beam in Hall B at JLab

CERN Document Server

Sober, D I; Longhi, A; Matthews, S K; O'Brien, J T; Berman, B L; Briscoe, W J; Cole, P L; Connelly, J P; Dodge, W R; Murphy, L Y; Philips, S A; Dugger, M K; Lawrence, D; Ritchie, B G; Smith, E S; Lambert, J M; Anciant, E; Audit, G; Auger, T; Marchand, C; Klusman, M; Napolitano, J; Khandaker, M A; Salgado, C W; Sarty, A J

2000-01-01

We describe the design and commissioning of the photon tagging beamline installed in experimental Hall B at the Thomas Jefferson National Accelerator Facility (JLab). This system can tag photon energies over a range from 20% to 95% of the incident electron energy, and is capable of operation with beam energies up to 6.1 GeV. A single dipole magnet is combined with a hodoscope containing two planar arrays of plastic scintillators to detect energy-degraded electrons from a thin bremsstrahlung radiator. The first layer of 384 partially overlapping small scintillators provides photon energy resolution, while the second layer of 61 larger scintillators provides the timing resolution necessary to form a coincidence with the corresponding nuclear interaction triggered by the tagged photon. The definitions of overlap channels in the first counter plane and of geometric correlation between the two planes are determined using digitized time information from the individual counters. Auxiliary beamline devices are briefl...

Two photon emission by hydrogen-like atoms in high temperature plasmas

International Nuclear Information System (INIS)

Costescu, A.; Manzatu, I.; Dinu, C.; Mihailescu, I.N.

1981-08-01

New exact solutions and a rather simple polynomial expression of the power emitted in the two photon transition from a metastable 2s state to the ground state of a hydrogen-like atom were infered with the aid of the Coulomb Green's function method. It was shown that the two photon decay represents under certain circumstances a significant power loss mechanism. (authors)

Two-photon cooling of magnesium atoms

DEFF Research Database (Denmark)

Malossi, N.; Damkjær, S.; Hansen, P. L.

2005-01-01

A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system (3s2)S01¿(3s3p)P11 at 285.2nm followed by the (3s3p)P11¿(3s3d)D21 transition at 880.7nm . For the ladder system quantum coherence effects may become important. Combined with...... and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed....

All-optical femtosecond switch using two-photon absorption

International Nuclear Information System (INIS)

Yavuz, D. D.

2006-01-01

Utilizing a two-photon absorption scheme in an alkali-metal vapor cell, we suggest a technique where a strong laser beam switches off another laser beam of different wavelength in femtosecond time scales

Mid-infrared two-photon absorption in an extended-wavelength InGaAs photodetector

Science.gov (United States)

Piccardo, Marco; Rubin, Noah A.; Meadowcroft, Lauren; Chevalier, Paul; Yuan, Henry; Kimchi, Joseph; Capasso, Federico

2018-01-01

We investigate the nonlinear optical response of a commercial extended-wavelength In0.81Ga0.19As uncooled photodetector. Degenerate two-photon absorption in the mid-infrared range is observed using a quantum cascade laser emitting at λ = 4.5 μm as the excitation source. From the measured two-photon photocurrent signal, we extract a two-photon absorption coefficient β(2) = 0.6 ± 0.2 cm/MW, in agreement with the theoretical value obtained from the Eg-3 scaling law. Considering the wide spectral range covered by extended-wavelength InxGa1-xAs alloys, this result holds promise for applications based on two-photon absorption for this family of materials at wavelengths between 1.8 and 5.6 μm.

TRIGGER

CERN Multimedia

W. Smith from contributions of C. Leonidopoulos

2010-01-01

Level-1 Trigger Hardware and Software Since nearly all of the Level-1 (L1) Trigger hardware at Point 5 has been commissioned, activities during the past months focused on the fine-tuning of synchronization, particularly for the ECAL and the CSC systems, on firmware upgrades and on improving trigger operation and monitoring. Periodic resynchronizations or hard resets and a shortened luminosity section interval of 23 seconds were implemented. For the DT sector collectors, an automatic power-off was installed in case of high temperatures, and the monitoring capabilities of the opto-receivers and the mini-crates were enhanced. The DTTF and the CSCTF now have improved memory lookup tables. The HCAL trigger primitive logic implemented a new algorithm providing better stability of the energy measurement in the presence of any phase misalignment. For the Global Calorimeter Trigger, additional Source Cards have been manufactured and tested. Testing of the new tau, missing ET and missing HT algorithms is underw...

Inhibition of two-photon absorption in a three-level system with a pair of bichromatic fields

International Nuclear Information System (INIS)

Zou Jinhua; Hu Xiangming; Cheng Guangling; Li Xing; Du Dan

2005-01-01

We study two-photon absorption in a three-level ladder atomic system driven by a pair of bichromatic fields of equal frequency differences. The high-frequency component of one bichromatic field and the low-frequency component of the other are on two-photon resonance. The transition probability is calculated by employing the method of harmonic expansion and matrix inversion. Unexpectedly, when the sums of the phases of the different pairs of field components on the two-photon resonance are equal to each other, two-photon absorption is dramatically suppressed and the atomic system becomes transparent against two-photon absorption. Physically, due to dynamical Stark splitting, the two-photon transitions induced by the different pairs of field components experience different dressed states with phase difference of π. As a result, destructive interference occurs between the two pathways and leads to the inhibition of two-photon absorption

Two-photon physics at LEP

International Nuclear Information System (INIS)

Ginzburg, I.F.

1988-01-01

The two-photon production of hadrons in e + e - collisions e + e - →e + e - h from which the γγ→h cross sections are extracted is discussed. The common features of these processes are: hadrons move, as a rule, along e + e - beam axis, their total transverse momentum K perpendicular or perpendicular to is small; the total hadron energy is usually less than √S/2. Physical problems of soft processes, exotics, hard processes, semihard processes are considered. New possibilities of LEP, the most interesting and real are presented

Selective two-photon collagen crosslinking in situ measured by Brillouin microscopy (Conference Presentation)

Science.gov (United States)

Kwok, Sheldon J. J.; Kuznetsov, Ivan A.; Kim, Moonseok; Choi, Myunghwan; Scarcelli, Giuliano; Yun, Seok-Hyun

2017-02-01

Two-photon polymerization and crosslinking are commonly used methods for microfabrication of three-dimensional structures with applications spanning from photonic microdevices, drug delivery systems, to cellular scaffolds. However, the use of two-photon processes for precise, internal modification of biological tissues has not yet been reported. One of the major challenges has been a lack of appropriate tools to monitor and characterize crosslinked regions nondestructively. Here, we demonstrate spatially selective two-photon collagen crosslinking (2P-CXL) in intact tissue for the first time. Using riboflavin photosensitizer and femtosecond laser irradiation, we crosslinked a small volume of tissue within animal corneas. Collagen fiber orientations and photobleaching were characterized by second harmonic generation and two-photon fluorescence imaging, respectively. Using confocal Brillouin microscopy, we measured local changes in longitudinal mechanical moduli and visualized the cross-linked pattern without perturbing surrounding non-irradiated regions. 2P-CXL-induced tissue stiffening was comparable to that achieved with conventional one-photon CXL. Our results demonstrate the ability to selectively stiffen biological tissue in situ at high spatial resolution, with broad implications in ophthalmology, laser surgery, and tissue engineering.

Two narrow bandwidth photons interfering in an electromagnetically induced transparency (EIT) system

International Nuclear Information System (INIS)

Wang Fuyuan; Shi Baosen; Lu Xiaosong; Guo Guangcan

2008-01-01

In this paper, we have analysed in detail the quantum interference of the degenerate narrowband two-photon state by using a Mach–Zehnder interferometer, in which an electromagnetically induced transparency (EIT) medium is placed in one of two interfering beams. Our results clearly show that it is possible to coherently keep the quantum state at a single photon level in the EIT process, especially when the transparent window of the EIT medium is much larger than the bandwidth of the single photon. This shows that the EIT medium is possibly a kind of memory or repeater for the narrowband photons in the areas of quantum communication and quantum computer. This kind of experiment is feasible within the current technology

Probabilistic teleportation scheme of two-mode entangled photon states by using linear optic element

Institute of Scientific and Technical Information of China (English)

XIANG Shao-hua

2003-01-01

A scheme for teleporting two-mode entangled photon states with the successful probability 33.3% is proposed. In the scheme, the teleporte d qubit is two-mode photon entangled states, and two pairs of EPR pair are used as quantum channel between a sender and a receiver. This procedure is achieved by using two 50/50 symmetric beam splitters and four photon number detectors wit h the help of classical information.

Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

International Nuclear Information System (INIS)

Bergamaschi, Anna; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura

2011-01-01

The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems

Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

Energy Technology Data Exchange (ETDEWEB)

Bergamaschi, Anna, E-mail: anna.bergamaschi@psi.ch; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

2011-11-01

The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems.

Two-dimensional Kagome photonic bandgap waveguide

DEFF Research Database (Denmark)

Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou

2000-01-01

The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....

Effects of autoionizing states on two-photon double ionization of the H2 molecule

International Nuclear Information System (INIS)

Guan, Xiaoxu; Bartschat, Klaus; Schneider, Barry I; Koesterke, Lars

2014-01-01

Treating the effects of autoionizing intermediate states on two-photon double ionization (DI) of the H 2 molecule using time-dependent laser pulses is a significant computational challenge. Relatively long exposure times are critical to understanding the dynamics. Using the fixed-nuclei approximation, we demonstrate how the doubly excited states enhance the angle-integrated generalized cross sections in H 2 , and how they affect the angular distribution pattern of the ejected electrons. As the energy approaches the threshold for sequential DI, there is a sharp rise in the cross section due to virtual sequential ionization

Single-Photon Avalanche Diode with Enhanced NIR-Sensitivity for Automotive LIDAR Systems.

Science.gov (United States)

Takai, Isamu; Matsubara, Hiroyuki; Soga, Mineki; Ohta, Mitsuhiko; Ogawa, Masaru; Yamashita, Tatsuya

2016-03-30

A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25-132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50-180 cm.

Sensing for intracellular thiols by water-insoluble two-photon fluorescent probe incorporating nanogel

Energy Technology Data Exchange (ETDEWEB)

Guo, Xudong; Zhang, Xin; Wang, Shuangqing; Li, Shayu [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Hu, Rui, E-mail: hurui@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Li, Yi, E-mail: yili@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Guoqiang, E-mail: gqyang@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2015-04-15

Highlights: • A novel “turn-on” two-photon fluorescent probe based on a π-conjugated triarylboron luminogen was designed and synthesized. • Fast, selective and sensitive detection of biothiols in 100% aqueous solution by simply loaded on a nanogel. • Single-photon and two-photon fluorescent bioimaging of biothiols in NIH/3T3 fibroblasts. - Abstract: A novel “turn-on” two-photon fluorescent probe containing a π-conjugated triarylboron luminogen and a maleimide moiety DMDP-M based on the photo-induced electron transfer (PET) mechanism for biothiol detection was designed and synthesized. By simply loading the hydrophobic DMDP-M on a cross-linked Pluronic{sup ®} F127 nanogel (CL-F127), a probing system DMDP-M/CL-F127 was established, which shows quick response, high selectivity and sensitivity to cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous phase. The DMDP-M/CL-F127 system presented the fastest response to Cys with a rate constant of 0.56 min{sup −1}, and the detection limit to Cys was calculated to be as low as 0.18 μM. The DMDP-M/CL-F127 system has been successfully applied to the fluorescence imaging of biothiols in NIH/3T3 fibroblasts either with single-photon or two-photon excitation because of its high biocompatibility and cell-membrane permeability. The present work provides a general, simple and efficient strategy for the application of hydrophobic molecules to sensing biothiols in aqueous phase, and a novel sensing system for intracellular biothiols fitted for both single-photon and two-photon fluorescence imaging.

Studies of photoionization in liquids using a laser two-photon ionization conductivity technique

International Nuclear Information System (INIS)

Siomos, K.; Christophorou, L.G.

1981-01-01

One-photon ionization studies of solute molecules in a liquid medium are limited by the absorption of the host medium. A laser two-photon ionization (TPI) technique using a frequency tunable dye laser has been developed, whereby the photoionization threshold of a solute molecule was determined from the induced conductivity in the liquid medium under study due to electron-ion pair formation via two-photon ionization of the solute. The two-photon induced electron-ion current is measured as a function of the laser wavelength, lambda/sub laser/. In this paper, results are reported and discussed on the photoionization of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), pyrene and fluoranthene in liquid n-pentane

Negative refraction at infrared wavelengths in a two-dimensional photonic crystal

International Nuclear Information System (INIS)

Berrier, A.; Mulot, M.; Swillo, M.; Qiu, M.; Thylen, L.; Anand, S.; Talneau, A.

2004-01-01

We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area

Transcutaneous vagus nerve stimulation (tVNS) enhances conflict-triggered adjustment of cognitive control.

Science.gov (United States)

Fischer, Rico; Ventura-Bort, Carlos; Hamm, Alfons; Weymar, Mathias

2018-04-24

Response conflicts play a prominent role in the flexible adaptation of behavior as they represent context-signals that indicate the necessity for the recruitment of cognitive control. Previous studies have highlighted the functional roles of the affectively aversive and arousing quality of the conflict signal in triggering the adaptation process. To further test this potential link with arousal, participants performed a response conflict task in two separate sessions with either transcutaneous vagus nerve stimulation (tVNS), which is assumed to activate the locus coeruleus-noradrenaline (LC-NE) system, or with neutral sham stimulation. In both sessions the N2 and P3 event-related potentials (ERP) were assessed. In line with previous findings, conflict interference, the N2 and P3 amplitude were reduced after conflict. Most importantly, this adaptation to conflict was enhanced under tVNS compared to sham stimulation for conflict interference and the N2 amplitude. No effect of tVNS on the P3 component was found. These findings suggest that tVNS increases behavioral and electrophysiological markers of adaptation to conflict. Results are discussed in the context of the potentially underlying LC-NE and other neuromodulatory (e.g., GABA) systems. The present findings add important pieces to the understanding of the neurophysiological mechanisms of conflict-triggered adjustment of cognitive control.

Design, Fabrication, and Measurement of Two-Dimensional Photonic Crystal Slab Waveguides

International Nuclear Information System (INIS)

Chao, Zhang; Xuan, Tang; Xiao-Yu, Mao; Kai-Yu, Cui; Lei, Cao; Yi-Dong, Huang; Wei, Zhang; Jiang-De, Peng

2008-01-01

Two-dimensional photonic crystal slab waveguides on SOI wafer are designed and fabricated. Photonic band gap, band gap guided mode, and index guided mode are observed by measuring the transmission spectra. The experimental results are in good agreement with the theoretical ones

Gap deformation and classical wave localization in disordered two-dimensional photonic-band-gap materials

International Nuclear Information System (INIS)

Lidorikis, E.; Sigalas, M. M.; Economou, E. N.; Soukoulis, C. M.

2000-01-01

By using two ab initio numerical methods, we study the effects that disorder has on the spectral gaps and on wave localization in two-dimensional photonic-band-gap materials. We find that there are basically two different responses depending on the lattice realization (solid dielectric cylinders in air or vice versa), the wave polarization, and the particular form under which disorder is introduced. Two different pictures for the photonic states are employed, the ''nearly free'' photon and the ''strongly localized'' photon. These originate from the two different mechanisms responsible for the formation of the spectral gaps, i.e., multiple scattering and single scatterer resonances, and they qualitatively explain our results. (c) 2000 The American Physical Society

Broadband two-photon absorption cross sections of benzothiazole derivatives and benzobisthiazolium salts

Science.gov (United States)

Noskovičova, Eva; Lorenc, Dušan; Magdolen, Peter; Sigmundová, Ivica; Zahradník, Pavol; Velič, Dušan

2018-05-01

Two-photon absorption (TPA) cross sections of conjugated donor-π-acceptor dipolar structures containing benzothiazole or benzobisthiazolium moieties are determined in a broad spectral range from 700 nm to 1000 nm using two-photon induced fluorescence technique. The TPA cross section values range from 150 GM to 4600 GM. The largest values are observed in near-infrared region. The dipolar derivative of benzothiazole has the largest TPA cross section of 4600 GM at wavelength of 890 nm. A combination of the large TPA in the near-infrared region and the high emission quantum yield makes these compounds excellent candidates for two-photon fluorescence microscopy.

Theoretical analysis of enhanced light output from a GaN light emitting diode with an embedded photonic crystal

International Nuclear Information System (INIS)

Wen Feng; Liu Deming; Huang Lirong

2010-01-01

The enhancement of the light output of an embedded photonic crystal light emitting diode is investigated based on the finite-difference time-domain modeling. The embedded photonic crystal (PC) lattice type, multi-layer embedded PC, distance between the multiple quantum well and the embedded PC are studied. It is found that the embedded one dimensional PC can act as well as embedded two dimensional PCs. The emitted light flux in the up direction can be increased by a new kind of multi-layer embedded PC. Also, we show that the light output in the up direction for the LED with both surfaces and embedded PC could be as high as five times that of a conventional LED. (semiconductor devices)

Theoretical analysis of enhanced light output from a GaN light emitting diode with an embedded photonic crystal

Energy Technology Data Exchange (ETDEWEB)

Wen Feng; Liu Deming; Huang Lirong, E-mail: hlr5649@163.co [Wuhan National Laboratory for Optoelectronics, College of Opto-Electronics Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-10-15

The enhancement of the light output of an embedded photonic crystal light emitting diode is investigated based on the finite-difference time-domain modeling. The embedded photonic crystal (PC) lattice type, multi-layer embedded PC, distance between the multiple quantum well and the embedded PC are studied. It is found that the embedded one dimensional PC can act as well as embedded two dimensional PCs. The emitted light flux in the up direction can be increased by a new kind of multi-layer embedded PC. Also, we show that the light output in the up direction for the LED with both surfaces and embedded PC could be as high as five times that of a conventional LED. (semiconductor devices)

Sensitivity comparison of two L-alanine doped blends to different photon energies

International Nuclear Information System (INIS)

Chen, Felipe; Vega Ramirez, Jose; Nicolucci, Patricia; Baffa, Oswaldo

2008-01-01

Full text: Blends of L-alanine (85% weight proportion) with KI (10%) and with PbI 2 (10%), these last two compounds acting as dopants, and with PVA (5%) acting as binder, were prepared in water at 80 C degrees. A blend of pure L-alanine (95%) with PVA (5%) was also prepared. The three blends were irradiated with photon beams of different energies (120 kV, 60 Co and 10 MV) with a unique dose of 30 Gy to compare their sensitivities for those three energies. EPR spectra of the three irradiated blends were recorded in a K-Band spectrometer (24 GHz) taking aliquots of about 4 mg for each blend. The energy sensitivity of a blend was defined as the peak-to-peak amplitude of its EPR spectrum central line. For the 60 Co energy (1.25 MeV) the blends presented practically the same sensitivity indicating that the presence of the dopants does not affect the sensitivity of L-alanine. For 10 MV X-rays there was an increment (around 20% - 30 %) in sensitivity for the two L-alanine doped blends compared with the pure L-alanine blend (not doped). In the case of 120 kV X-rays, the blends ala+KI and ala+PbI 2 showed an increment of 10 and 20 times, respectively, more sensitivity than the pure L-alanine blend. It is concluded that the dopants KI and PbI 2 produce a great enhance of the L-alanine sensitivity to low-energy photons. For the same dopant's content (10%) in the blend, PbI 2 showed a better performance. These results encourage us to try to enhance the sensitivity of L-alanine even more increasing the dopant's content in the blend. Application of these L-alanine doped blends in the dosimetry in diagnostic radiology could be possible. (author)

Coherent enhancement of resonance-mediated multiphoton absorption

International Nuclear Information System (INIS)

Zhang, Shian; Zhang, Hui; Jia, Tianqing; Wang, Zugeng; Sun, Zhenrong

2010-01-01

In this paper, we theoretically investigate the coherent enhancement of resonance-mediated (2+2) four-photon absorption. It is found that by shaping the spectral phase with a π phase step, the resonance-mediated (2+2) four-photon transition probability can be enhanced. Furthermore, the coherent enhancement dependences on the detuning between the two two-photon absorptions, laser spectral bandwidth and laser centre frequency are explicitly discussed and analysed. We believe these theoretical results may play an important role in enhancing more complex resonance-mediated multiphoton absorption processes.

Inclusive two-photon reactions at TRISTAN

International Nuclear Information System (INIS)

Drees, M.

1995-01-01

After briefly reviewing past accomplishments of TRISTAN experiments in the field of inclusive two-photon reactions, I discuss open problems in the Monte Carlo simulation of such reactions. The main emphasis is on multiple scattering, i.e. events where at least two pairs of partons scatter within the same γγ collision to form at least four (mini)jets. The cross section for such events might just be observable at TRISTAN. While theoretical arguments for the existence of such events are strong, they have not yet been directly observed experimentally, thereby potentially opening a new opportunity for TRISTAN experiments. (author)

Measurement of two-photon production of the χc2

International Nuclear Information System (INIS)

Dominick, J.; Sanghera, S.; Shelkov, V.; Skwarnicki, T.; Stroynowski, R.; Volobouev, I.; Zadorozhny, P.; Artuso, M.; He, D.; Goldberg, M.; Horwitz, N.; Kennett, R.; Moneti, G.C.; Muheim, F.; Mukhin, Y.; Playfer, S.; Rozen, Y.; Stone, S.; Thulasidas, M.; Vasseur, G.; Zhu, G.; Bartelt, J.; Csorna, S.E.; Egyed, Z.; Jain, V.; Sheldon, P.; Akerib, D.S.; Barish, B.; Chadha, M.; Chan, S.; Cowen, D.F.; Eigen, G.; Miller, J.S.; O'Grady, C.; Urheim, J.; Weinstein, A.J.; Acosta, D.; Athanas, M.; Masek, G.; Paar, H.; Sivertz, M.; Bean, A.; Gronberg, J.; Kutschke, R.; Menary, S.; Morrison, R.J.; Nakanishi, S.; Nelson, H.N.; Nelson, T.K.; Richman, J.D.; Ryd, A.; Tajima, H.; Schmidt, D.; Sperka, D.; Witherell, M.S.; Procario, M.; Yang, S.; Balest, R.; Cho, K.; Daoudi, M.; Ford, W.T.; Johnson, D.R.; Lingel, K.; Lohner, M.; Rankin, P.; Smith, J.G.; Alexander, J.P.; Bebek, C.; Berkelman, K.; Besson, D.; Browder, T.E.; Cassel, D.G.; Cho, H.A.; Coffman, D.M.; Drell, P.S.; Ehrlich, R.; Galik, R.S.; Garcia-Sciveres, M.; Geiser, B.; Gittelman, B.; Gray, S.W.; Hartill, D.L.; Heltsley, B.K.; Jones, C.D.; Jones, S.L.; Kandaswamy, J.; Katayama, N.; Kim, P.C.; Kreinick, D.L.; Ludwig, G.S.; Masui, J.; Mevissen, J.; Mistry, N.B.; Ng, C.R.; Nordberg, E.; Ogg, M.; Patterson, J.R.; Peterson, D.; Riley, D.; Salman, S.; Sapper, M.; Worden, H.; Wuerthwein, F.; Avery, P.; Freyberger, A.; Rodriguez, J.; Stephens, R.; Yelton, J.; Cinabro, D.; Henderson, S.; Kinoshita, K.; Liu, T.; Saulnier, M.; Shen, F.; Wilson, R.; Yamamoto, H.; Ong, B.; Selen, M.; Sadoff, A.J.; Ammar, R.; Ball, S.; Baringer, P.; Coppage, D.; Copty, N.; Davis, R.; Hancock, N.; Kelly, M.; Kwak, N.; Lam, H.; Kubota, Y.; Lattery, M.; Nelson, J.K.; Patton, S.; Perticone, D.; Poling, R.; Savinov, V.; Schrenk, S.; Wang, R.; Alam, M.S.; Kim, I.J.; Nemati, B.; O'Neill, J.J.; Severini, H.; Sun, C.R.; Zoeller, M.M.; Crawford, G.; Daubenmeir, M.; Fulton, R.; Fujino, D.; Gan, K.K.; Honscheid, K.; Kagan, H.; Kass, R.; Lee, J.

1994-01-01

The CLEO II detector is used to search for the production of χ c2 states in two-photon interactions. We use the signature χ c2 →γJ/ψ→γl + l - with l=e,μ. Using 1.49 fb -1 of data taken with beam energies near 5.29 GeV, the two-photon width of the χ c2 is determined to be Γ(χ c2 →γγ)=1.08±0.30(stat)±0.26(syst) keV, in agreement with predictions from perturbative QCD

Deformed two-photon squeezed states in noncommutative space

International Nuclear Information System (INIS)

Zhang Jianzu

2004-01-01

Recent studies on nonperturbation aspects of noncommutative quantum mechanics explored a new type of boson commutation relations at the deformed level, described by deformed annihilation-creation operators in noncommutative space. This correlated boson commutator correlates different degrees of freedom, and shows an essential influence on dynamics. This Letter devotes to the development of formalism of deformed two-photon squeezed states in noncommutative space. General representations of deformed annihilation-creation operators and the consistency condition for the electromagnetic wave with a single mode of frequency in noncommunicative space are obtained. Two-photon squeezed states are studied. One finds that variances of the dimensionless Hermitian quadratures of the annihilation operator in one degree of freedom include variances in the other degree of freedom. Such correlations show the new feature of spatial noncommutativity and allow a deeper understanding of the correlated boson commutator

Symmetry adaptation in two-photon spectroscopy

International Nuclear Information System (INIS)

Kibler, M.

1991-11-01

Symmetry adaptation techniques are applied to the determination of the intensity of two-photon transitions for transition ions in finite symmetry environments. The case of intra-configurational transitions are discussed with some details and some results on inter-configurational transitions are briefly reported. In particular, for intra-configurational transitions, a model is described which takes into account the following ingredients: (symmetry, second- plus third-order mechanisms, S-, L- and J-mixings). (author) 20 refs

Hierarchical trigger of the ALICE calorimeters

CERN Document Server

Muller, Hans; Novitzky, Norbert; Kral, Jiri; Rak, Jan; Schambach, Joachim; Wang, Ya-Ping; Wang, Dong; Zhou, Daicui

2010-01-01

The trigger of the ALICE electromagnetic calorimeters is implemented in 2 hierarchically connected layers of electronics. In the lower layer, level-0 algorithms search shower energy above threshold in locally confined Trigger Region Units (TRU). The top layer is implemented as a single, global trigger unit that receives the trigger data from all TRUs as input to the level-1 algorithm. This architecture was first developed for the PHOS high pT photon trigger before it was adopted by EMCal also for the jet trigger. TRU units digitize up to 112 analogue input signals from the Front End Electronics (FEE) and concentrate their digital stream in a single FPGA. A charge and time summing algorithm is combined with a peakfinder that suppresses spurious noise and is precise to single LHC bunches. With a peak-to-peak noise level of 150 MeV the linear dynamic range above threshold spans from MIP energies at 215 up to 50 GeV. Local level-0 decisions take less than 600 ns after LHC collisions, upon which all TRUs transfer ...

Interfering Heralded Single Photons from Two Separate Silicon Nanowires Pumped at Different Wavelengths

Directory of Open Access Journals (Sweden)

Xiang Zhang

2016-08-01

Full Text Available Practical quantum photonic applications require on-demand single photon sources. As one possible solution, active temporal and wavelength multiplexing has been proposed to build an on-demand single photon source. In this scheme, heralded single photons are generated from different pump wavelengths in many temporal modes. However, the indistinguishability of these heralded single photons has not yet been experimentally confirmed. In this work, we achieve 88% ± 8% Hong–Ou–Mandel quantum interference visibility from heralded single photons generated from two separate silicon nanowires pumped at different wavelengths. This demonstrates that active temporal and wavelength multiplexing could generate indistinguishable heralded single photons.

Meson production in two-photon interactions at LHC energies

Energy Technology Data Exchange (ETDEWEB)

Da Silva, D. T.; Goncalves, V. P.; Sauter, W. K. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Campus Universitario UFPel, CP 354, 96010-900, Capao do Leao-RS (Brazil)

2013-03-25

The LHC opens a new kinematical regime at high energy, where several questions related to the description of the high-energy regime of the Quantum Chromodynamics (QCD) remain without satisfactory answers. Some open questions are the search for non-q-bar q resonances, the determination of the spectrum of q-bar q states and the identification of states with anomalous {gamma}{gamma} couplings. A possible way to study these problems is the study of meson production in two-photon interactions. In this contribution we calculate the meson production in two-photon interactions at LHC energies considering proton - proton collisions and estimate the total cross section for the production of the mesons {pi}, a, f, {eta} and {chi}.

Higgs Decay to Photons at Two Loops

International Nuclear Information System (INIS)

Fugel, F.

2007-01-01

The calculation of the two-loop corrections to the partial width of an intermediate-mass Higgs boson decaying into a pair of photons is reviewed. The main focus lies on the electroweak (EW) contributions. The sum of the EW corrections ranges from -4% to 0% for a Higgs mass between 100 GeV and 150 GeV, while the complete correction at two-loop order amounts to less than ± 1.5% in this regime. (author)

Performance of the ATLAS Trigger System in 2010

CERN Document Server

Aad, Georges; Abdallah, Jalal; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; Abramowicz, Halina; Abreu, Henso; Acerbi, Emilio; Acharya, Bobby Samir; Adams, David; Addy, Tetteh; Adelman, Jahred; Aderholz, Michael; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Akiyama, Kunihiro; Alam, Mohammad; Alam, Muhammad Aftab; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Aliyev, Magsud; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alviggi, Mariagrazia; Amako, Katsuya; Amaral, Pedro; Amelung, Christoph; Ammosov, Vladimir; Amorim, Antonio; Amorós, Gabriel; Amram, Nir; Anastopoulos, Christos; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Andrieux, Marie-Laure; Anduaga, Xabier; Angerami, Aaron; Anghinolfi, Francis; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonelli, Stefano; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoun, Sahar; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Archambault, John-Paul; Arfaoui, Samir; Arguin, Jean-Francois; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnault, Christian; Artamonov, Andrei; Artoni, Giacomo; Arutinov, David; Asai, Shoji; Asfandiyarov, Ruslan; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astbury, Alan; Astvatsatourov, Anatoli; Atoian, Grigor; Aubert, Bernard; Auerbach, Benjamin; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Austin, Nicholas; Avolio, Giuseppe; Avramidou, Rachel Maria; Axen, David; Ay, Cano; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Bachy, Gerard; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagnaia, Paolo; Bahinipati, Seema; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Mark; Baker, Sarah; Baltasar Dos Santos Pedrosa, Fernando; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barashkou, Andrei; Barbaro Galtieri, Angela; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Barrillon, Pierre; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Detlef; Bartsch, Valeria; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Battistoni, Giuseppe; Bauer, Florian; Bawa, Harinder Singh; Beare, Brian; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Begel, Michael; Behar Harpaz, Silvia; Behera, Prafulla; Beimforde, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellina, Francesco; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Ben Ami, Sagi; Benary, Odette; Benchekroun, Driss; Benchouk, Chafik; Bendel, Markus; Benedict, Brian Hugues; Benekos, Nektarios; Benhammou, Yan; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernardet, Karim; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Berry, Tracey; Bertin, Antonio; Bertinelli, Francesco; Bertolucci, Federico; Besana, Maria Ilaria; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bitenc, Urban; Black, Kevin; Blair, Robert; Blanchard, Jean-Baptiste; Blanchot, Georges; Blazek, Tomas; Blocker, Craig; Blocki, Jacek; Blondel, Alain; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bobrovnikov, Victor; Bocchetta, Simona Serena; Bocci, Andrea; Boddy, Christopher Richard; Boehler, Michael; Boek, Jennifer; Boelaert, Nele; Böser, Sebastian; Bogaerts, Joannes Andreas; Bogdanchikov, Alexander; Bogouch, Andrei; Bohm, Christian; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Bolnet, Nayanka Myriam; Bona, Marcella; Bondarenko, Valery; Boonekamp, Maarten; Boorman, Gary; Booth, Chris; Bordoni, Stefania; Borer, Claudia; Borisov, Anatoly; Borissov, Guennadi; Borjanovic, Iris; Borroni, Sara; Bos, Kors; Boscherini, Davide; Bosman, Martine; Boterenbrood, Hendrik; Botterill, David; Bouchami, Jihene; Boudreau, Joseph; Bouhova-Thacker, Evelina Vassileva; Boulahouache, Chaouki; Bourdarios, Claire; Bousson, Nicolas; Boveia, Antonio; Boyd, James; Boyko, Igor; Bozhko, Nikolay; Bozovic-Jelisavcic, Ivanka; Bracinik, Juraj; Braem, André; Branchini, Paolo; Brandenburg, George; Brandt, Andrew; Brandt, Gerhard; Brandt, Oleg; Bratzler, Uwe; Brau, Benjamin; Brau, James; Braun, Helmut; Brelier, Bertrand; Bremer, Johan; Brenner, Richard; Bressler, Shikma; Breton, Dominique; Britton, Dave; Brochu, Frederic; Brock, Ian; Brock, Raymond; Brodbeck, Timothy; Brodet, Eyal; Broggi, Francesco; Bromberg, Carl; Brooijmans, Gustaaf; Brooks, William; Brown, Gareth; Brown, Heather; Brubaker, Erik; Bruckman de Renstrom, Pawel; Bruncko, Dusan; Bruneliere, Renaud; Brunet, Sylvie; Bruni, Alessia; Bruni, Graziano; Bruschi, Marco; Buanes, Trygve; Bucci, Francesca; Buchanan, James; Buchanan, Norman; Buchholz, Peter; Buckingham, Ryan; Buckley, Andrew; Buda, Stelian Ioan; Budagov, Ioulian; Budick, Burton; Büscher, Volker; Bugge, Lars; Buira-Clark, Daniel; Bulekov, Oleg; Bunse, Moritz; Buran, Torleiv; Burckhart, Helfried; Burdin, Sergey; Burgess, Thomas; Burke, Stephen; Busato, Emmanuel; Bussey, Peter; Buszello, Claus-Peter; Butin, François; Butler, Bart; Butler, John; Buttar, Craig; Butterworth, Jonathan; Buttinger, William; Byatt, Tom; Cabrera Urbán, Susana; Caforio, Davide; Cakir, Orhan; Calafiura, Paolo; Calderini, Giovanni; Calfayan, Philippe; Calkins, Robert; Caloba, Luiz; Caloi, Rita; Calvet, David; Calvet, Samuel; Camacho Toro, Reina; Camard, Arnaud; Camarri, Paolo; Cambiaghi, Mario; Cameron, David; Cammin, Jochen; Campana, Simone; Campanelli, Mario; Canale, Vincenzo; Canelli, Florencia; Canepa, Anadi; Cantero, Josu; Capasso, Luciano; Capeans Garrido, Maria Del Mar; Caprini, Irinel; Caprini, Mihai; Capriotti, Daniele; Capua, Marcella; Caputo, Regina; Caramarcu, Costin; Cardarelli, Roberto; Carli, Tancredi; Carlino, Gianpaolo; Carminati, Leonardo; Caron, Bryan; Caron, Sascha; Carrillo Montoya, German D; Carter, Antony; Carter, Janet; Carvalho, João; Casadei, Diego; Casado, Maria Pilar; Cascella, Michele; Caso, Carlo; Castaneda Hernandez, Alfredo Martin; Castaneda-Miranda, Elizabeth; Castillo Gimenez, Victoria; Castro, Nuno Filipe; Cataldi, Gabriella; Cataneo, Fernando; Catinaccio, Andrea; Catmore, James; Cattai, Ariella; Cattani, Giordano; Caughron, Seth; Cauz, Diego; Cavalleri, Pietro; Cavalli, Donatella; Cavalli-Sforza, Matteo; Cavasinni, Vincenzo; Cazzato, Antonio; Ceradini, Filippo; Santiago Cerqueira, Augusto; Cerri, Alessandro; Cerrito, Lucio; Cerutti, Fabio; Cetin, Serkant Ali; Cevenini, Francesco; Chafaq, Aziz; Chakraborty, Dhiman; Chan, Kevin; Chapleau, Bertrand; Chapman, John Derek; Chapman, John Wehrley; Chareyre, Eve; Charlton, Dave; Chavda, Vikash; Cheatham, Susan; Chekanov, Sergei; Chekulaev, Sergey; Chelkov, Gueorgui; Chelstowska, Magda Anna; Chen, Chunhui; Chen, Hucheng; Chen, Li; Chen, Shenjian; Chen, Tingyang; Chen, Xin; Cheng, Shaochen; Cheplakov, Alexander; Chepurnov, Vladimir; Cherkaoui El Moursli, Rajaa; Chernyatin, Valeriy; Cheu, Elliott; Cheung, Sing-Leung; Chevalier, Laurent; Chiefari, Giovanni; Chikovani, Leila; Childers, John Taylor; Chilingarov, Alexandre; Chiodini, Gabriele; Chislett, Rebecca Thalatta; Chizhov, Mihail; Choudalakis, Georgios; Chouridou, Sofia; Christidi, Illectra-Athanasia; Christov, Asen; Chromek-Burckhart, Doris; Chu, Ming-Lee; Chudoba, Jiri; Ciapetti, Guido; Ciba, Krzysztof; Ciftci, Abbas Kenan; Ciftci, Rena; Cinca, Diane; Cindro, Vladimir; Ciobotaru, Matei Dan; Ciocca, Claudia; Ciocio, Alessandra; Cirilli, Manuela; Ciubancan, Mihai; Clark, Allan G; Clark, Philip; Cleland, Bill; Clemens, Jean-Claude; Clement, Benoit; Clement, Christophe; Clifft, Roger; Coadou, Yann; Cobal, Marina; Coccaro, Andrea; Cochran, James H; Coe, Paul; Cogan, Joshua Godfrey; Coggeshall, James; Cogneras, Eric; Cojocaru, Claudiu; Colas, Jacques; Colijn, Auke-Pieter; Collard, Caroline; Collins, Neil; Collins-Tooth, Christopher; Collot, Johann; Colon, German; Conde Muiño, Patricia; Coniavitis, Elias; Conidi, Maria Chiara; Consonni, Michele; Consorti, Valerio; Constantinescu, Serban; Conta, Claudio; Conventi, Francesco; Cook, James; Cooke, Mark; Cooper, Ben; Cooper-Sarkar, Amanda; Cooper-Smith, Neil; Copic, Katherine; Cornelissen, Thijs; Corradi, Massimo; Corriveau, Francois; Cortes-Gonzalez, Arely; Cortiana, Giorgio; Costa, Giuseppe; Costa, María José; Costanzo, Davide; Costin, Tudor; Côté, David; Coura Torres, Rodrigo; Courneyea, Lorraine; Cowan, Glen; Cowden, Christopher; Cox, Brian; Cranmer, Kyle; Crescioli, Francesco; Cristinziani, Markus; Crosetti, Giovanni; Crupi, Roberto; Crépé-Renaudin, Sabine; Cuciuc, Constantin-Mihai; Cuenca Almenar, Cristóbal; Cuhadar Donszelmann, Tulay; Cuneo, Stefano; Curatolo, Maria; Curtis, Chris; Cwetanski, Peter; Czirr, Hendrik; Czyczula, Zofia; D'Auria, Saverio; D'Onofrio, Monica; D'Orazio, Alessia; Da Rocha Gesualdi Mello, Aline; Da Silva, Paulo Vitor; Da Via, Cinzia; Dabrowski, Wladyslaw; Dahlhoff, Andrea; Dai, Tiesheng; Dallapiccola, Carlo; Dam, Mogens; Dameri, Mauro; Damiani, Daniel; Danielsson, Hans Olof; Dannheim, Dominik; Dao, Valerio; Darbo, Giovanni; Darlea, Georgiana Lavinia; Daum, Cornelis; Dauvergne, Jean-Pierre; Davey, Will; Davidek, Tomas; Davidson, Nadia; Davidson, Ruth; Davies, Eleanor; Davies, Merlin; Davison, Adam; Davygora, Yuriy; Dawe, Edmund; Dawson, Ian; Dawson, John; Daya, Rozmin; De, Kaushik; de Asmundis, Riccardo; De Castro, Stefano; De Castro Faria Salgado, Pedro; De Cecco, Sandro; de Graat, Julien; De Groot, Nicolo; de Jong, Paul; De La Taille, Christophe; De la Torre, Hector; De Lotto, Barbara; De Mora, Lee; De Nooij, Lucie; De Oliveira Branco, Miguel; De Pedis, Daniele; de Saintignon, Paul; De Salvo, Alessandro; De Sanctis, Umberto; De Santo, Antonella; De Vivie De Regie, Jean-Baptiste; Dean, Simon; Dedovich, Dmitri; Degenhardt, James; Dehchar, Mohamed; Deile, Mario; Del Papa, Carlo; Del Peso, Jose; Del Prete, Tarcisio; Dell'Acqua, Andrea; Dell'Asta, Lidia; Della Pietra, Massimo; della Volpe, Domenico; Delmastro, Marco; Delpierre, Pierre; Delruelle, Nicolas; Delsart, Pierre-Antoine; Deluca, Carolina; Demers, Sarah; Demichev, Mikhail; Demirkoz, Bilge; Deng, Jianrong; Denisov, Sergey; Derendarz, Dominik; Derkaoui, Jamal Eddine; Derue, Frederic; Dervan, Paul; Desch, Klaus Kurt; Devetak, Erik; Deviveiros, Pier-Olivier; Dewhurst, Alastair; DeWilde, Burton; Dhaliwal, Saminder; Dhullipudi, Ramasudhakar; Di Ciaccio, Anna; Di Ciaccio, Lucia; Di Girolamo, Alessandro; Di Girolamo, Beniamino; Di Luise, Silvestro; Di Mattia, Alessandro; Di Micco, Biagio; Di Nardo, Roberto; Di Simone, Andrea; Di Sipio, Riccardo; Diaz, Marco Aurelio; Diblen, Faruk; Diehl, Edward; Dieli, Michele Vincenzo; Dietl, Hans; Dietrich, Janet; Dietzsch, Thorsten; Diglio, Sara; Dindar Yagci, Kamile; Dingfelder, Jochen; Dionisi, Carlo; Dita, Petre; Dita, Sanda; Dittus, Fridolin; Djama, Fares; Djilkibaev, Rashid; Djobava, Tamar; Barros do Vale, Maria Aline; Do Valle Wemans, André; Doan, Thi Kieu Oanh; Dobbs, Matt; Dobinson, Robert; Dobos, Daniel; Dobson, Ellie; Dobson, Marc; Dodd, Jeremy; Dogan, Ozgen Berkol; Doglioni, Caterina; Doherty, Tom; Doi, Yoshikuni; Dolejsi, Jiri; Dolenc, Irena; Dolezal, Zdenek; Dolgoshein, Boris; Dohmae, Takeshi; Donadelli, Marisilvia; Donega, Mauro; Donini, Julien; Dopke, Jens; Doria, Alessandra; Dos Anjos, Andre; Dosil, Mireia; Dotti, Andrea; Dova, Maria-Teresa; Dowell, John; Doxiadis, Alexander; Doyle, Tony; Drasal, Zbynek; Drees, Jürgen; Dressnandt, Nandor; Drevermann, Hans; Driouichi, Chafik; Dris, Manolis; Dubbert, Jörg; Dubbs, Tim; Dube, Sourabh; Duchovni, Ehud; Duckeck, Guenter; Dudarev, Alexey; Dudziak, Fanny; Dührssen, Michael; Duerdoth, Ian; Duflot, Laurent; Dufour, Marc-Andre; Dunford, Monica; Duran Yildiz, Hatice; Duxfield, Robert; Dwuznik, Michal; Dydak, Friedrich; Dzahini, Daniel; Düren, Michael; Ebenstein, William; Ebke, Johannes; Eckert, Simon; Eckweiler, Sebastian; Edmonds, Keith; Edwards, Clive; Edwards, Nicholas Charles; Ehrenfeld, Wolfgang; Ehrich, Thies; Eifert, Till; Eigen, Gerald; Einsweiler, Kevin; Eisenhandler, Eric; Ekelof, Tord; El Kacimi, Mohamed; Ellert, Mattias; Elles, Sabine; Ellinghaus, Frank; Ellis, Katherine; Ellis, Nicolas; Elmsheuser, Johannes; Elsing, Markus; Ely, Robert; Emeliyanov, Dmitry; Engelmann, Roderich; Engl, Albert; Epp, Brigitte; Eppig, Andrew; Erdmann, Johannes; Ereditato, Antonio; Eriksson, Daniel; Ernst, Jesse; Ernst, Michael; Ernwein, Jean; Errede, Deborah; Errede, Steven; Ertel, Eugen; Escalier, Marc; Escobar, Carlos; Espinal Curull, Xavier; Esposito, Bellisario; Etienne, Francois; Etienvre, Anne-Isabelle; Etzion, Erez; Evangelakou, Despoina; Evans, Hal; Fabbri, Laura; Fabre, Caroline; Fakhrutdinov, Rinat; Falciano, Speranza; Falou, Alain; Fang, Yaquan; Fanti, Marcello; Farbin, Amir; Farilla, Addolorata; Farley, Jason; Farooque, Trisha; Farrington, Sinead; Farthouat, Philippe; Fassnacht, Patrick; Fassouliotis, Dimitrios; Fatholahzadeh, Baharak; Favareto, Andrea; Fayard, Louis; Fazio, Salvatore; Febbraro, Renato; Federic, Pavol; Fedin, Oleg; Fedorko, Ivan; Fedorko, Woiciech; Fehling-Kaschek, Mirjam; Feligioni, Lorenzo; Fellmann, Denis; Felzmann, Ulrich; Feng, Cunfeng; Feng, Eric; Fenyuk, Alexander; Ferencei, Jozef; Ferland, Jonathan; Fernando, Waruna; Ferrag, Samir; Ferrando, James; Ferrara, Valentina; Ferrari, Arnaud; Ferrari, Pamela; Ferrari, Roberto; Ferrer, Antonio; Ferrer, Maria Lorenza; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filippas, Anastasios; Filthaut, Frank; Fincke-Keeler, Margret; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Gordon; Fischer, Peter; Fisher, Matthew; Fisher, Steve; Flechl, Martin; Fleck, Ivor; Fleckner, Johanna; Fleischmann, Philipp; Fleischmann, Sebastian; Flick, Tobias; Flores Castillo, Luis; Flowerdew, Michael; Föhlisch, Florian; Fokitis, Manolis; Fonseca Martin, Teresa; Forbush, David Alan; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Foster, Joe; Fournier, Daniel; Foussat, Arnaud; Fowler, Andrew; Fowler, Ken; Fox, Harald; Francavilla, Paolo; Franchino, Silvia; Francis, David; Frank, Tal; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; Fratina, Sasa; French, Sky; Froeschl, Robert; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gadfort, Thomas; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Gallas, Elizabeth; Gallas, Manuel; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Galyaev, Eugene; Gan, KK; Gao, Yongsheng; Gapienko, Vladimir; Gaponenko, Andrei; Garberson, Ford; Garcia-Sciveres, Maurice; García, Carmen; García Navarro, José Enrique; Gardner, Robert; Garelli, Nicoletta; Garitaonandia, Hegoi; Garonne, Vincent; Garvey, John; Gatti, Claudio; Gaudio, Gabriella; Gaumer, Olivier; Gaur, Bakul; Gauthier, Lea; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gayde, Jean-Christophe; Gazis, Evangelos; Ge, Peng; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerlach, Peter; Gershon, Avi; Geweniger, Christoph; Ghazlane, Hamid; Ghez, Philippe; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giakoumopoulou, Victoria; Giangiobbe, Vincent; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Adam; Gibson, Stephen; Gilbert, Laura; Gilchriese, Murdock; Gilewsky, Valentin; Gillberg, Dag; Gillman, Tony; Gingrich, Douglas; Ginzburg, Jonatan; Giokaris, Nikos; Giordano, Raffaele; Giorgi, Francesco Michelangelo; Giovannini, Paola; Giraud, Pierre-Francois; Giugni, Danilo; Giunta, Michele; Giusti, Paolo; Gjelsten, Børge Kile; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glazov, Alexandre; Glitza, Karl-Walter; Glonti, George; Godfrey, Jennifer; Godlewski, Jan; Goebel, Martin; Göpfert, Thomas; Goeringer, Christian; Gössling, Claus; Göttfert, Tobias; Goldfarb, Steven; Goldin, Daniel; Golling, Tobias; Golovnia, Serguei; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; Gonidec, Allain; Gonzalez, Saul; González de la Hoz, Santiago; Gonzalez Silva, Laura; Gonzalez-Sevilla, Sergio; Goodson, Jeremiah Jet; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorfine, Grant; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Gorokhov, Serguei; Goryachev, Vladimir; Gosdzik, Bjoern; Gosselink, Martijn; Gostkin, Mikhail Ivanovitch; Gouanère, Michel; Gough Eschrich, Ivo; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Grabowska-Bold, Iwona; Grabski, Varlen; Grafström, Per; Grah, Christian; Grahn, Karl-Johan; Grancagnolo, Francesco; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Grau, Nathan; Gray, Heather; Gray, Julia Ann; Graziani, Enrico; Grebenyuk, Oleg; Greenfield, Debbie; Greenshaw, Timothy; Greenwood, Zeno Dixon; Gregor, Ingrid-Maria; Grenier, Philippe; Griesmayer, Erich; Griffiths, Justin; Grigalashvili, Nugzar; Grillo, Alexander; Grinstein, Sebastian; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Grognuz, Joel; Groh, Manfred; Gross, Eilam; Grosse-Knetter, Joern; Groth-Jensen, Jacob; Grybel, Kai; Guarino, Victor; Guest, Daniel; Guicheney, Christophe; Guida, Angelo; Guillemin, Thibault; Guindon, Stefan; Guler, Hulya; Gunther, Jaroslav; Guo, Bin; Guo, Jun; Gupta, Ambreesh; Gusakov, Yury; Gushchin, Vladimir; Gutierrez, Andrea; Gutierrez, Phillip; Guttman, Nir; Gutzwiller, Olivier; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haas, Stefan; Haber, Carl; Hackenburg, Robert; Hadavand, Haleh Khani; Hadley, David; Haefner, Petra; Hahn, Ferdinand; Haider, Stefan; Hajduk, Zbigniew; Hakobyan, Hrachya; Haller, Johannes; Hamacher, Klaus; Hamal, Petr; Hamilton, Andrew; Hamilton, Samuel; Han, Hongguang; Han, Liang; Hanagaki, Kazunori; Hance, Michael; Handel, Carsten; Hanke, Paul; Hansen, John Renner; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hansson, Per; Hara, Kazuhiko; Hare, Gabriel; Harenberg, Torsten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Karl; Hartert, Jochen; Hartjes, Fred; Haruyama, Tomiyoshi; Harvey, Alex; Hasegawa, Satoshi; Hasegawa, Yoji; Hassani, Samira; Hatch, Mark; Hauff, Dieter; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawes, Brian; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Donovan; Hayakawa, Takashi; Hayden, Daniel; Hayward, Helen; Haywood, Stephen; Hazen, Eric; He, Mao; Head, Simon; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heine, Kristin; Heinemann, Beate; Heisterkamp, Simon; Helary, Louis; Heldmann, Michael; Heller, Mathieu; Hellman, Sten; Helsens, Clement; Henderson, Robert; Henke, Michael; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Henry-Couannier, Frédéric; Hensel, Carsten; Henß, Tobias; Medina Hernandez, Carlos; Hernández Jiménez, Yesenia; Herrberg, Ruth; Hershenhorn, Alon David; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hessey, Nigel; Hidvegi, Attila; Higón-Rodriguez, Emilio; Hill, Daniel; Hill, John; Hill, Norman; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirsch, Florian; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hohlfeld, Marc; Holder, Martin; Holmes, Alan; Holmgren, Sven-Olof; Holy, Tomas; Holzbauer, Jenny; Homma, Yasuhiro; Hong, Tae Min; Hooft van Huysduynen, Loek; Horazdovsky, Tomas; Horn, Claus; Horner, Stephan; Horton, Katherine; Hostachy, Jean-Yves; Hou, Suen; Houlden, Michael; Hoummada, Abdeslam; Howarth, James; Howell, David; Hristova, Ivana; Hrivnac, Julius; Hruska, Ivan; Hryn'ova, Tetiana; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Huang, Guang Shun; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Hughes-Jones, Richard; Huhtinen, Mika; Hurst, Peter; Hurwitz, Martina; Husemann, Ulrich; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibbotson, Michael; Ibragimov, Iskander; Ichimiya, Ryo; Iconomidou-Fayard, Lydia; Idarraga, John; Idzik, Marek; Iengo, Paolo; Igonkina, Olga; Ikegami, Yoichi; Ikeno, Masahiro; Ilchenko, Yuri; Iliadis, Dimitrios; Imbault, Didier; Imhaeuser, Martin; Imori, Masatoshi; Ince, Tayfun; Inigo-Golfin, Joaquin; Ioannou, Pavlos; Iodice, Mauro; Ionescu, Gelu; Irles Quiles, Adrian; Ishii, Koji; Ishikawa, Akimasa; Ishino, Masaya; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Itoh, Yuki; Ivashin, Anton; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, John; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakubek, Jan; Jana, Dilip; Jankowski, Ernest; Jansen, Eric; Jantsch, Andreas; Janus, Michel; Jarlskog, Göran; Jeanty, Laura; Jelen, Kazimierz; Jen-La Plante, Imai; Jenni, Peter; Jeremie, Andrea; Jež, Pavel; Jézéquel, Stéphane; Jha, Manoj Kumar; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Ge; Jin, Shan; Jinnouchi, Osamu; Joergensen, Morten Dam; Joffe, David; Johansen, Lars; Johansen, Marianne; Johansson, Erik; Johansson, Per; Johnert, Sebastian; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tegid; Jones, Tim; Jonsson, Ove; Joram, Christian; Jorge, Pedro; Joseph, John; Ju, Xiangyang; Juranek, Vojtech; Jussel, Patrick; Kabachenko, Vasily; Kabana, Sonja; Kaci, Mohammed; Kaczmarska, Anna; Kadlecik, Peter; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kaiser, Steffen; Kajomovitz, Enrique; Kalinin, Sergey; Kalinovskaya, Lidia; Kama, Sami; Kanaya, Naoko; Kaneda, Michiru; Kanno, Takayuki; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kaplon, Jan; Kar, Deepak; Karagoz, Muge; Karnevskiy, Mikhail; Karr, Kristo; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasmi, Azzedine; Kass, Richard; Kastanas, Alex; Kataoka, Mayuko; Kataoka, Yousuke; Katsoufis, Elias; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kayl, Manuel; Kazanin, Vassili; Kazarinov, Makhail; Keates, James Robert; Keeler, Richard; Kehoe, Robert; Keil, Markus; Kekelidze, George; Kelly, Marc; Kennedy, John; Kenney, Christopher John; Kenyon, Mike; Kepka, Oldrich; Kerschen, Nicolas; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Ketterer, Christian; Keung, Justin; Khakzad, Mohsen; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Kharchenko, Dmitri; Khodinov, Alexander; Kholodenko, Anatoli; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Nikolai; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hyeon Jin; Kim, Min Suk; Kim, Peter; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; Kirk, Julie; Kirsch, Guillaume; Kirsch, Lawrence; Kiryunin, Andrey; Kisielewska, Danuta; Kittelmann, Thomas; Kiver, Andrey; Kiyamura, Hironori; Kladiva, Eduard; Klaiber-Lodewigs, Jonas; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klemetti, Miika; Klier, Amit; Klimentov, Alexei; Klingenberg, Reiner; Klinkby, Esben; Klioutchnikova, Tatiana; Klok, Peter; Klous, Sander; Kluge, Eike-Erik; Kluge, Thomas; Kluit, Peter; Kluth, Stefan; Kneringer, Emmerich; Knobloch, Juergen; Knoops, Edith; Knue, Andrea; Ko, Byeong Rok; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kocnar, Antonin; Kodys, Peter; Köneke, Karsten; König, Adriaan; Koenig, Sebastian; Köpke, Lutz; Koetsveld, Folkert; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kohn, Fabian; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kokott, Thomas; Kolachev, Guennady; Kolanoski, Hermann; Kolesnikov, Vladimir; Koletsou, Iro; Koll, James; Kollar, Daniel; Kollefrath, Michael; Kolya, Scott; Komar, Aston; Komaragiri, Jyothsna Rani; Komori, Yuto; Kondo, Takahiko; Kono, Takanori; Kononov, Anatoly; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kootz, Andreas; Koperny, Stefan; Kopikov, Sergey; Korcyl, Krzysztof; Kordas, Kostantinos; Koreshev, Victor; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotamäki, Miikka Juhani; Kotov, Sergey; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasel, Olaf; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, James; Kreisel, Arik; Krejci, Frantisek; Kretzschmar, Jan; Krieger, Nina; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumshteyn, Zinovii; Kruth, Andre; Kubota, Takashi; Kuehn, Susanne; Kugel, Andreas; Kuhl, Thorsten; Kuhn, Dietmar; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kummer, Christian; Kuna, Marine; Kundu, Nikhil; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurata, Masakazu; Kurochkin, Yurii; Kus, Vlastimil; Kuykendall, William; Kuze, Masahiro; Kuzhir, Polina; Kvasnicka, Ondrej; Kvita, Jiri; Kwee, Regina; La Rosa, Alessandro; La Rotonda, Laura; Labarga, Luis; Labbe, Julien; Lablak, Said; Lacasta, Carlos; Lacava, Francesco; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Rémi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laisne, Emmanuel; Lamanna, Massimo; Lampen, Caleb; Lampl, Walter; Lancon, Eric; Landgraf, Ulrich; Landon, Murrough; Landsman, Hagar; Lane, Jenna; Lange, Clemens; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Lapin, Vladimir; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Larionov, Anatoly; Larner, Aimee; Lasseur, Christian; Lassnig, Mario; Lau, Wing; Laurelli, Paolo; Lavorato, Antonia; Lavrijsen, Wim; Laycock, Paul; Lazarev, Alexandre; Lazzaro, Alfio; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Maner, Christophe; Le Menedeu, Eve; Lebedev, Alexander; Lebel, Céline; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Michel; Legendre, Marie; Leger, Annie; LeGeyt, Benjamin; Legger, Federica; Leggett, Charles; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Leltchouk, Mikhail; Lendermann, Victor; Leney, Katharine; Lenz, Tatiana; Lenzen, Georg; Lenzi, Bruno; Leonhardt, Kathrin; Leontsinis, Stefanos; Leroy, Claude; Lessard, Jean-Raphael; Lesser, Jonas; Lester, Christopher; Leung Fook Cheong, Annabelle; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Levitski, Mikhail; Lewandowska, Marta; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bo; Li, Haifeng; Li, Shu; Li, Xuefei; Liang, Zhihua; Liang, Zhijun; Liberti, Barbara; Lichard, Peter; Lichtnecker, Markus; Lie, Ki; Liebig, Wolfgang; Lifshitz, Ronen; Lilley, Joseph; Limbach, Christian; Limosani, Antonio; Limper, Maaike; Lin, Simon; Linde, Frank; Linnemann, James; Lipeles, Elliot; Lipinsky, Lukas; Lipniacka, Anna; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Chuanlei; Liu, Dong; Liu, Hao; Liu, Jianbei; Liu, Minghui; Liu, Shengli; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Lockwitz, Sarah; Loddenkoetter, Thomas; Loebinger, Fred; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Loken, James; Lombardo, Vincenzo Paolo; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Losada, Marta; Loscutoff, Peter; Lo Sterzo, Francesco; Losty, Michael; Lou, Xinchou; Lounis, Abdenour; Loureiro, Karina; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lu, Liang; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Ludwig, Andreas; Ludwig, Dörthe; Ludwig, Inga; Ludwig, Jens; Luehring, Frederick; Luijckx, Guy; Lumb, Debra; Luminari, Lamberto; Lund, Esben; Lund-Jensen, Bengt; Lundberg, Björn; Lundberg, Johan; Lundquist, Johan; Lungwitz, Matthias; Lupi, Anna; Lutz, Gerhard; Lynn, David; Lys, Jeremy; Lytken, Else; Ma, Hong; Ma, Lian Liang; Macana Goia, Jorge Andres; Maccarrone, Giovanni; Macchiolo, Anna; Maček, Boštjan; Machado Miguens, Joana; Mackeprang, Rasmus; Madaras, Ronald; Mader, Wolfgang; Maenner, Reinhard; Maeno, Tadashi; Mättig, Peter; Mättig, Stefan; Magalhaes Martins, Paulo Jorge; Magnoni, Luca; Magradze, Erekle; Mahalalel, Yair; Mahboubi, Kambiz; Mahout, Gilles; Maiani, Camilla; Maidantchik, Carmen; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malecki, Pawel; Malecki, Piotr; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mameghani, Raphael; Mamuzic, Judita; Manabe, Atsushi; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Mangeard, Pierre-Simon; Manjavidze, Ioseb; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Manz, Andreas; Mapelli, Alessandro; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchese, Fabrizio; Marchiori, Giovanni; Marcisovsky, Michal; Marin, Alexandru; Marino, Christopher; Marroquim, Fernando; Marshall, Robin; Marshall, Zach; Martens, Kalen; Marti-Garcia, Salvador; Martin, Andrew; Martin, Brian; Martin, Brian Thomas; Martin, Franck Francois; Martin, Jean-Pierre; Martin, Philippe; Martin, Tim; Martin dit Latour, Bertrand; Martinez, Mario; Martinez Outschoorn, Verena; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Maß, Martin; Massa, Ignazio; Massaro, Graziano; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Mathes, Markus; Matricon, Pierre; Matsumoto, Hiroshi; Matsunaga, Hiroyuki; Matsushita, Takashi; Mattravers, Carly; Maugain, Jean-Marie; Maxfield, Stephen; Maximov, Dmitriy; May, Edward; Mayne, Anna; Mazini, Rachid; Mazur, Michael; Mazzanti, Marcello; Mazzoni, Enrico; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; McGlone, Helen; Mchedlidze, Gvantsa; McLaren, Robert Andrew; Mclaughlan, Tom; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Mechtel, Markus; Medinnis, Mike; Meera-Lebbai, Razzak; Meguro, Tatsuma; Mehdiyev, Rashid; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meinhardt, Jens; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Mendoza Navas, Luis; Meng, Zhaoxia; Mengarelli, Alberto; Menke, Sven; Menot, Claude; Meoni, Evelin; Mercurio, Kevin Michael; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meuser, Stefan; Meyer, Carsten; Meyer, Jean-Pierre; Meyer, Jochen; Meyer, Joerg; Meyer, Thomas Christian; Meyer, W Thomas; Miao, Jiayuan; Michal, Sebastien; Micu, Liliana; Middleton, Robin; Miele, Paola; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Miller, David; Miller, Robert; Mills, Bill; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Miñano, Mercedes; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Miralles Verge, Lluis; Misiejuk, Andrzej; Mitrevski, Jovan; Mitrofanov, Gennady; Mitsou, Vasiliki A; Mitsui, Shingo; Miyagawa, Paul; Miyazaki, Kazuki; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Mockett, Paul; Moed, Shulamit; Moeller, Victoria; Mönig, Klaus; Möser, Nicolas; Mohapatra, Soumya; Mohn, Bjarte; Mohr, Wolfgang; Mohrdieck-Möck, Susanne; Moisseev, Artemy; Moles-Valls, Regina; Molina-Perez, Jorge; Monk, James; Monnier, Emmanuel; Montesano, Simone; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moorhead, Gareth; Mora Herrera, Clemencia; Moraes, Arthur; Morais, Antonio; Morange, Nicolas; Morel, Julien; Morello, Gianfranco; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morii, Masahiro; Morin, Jerome; Morita, Youhei; Morley, Anthony Keith; Mornacchi, Giuseppe; Morone, Maria-Christina; Morozov, Sergey; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Mudrinic, Mihajlo; Mueller, Felix; Mueller, James; Mueller, Klemens; Müller, Thomas; Muenstermann, Daniel; Muijs, Sandra; Muir, Alex; Munwes, Yonathan; Murakami, Koichi; Murray, Bill; Mussche, Ido; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nadal, Jordi; Nagai, Koichi; Nagano, Kunihiro; Nagasaka, Yasushi; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakano, Itsuo; Nanava, Gizo; Napier, Austin; Nash, Michael; Nation, Nigel; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Neal, Homer; Nebot, Eduardo; Nechaeva, Polina; Negri, Andrea; Negri, Guido; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Silke; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Nesterov, Stanislav; Neubauer, Mark; Neusiedl, Andrea; Neves, Ricardo; Nevski, Pavel; Newman, Paul; Nguyen Thi Hong, Van; Nickerson, Richard; Nicolaidou, Rosy; Nicolas, Ludovic; Nicquevert, Bertrand; Niedercorn, Francois; Nielsen, Jason; Niinikoski, Tapio; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolaev, Kirill; Nikolic-Audit, Irena; Nikolopoulos, Konstantinos; Nilsen, Henrik; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nishiyama, Tomonori; Nisius, Richard; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Nomoto, Hiroshi; Nordberg, Markus; Nordkvist, Bjoern; Norton, Peter; Novakova, Jana; Nozaki, Mitsuaki; Nožička, Miroslav; Nozka, Libor; Nugent, Ian Michael; Nuncio-Quiroz, Adriana-Elizabeth; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; Nyman, Tommi; O'Brien, Brendan Joseph; O'Neale, Steve; O'Neil, Dugan; O'Shea, Val; Oakham, Gerald; Oberlack, Horst; Ocariz, Jose; Ochi, Atsuhiko; Oda, Susumu; Odaka, Shigeru; Odier, Jerome; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohshima, Takayoshi; Ohshita, Hidetoshi; Ohska, Tokio Kenneth; Ohsugi, Takashi; Okada, Shogo; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olcese, Marco; Olchevski, Alexander; Oliveira, Miguel Alfonso; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olivito, Dominick; Olszewski, Andrzej; Olszowska, Jolanta; Omachi, Chihiro; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlov, Iliya; Oropeza Barrera, Cristina; Orr, Robert; Ortega, Eduardo; Osculati, Bianca; Ospanov, Rustem; Osuna, Carlos; Otero y Garzon, Gustavo; Ottersbach, John; Ouchrif, Mohamed; Ould-Saada, Farid; Ouraou, Ahmimed; Ouyang, Qun; Owen, Mark; Owen, Simon; Øye, Ola; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Paganis, Efstathios; Paige, Frank; Pajchel, Katarina; Palestini, Sandro; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panes, Boris; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Panuskova, Monika; Paolone, Vittorio; Papadelis, Aras; Papadopoulou, Theodora; Paramonov, Alexander; Park, Woochun; Parker, Andy; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pasqualucci, Enrico; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pecsy, Martin; Pedraza Morales, Maria Isabel; Peleganchuk, Sergey; Peng, Haiping; Pengo, Ruggero; Penson, Alexander; Penwell, John; Perantoni, Marcelo; Perez, Kerstin; Perez Cavalcanti, Tiago; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Peric, Ivan; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Perrodo, Pascal; Persembe, Seda; Peshekhonov, Vladimir; Peters, Onne; Petersen, Brian; Petersen, Jorgen; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Petschull, Dennis; Petteni, Michele; Pezoa, Raquel; Phan, Anna; Phillips, Alan; Phillips, Peter William; Piacquadio, Giacinto; Piccaro, Elisa; Piccinini, Maurizio; Pickford, Andrew; Piec, Sebastian Marcin; Piegaia, Ricardo; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Ping, Jialun; Pinto, Belmiro; Pirotte, Olivier; Pizio, Caterina; Placakyte, Ringaile; Plamondon, Mathieu; Plano, Will; Pleier, Marc-Andre; Pleskach, Anatoly; Poblaguev, Andrei; Poddar, Sahill; Podlyski, Fabrice; Poggioli, Luc; Poghosyan, Tatevik; Pohl, Martin; Polci, Francesco; Polesello, Giacomo; Policicchio, Antonio; Polini, Alessandro; Poll, James; Polychronakos, Venetios; Pomarede, Daniel Marc; Pomeroy, Daniel; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Porter, Robert; Posch, Christoph; Pospelov, Guennady; Pospisil, Stanislav; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Prabhu, Robindra; Pralavorio, Pascal; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Pretzl, Klaus Peter; Pribyl, Lukas; Price, Darren; Price, Lawrence; Price, Michael John; Prichard, Paul; Prieur, Damien; Primavera, Margherita; Prokofiev, Kirill; Prokoshin, Fedor; Protopopescu, Serban; Proudfoot, James; Prudent, Xavier; Przysiezniak, Helenka; Psoroulas, Serena; Ptacek, Elizabeth; Purdham, John; Purohit, Milind; Puzo, Patrick; Pylypchenko, Yuriy; Qian, Jianming; Qian, Zuxuan; Qin, Zhonghua; Quadt, Arnulf; Quarrie, David; Quayle, William; Quinonez, Fernando; Raas, Marcel; Radescu, Voica; Radics, Balint; Rador, Tonguc; Ragusa, Francesco; Rahal, Ghita; Rahimi, Amir; Rahm, David; Rajagopalan, Srinivasan; Rammensee, Michael; Rammes, Marcus; Ramstedt, Magnus; Randrianarivony, Koloina; Ratoff, Peter; Rauscher, Felix; Rauter, Emanuel; Raymond, Michel; Read, Alexander Lincoln; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Reichold, Armin; Reinherz-Aronis, Erez; Reinsch, Andreas; Reisinger, Ingo; Reljic, Dusan; Rembser, Christoph; Ren, Zhongliang; Renaud, Adrien; Renkel, Peter; Rensch, Bertram; Rescigno, Marco; Resconi, Silvia; Resende, Bernardo; Reznicek, Pavel; Rezvani, Reyhaneh; Richards, Alexander; Richter, Robert; Richter-Was, Elzbieta; Ridel, Melissa; Rieke, Stefan; Rijpstra, Manouk; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Rios, Ryan Randy; Riu, Imma; Rivoltella, Giancesare; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robinson, Mary; Robson, Aidan; Rocha de Lima, Jose Guilherme; Roda, Chiara; Roda Dos Santos, Denis; Rodier, Stephane; Rodriguez, Diego; Rodriguez Garcia, Yohany; Roe, Adam; Roe, Shaun; Røhne, Ole; Rojo, Victoria; Rolli, Simona; Romaniouk, Anatoli; Romanov, Victor; Romeo, Gaston; Romero Maltrana, Diego; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Matthew; Rosenbaum, Gabriel; Rosenberg, Eli; Rosendahl, Peter Lundgaard; Rosselet, Laurent; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rossi, Lucio; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexander; Rozen, Yoram; Ruan, Xifeng; Rubinskiy, Igor; Ruckert, Benjamin; Ruckstuhl, Nicole; Rud, Viacheslav; Rudolph, Gerald; Rühr, Frederik; Ruggieri, Federico; Ruiz-Martinez, Aranzazu; Rulikowska-Zarebska, Elzbieta; Rumiantsev, Viktor; Rumyantsev, Leonid; Runge, Kay; Runolfsson, Ogmundur; Rurikova, Zuzana; Rusakovich, Nikolai; Rust, Dave; Rutherfoord, John; Ruwiedel, Christoph; Ruzicka, Pavel; Ryabov, Yury; Ryadovikov, Vasily; Ryan, Patrick; Rybar, Martin; Rybkin, Grigori; Ryder, Nick; Rzaeva, Sevda; Saavedra, Aldo; Sadeh, Iftach; Sadrozinski, Hartmut; Sadykov, Renat; Safai Tehrani, Francesco; Sakamoto, Hiroshi; Salamanna, Giuseppe; Salamon, Andrea; Saleem, Muhammad; Salihagic, Denis; Salnikov, Andrei; Salt, José; Salvachua Ferrando, Belén; Salvatore, Daniela; Salvatore, Pasquale Fabrizio; Salvucci, Antonio; Salzburger, Andreas; Sampsonidis, Dimitrios; Samset, Björn Hallvard; Sandaker, Heidi; Sander, Heinz Georg; Sanders, Michiel; Sandhoff, Marisa; Sandoval, Tanya; Sandstroem, Rikard; Sandvoss, Stephan; Sankey, Dave; Sansoni, Andrea; Santamarina Rios, Cibran; Santoni, Claudio; Santonico, Rinaldo; Santos, Helena; Saraiva, João; Sarangi, Tapas; Sarkisyan-Grinbaum, Edward; Sarri, Francesca; Sartisohn, Georg; Sasaki, Osamu; Sasaki, Takashi; Sasao, Noboru; Satsounkevitch, Igor; Sauvage, Gilles; Sauvan, Jean-Baptiste; Savard, Pierre; Savinov, Vladimir; Savu, Dan Octavian; Savva, Panagiota; Sawyer, Lee; Saxon, David; Says, Louis-Pierre; Sbarra, Carla; Sbrizzi, Antonio; Scallon, Olivia; Scannicchio, Diana; Scarcella, Mark; Schaarschmidt, Jana; Schacht, Peter; Schäfer, Uli; Schaepe, Steffen; Schaetzel, Sebastian; Schaffer, Arthur; Schaile, Dorothee; Schamberger, R. Dean; Schamov, Andrey; Scharf, Veit; Schegelsky, Valery; Scheirich, Daniel; Schernau, Michael; Scherzer, Max; Schiavi, Carlo; Schieck, Jochen; Schioppa, Marco; Schlenker, Stefan; Schlereth, James; Schmidt, Evelyn; Schmidt, Michael; Schmieden, Kristof; Schmitt, Christian; Schmitt, Sebastian; Schmitz, Martin; Schöning, André; Schott, Matthias; Schouten, Doug; Schovancova, Jaroslava; Schram, Malachi; Schroeder, Christian; Schroer, Nicolai; Schuh, Silvia; Schuler, Georges; Schultes, Joachim; Schultz-Coulon, Hans-Christian; Schulz, Holger; Schumacher, Jan; Schumacher, Markus; Schumm, Bruce; Schune, Philippe; Schwanenberger, Christian; Schwartzman, Ariel; Schwemling, Philippe; Schwienhorst, Reinhard; Schwierz, Rainer; Schwindling, Jerome; Scott, Bill; Searcy, Jacob; Sedykh, Evgeny; Segura, Ester; Seidel, Sally; Seiden, Abraham; Seifert, Frank; Seixas, José; Sekhniaidze, Givi; Seliverstov, Dmitry; Sellden, Bjoern; Sellers, Graham; Seman, Michal; Semprini-Cesari, Nicola; Serfon, Cedric; Serin, Laurent; Seuster, Rolf; Severini, Horst; Sevior, Martin; Sfyrla, Anna; Shabalina, Elizaveta; Shamim, Mansoora; Shan, Lianyou; Shank, James; Shao, Qi Tao; Shapiro, Marjorie; Shatalov, Pavel; Shaver, Leif; Shaw, Christian; Shaw, Kate; Sherman, Daniel; Sherwood, Peter; Shibata, Akira; Shichi, Hideharu; Shimizu, Shima; Shimojima, Makoto; Shin, Taeksu; Shmeleva, Alevtina; Shochet, Mel; Short, Daniel; Shupe, Michael; Sicho, Petr; Sidoti, Antonio; Siebel, Anca-Mirela; Siegert, Frank; Siegrist, James; Sijacki, Djordje; Silbert, Ohad; Silva, José; Silver, Yiftah; Silverstein, Daniel; Silverstein, Samuel; Simak, Vladislav; Simard, Olivier; Simic, Ljiljana; Simion, Stefan; Simmons, Brinick; Simonyan, Margar; Sinervo, Pekka; Sinev, Nikolai; Sipica, Valentin; Siragusa, Giovanni; Sisakyan, Alexei; Sivoklokov, Serguei; Sjölin, Jörgen; Sjursen, Therese; Skinnari, Louise Anastasia; Skovpen, Kirill; Skubic, Patrick; Skvorodnev, Nikolai; Slater, Mark; Slavicek, Tomas; Sliwa, Krzysztof; Sloan, Terrence; Sloper, John erik; Smakhtin, Vladimir; Smirnov, Sergei; Smirnova, Lidia; Smirnova, Oxana; Smith, Ben Campbell; Smith, Douglas; Smith, Kenway; Smizanska, Maria; Smolek, Karel; Snesarev, Andrei; Snow, Steve; Snow, Joel; Snuverink, Jochem; Snyder, Scott; Soares, Mara; Sobie, Randall; Sodomka, Jaromir; Soffer, Abner; Solans, Carlos; Solar, Michael; Solc, Jaroslav; Soldatov, Evgeny; Soldevila, Urmila; Solfaroli Camillocci, Elena; Solodkov, Alexander; Solovyanov, Oleg; Sondericker, John; Soni, Nitesh; Sopko, Vit; Sopko, Bruno; Sorbi, Massimo; Sosebee, Mark; Soukharev, Andrey; Spagnolo, Stefania; Spanò, Francesco; Spighi, Roberto; Spigo, Giancarlo; Spila, Federico; Spiriti, Eleuterio; Spiwoks, Ralf; Spousta, Martin; Spreitzer, Teresa; Spurlock, Barry; St Denis, Richard Dante; Stahl, Thorsten; Stahlman, Jonathan; Stamen, Rainer; Stanecka, Ewa; Stanek, Robert; Stanescu, Cristian; Stapnes, Steinar; Starchenko, Evgeny; Stark, Jan; Staroba, Pavel; Starovoitov, Pavel; Staude, Arnold; Stavina, Pavel; Stavropoulos, Georgios; Steele, Genevieve; Steinbach, Peter; Steinberg, Peter; Stekl, Ivan; Stelzer, Bernd; Stelzer, Harald Joerg; Stelzer-Chilton, Oliver; Stenzel, Hasko; Stevenson, Kyle; Stewart, Graeme; Stillings, Jan Andre; Stockmanns, Tobias; Stockton, Mark; Stoerig, Kathrin; Stoicea, Gabriel; Stonjek, Stefan; Strachota, Pavel; Stradling, Alden; Straessner, Arno; Strandberg, Jonas; Strandberg, Sara; Strandlie, Are; Strang, Michael; Strauss, Emanuel; Strauss, Michael; Strizenec, Pavol; Ströhmer, Raimund; Strom, David; Strong, John; Stroynowski, Ryszard; Strube, Jan; Stugu, Bjarne; Stumer, Iuliu; Stupak, John; Sturm, Philipp; Soh, Dart-yin; Su, Dong; Subramania, Halasya Siva; Succurro, Antonella; Sugaya, Yorihito; Sugimoto, Takuya; Suhr, Chad; Suita, Koichi; Suk, Michal; Sulin, Vladimir; Sultansoy, Saleh; Sumida, Toshi; Sun, Xiaohu; Sundermann, Jan Erik; Suruliz, Kerim; Sushkov, Serge; Susinno, Giancarlo; Sutton, Mark; Suzuki, Yu; Svatos, Michal; Sviridov, Yuri; Swedish, Stephen; Sykora, Ivan; Sykora, Tomas; Szeless, Balazs; Sánchez, Javier; Ta, Duc; Tackmann, Kerstin; Taffard, Anyes; Tafirout, Reda; Taga, Adrian; Taiblum, Nimrod; Takahashi, Yuta; Takai, Helio; Takashima, Ryuichi; Takeda, Hiroshi; Takeshita, Tohru; Talby, Mossadek; Talyshev, Alexey; Tamsett, Matthew; Tanaka, Junichi; Tanaka, Reisaburo; Tanaka, Satoshi; Tanaka, Shuji; Tanaka, Yoshito; Tani, Kazutoshi; Tannoury, Nancy; Tappern, Geoffrey; Tapprogge, Stefan; Tardif, Dominique; Tarem, Shlomit; Tarrade, Fabien; Tartarelli, Giuseppe Francesco; Tas, Petr; Tasevsky, Marek; Tassi, Enrico; Tatarkhanov, Mous; Tayalati, Yahya; Taylor, Christopher; Taylor, Frank; Taylor, Geoffrey; Taylor, Wendy; Teixeira Dias Castanheira, Matilde; Teixeira-Dias, Pedro; Temming, Kim Katrin; Ten Kate, Herman; Teng, Ping-Kun; Terada, Susumu; Terashi, Koji; Terron, Juan; Terwort, Mark; Testa, Marianna; Teuscher, Richard; Thadome, Jocelyn; Therhaag, Jan; Theveneaux-Pelzer, Timothée; Thioye, Moustapha; Thoma, Sascha; Thomas, Juergen; Thompson, Emily; Thompson, Paul; Thompson, Peter; Thompson, Stan; Thomson, Evelyn; Thomson, Mark; Thun, Rudolf; Tic, Tomáš; Tikhomirov, Vladimir; Tikhonov, Yury; Timmermans, Charles; Tipton, Paul; Tique Aires Viegas, Florbela De Jes; Tisserant, Sylvain; Tobias, Jürgen; Toczek, Barbara; Todorov, Theodore; Todorova-Nova, Sharka; Toggerson, Brokk; Tojo, Junji; Tokár, Stanislav; Tokunaga, Kaoru; Tokushuku, Katsuo; Tollefson, Kirsten; Tomoto, Makoto; Tompkins, Lauren; Toms, Konstantin; Tong, Guoliang; Tonoyan, Arshak; Topfel, Cyril; Topilin, Nikolai; Torchiani, Ingo; Torrence, Eric; Torró Pastor, Emma; Toth, Jozsef; Touchard, Francois; Tovey, Daniel; Traynor, Daniel; Trefzger, Thomas; Treis, Johannes; Tremblet, Louis; Tricoli, Alesandro; Trigger, Isabel Marian; Trincaz-Duvoid, Sophie; Trinh, Thi Nguyet; Tripiana, Martin; Trischuk, William; Trivedi, Arjun; Trocmé, Benjamin; Troncon, Clara; Trottier-McDonald, Michel; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiakiris, Menelaos; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsung, Jieh-Wen; Tsuno, Soshi; Tsybychev, Dmitri; Tua, Alan; Tuggle, Joseph; Turala, Michal; Turecek, Daniel; Turk Cakir, Ilkay; Turlay, Emmanuel; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Tyrvainen, Harri; Tzanakos, George; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ugland, Maren; Uhlenbrock, Mathias; Uhrmacher, Michael; Ukegawa, Fumihiko; Unal, Guillaume; Underwood, David; Undrus, Alexander; Unel, Gokhan; Unno, Yoshinobu; Urbaniec, Dustin; Urkovsky, Evgeny; Urrejola, Pedro; Usai, Giulio; Uslenghi, Massimiliano; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Vahsen, Sven; Valenta, Jan; Valente, Paolo; Valentinetti, Sara; Valkar, Stefan; Valladolid Gallego, Eva; Vallecorsa, Sofia; Valls Ferrer, Juan Antonio; van der Graaf, Harry; van der Kraaij, Erik; Van Der Leeuw, Robin; van der Poel, Egge; van der Ster, Daniel; Van Eijk, Bob; van Eldik, Niels; van Gemmeren, Peter; van Kesteren, Zdenko; van Vulpen, Ivo; Vandelli, Wainer; Vandoni, Giovanna; Vaniachine, Alexandre; Vankov, Peter; Vannucci, Francois; Varela Rodriguez, Fernando; Vari, Riccardo; Varnes, Erich; Varouchas, Dimitris; Vartapetian, Armen; Varvell, Kevin; Vassilakopoulos, Vassilios; Vazeille, Francois; Vegni, Guido; Veillet, Jean-Jacques; Vellidis, Constantine; Veloso, Filipe; Veness, Raymond; Veneziano, Stefano; Ventura, Andrea; Ventura, Daniel; Venturi, Manuela; Venturi, Nicola; Vercesi, Valerio; Verducci, Monica; Verkerke, Wouter; Vermeulen, Jos; Vest, Anja; Vetterli, Michel; Vichou, Irene; Vickey, Trevor; Viehhauser, Georg; Viel, Simon; Villa, Mauro; Villaplana Perez, Miguel; Vilucchi, Elisabetta; Vincter, Manuella; Vinek, Elisabeth; Vinogradov, Vladimir; Virchaux, Marc; Viret, Sébastien; Virzi, Joseph; Vitale, Antonio; Vitells, Ofer; Viti, Michele; Vivarelli, Iacopo; Vives Vaque, Francesc; Vlachos, Sotirios; Vlasak, Michal; Vlasov, Nikolai; Vogel, Adrian; Vokac, Petr; Volpi, Guido; Volpi, Matteo; Volpini, Giovanni; von der Schmitt, Hans; von Loeben, Joerg; von Radziewski, Holger; von Toerne, Eckhard; Vorobel, Vit; Vorobiev, Alexander; Vorwerk, Volker; Vos, Marcel; Voss, Rudiger; Voss, Thorsten Tobias; Vossebeld, Joost; Vranjes, Nenad; Vranjes Milosavljevic, Marija; Vrba, Vaclav; Vreeswijk, Marcel; Vu Anh, Tuan; Vuillermet, Raphael; Vukotic, Ilija; Wagner, Wolfgang; Wagner, Peter; Wahlen, Helmut; Wakabayashi, Jun; Walbersloh, Jorg; Walch, Shannon; Walder, James; Walker, Rodney; Walkowiak, Wolfgang; Wall, Richard; Waller, Peter; Wang, Chiho; Wang, Haichen; Wang, Hulin; Wang, Jike; Wang, Jin; Wang, Joshua C; Wang, Rui; Wang, Song-Ming; Warburton, Andreas; Ward, Patricia; Warsinsky, Markus; Watkins, Peter; Watson, Alan; Watson, Miriam; Watts, Gordon; Watts, Stephen; Waugh, Anthony; Waugh, Ben; Weber, Jens; Weber, Marc; Weber, Michele; Weber, Pavel; Weidberg, Anthony; Weigell, Philipp; Weingarten, Jens; Weiser, Christian; Wellenstein, Hermann; Wells, Phillippa; Wen, Mei; Wenaus, Torre; Wendler, Shanti; Weng, Zhili; Wengler, Thorsten; Wenig, Siegfried; Wermes, Norbert; Werner, Matthias; Werner, Per; Werth, Michael; Wessels, Martin; Weydert, Carole; Whalen, Kathleen; Wheeler-Ellis, Sarah Jane; Whitaker, Scott; White, Andrew; White, Martin; White, Sebastian; Whitehead, Samuel Robert; Whiteson, Daniel; Whittington, Denver; Wicek, Francois; Wicke, Daniel; Wickens, Fred; Wiedenmann, Werner; Wielers, Monika; Wienemann, Peter; Wiglesworth, Craig; Wiik, Liv Antje Mari; Wijeratne, Peter Alexander; Wildauer, Andreas; Wildt, Martin Andre; Wilhelm, Ivan; Wilkens, Henric George; Will, Jonas Zacharias; Williams, Eric; Williams, Hugh; Willis, William; Willocq, Stephane; Wilson, John; Wilson, Michael Galante; Wilson, Alan; Wingerter-Seez, Isabelle; Winkelmann, Stefan; Winklmeier, Frank; Wittgen, Matthias; Wolter, Marcin Wladyslaw; Wolters, Helmut; Wooden, Gemma; Wosiek, Barbara; Wotschack, Jorg; Woudstra, Martin; Wraight, Kenneth; Wright, Catherine; Wrona, Bozydar; Wu, Sau Lan; Wu, Xin; Wu, Yusheng; Wulf, Evan; Wunstorf, Renate; Wynne, Benjamin; Xaplanteris, Leonidas; Xella, Stefania; Xie, Song; Xie, Yigang; Xu, Chao; Xu, Da; Xu, Guofa; Yabsley, Bruce; Yamada, Miho; Yamamoto, Akira; Yamamoto, Kyoko; Yamamoto, Shimpei; Yamamura, Taiki; Yamaoka, Jared; Yamazaki, Takayuki; Yamazaki, Yuji; Yan, Zhen; Yang, Haijun; Yang, Un-Ki; Yang, Yi; Yang, Yi; Yang, Zhaoyu; Yanush, Serguei; Yao, Weiming; Yao, Yushu; Yasu, Yoshiji; Ybeles Smit, Gabriel Valentijn; Ye, Jingbo; Ye, Shuwei; Yilmaz, Metin; Yoosoofmiya, Reza; Yorita, Kohei; Yoshida, Riktura; Young, Charles; Youssef, Saul; Yu, Dantong; Yu, Jaehoon; Yu, Jie; Yuan, Li; Yurkewicz, Adam; Zaets, Vassilli; Zaidan, Remi; Zaitsev, Alexander; Zajacova, Zuzana; Zalite, Youris; Zanello, Lucia; Zarzhitsky, Pavel; Zaytsev, Alexander; Zeitnitz, Christian; Zeller, Michael; Zemla, Andrzej; Zendler, Carolin; Zenin, Anton; Zenin, Oleg; Ženiš, Tibor; Zenonos, Zenonas; Zenz, Seth; Zerwas, Dirk; Zevi della Porta, Giovanni; Zhan, Zhichao; Zhang, Dongliang; Zhang, Huaqiao; Zhang, Jinlong; Zhang, Xueyao; Zhang, Zhiqing; Zhao, Long; Zhao, Tianchi; Zhao, Zhengguo; Zhemchugov, Alexey; Zheng, Shuchen; Zhong, Jiahang; Zhou, Bing; Zhou, Ning; Zhou, Yue; Zhu, Cheng Guang; Zhu, Hongbo; Zhu, Yingchun; Zhuang, Xuai; Zhuravlov, Vadym; Zieminska, Daria; Zimmermann, Robert; Zimmermann, Simone; Zimmermann, Stephanie; Ziolkowski, Michael; Zitoun, Robert; Živković, Lidija; Zmouchko, Viatcheslav; Zobernig, Georg; Zoccoli, Antonio; Zolnierowski, Yves; Zsenei, Andras; zur Nedden, Martin; Zutshi, Vishnu; Zwalinski, Lukasz

2012-01-03

Proton-proton collisions at $\\sqrt{s}=7$ TeV and heavy ion collisions at $\\sqrt{s_{NN}}$=2.76 TeV were produced by the LHC and recorded using the ATLAS experiment's trigger system in 2010. The LHC is designed with a maximum bunch crossing rate of 40 MHz and the ATLAS trigger system is designed to record approximately 200 of these per second. The trigger system selects events by rapidly identifying signatures of muon, electron, photon, tau lepton, jet, and B meson candidates, as well as using global event signatures, such as missing transverse energy. An overview of the ATLAS trigger system, the evolution of the system during 2010 and the performance of the trigger system components and selections based on the 2010 collision data are shown. A brief outline of plans for the trigger system in 2011 is presented

The CMS calorimeter trigger upgrade for the LHC Run II

CERN Document Server

Zabi, Alexandre

2014-01-01

The CMS experiment implements a sophisticated two-level online selection system that achieves a rejection factor of nearly 10e5. The first level (L1) is based on coarse information coming from the calorimeters and the muon detectors while the High-Level Trigger combines fine-grain information from all sub-detectors. During Run II, the LHC will increase its centre of mass energy up to 13 TeV and progressively reach an instantaneous luminosity of 2e34 cm-2s-1. In order to guarantee a successful and ambitious physics program under this intense environment, the CMS Trigger and Data acquisition system must be consolidated. In particular the L1 calorimeter Trigger hardware and architecture will be modified. The goal is to maintain the current thresholds (e.g., for electrons and photons) and improve the performance for the selection of tau leptons. This can only be achieved by designing an updated trigger architecture based on the recent microTCA technology. Racks can be equipped with fast optical links and latest...

Searching for Heavy Photons with Detached Verices in the Heavy Photon Search Experiment

Energy Technology Data Exchange (ETDEWEB)

Szumila-Vance, Holly [Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2017-08-01

The Jefferson Lab Heavy Photon Search (HPS) experiment is searching for a hypothetical massive particle called the heavy photon which could mediate a dark electromagnetic-type force. If heavy photons kinetically mix with Standard Model photons, they may be radiated by electrons scattering from a heavy nucleus and then decay to e+e- pairs. HPS uniquely searches for heavy photons that either decay at the target or a measurable distance after. The experiment utilizes a silicon vertex tracker (SVT) for momentum and vertex reconstruction, together with an electromagnetic calorimeter for measuring particle energies and triggering events. The HPS experiment took its first data during the spring 2015 engineering run using a 1 GeV electron beam incident on a tungsten target and its second data in the spring of 2016 at a beam energy of 2.3 GeV. The 2015 run obtained two days of production data that was used for the first physics results. The analysis of the data was conducted as a blinded analysis by tuning cuts on 10% of the data. This dissertation discusses the displaced vertex search for heavy photons in the 2015 engineering run. It describes the theoretical motivation for looking for heavy photons and provides an overview of the HPS experimental design and performance. The performance details of the experiment are primarily derived from the 2015 engineering run with some discussion from the higher energy running in 2016. This dissertation further discusses the cuts used to optimize the displaced vertex search and the results of the search. The displaced vertex search did not set a limit on the heavy photon but did validate the methodology for conducting the search. Finally, we used the full data set to make projections and guide future analyses.

Thermal photon production in Au + Au collisions: Viscous corrections in two different hydrodynamic formalisms

Energy Technology Data Exchange (ETDEWEB)

Peralta-Ramos, J., E-mail: jperalta@ift.unesp.b [Instituto de Fisica Teorica, Universidade Estadual Paulista, Rua Doutor Bento Teobaldo Ferraz 271, Bloco II, 01140-070 Sao Paulo (Brazil); Nakwacki, M.S., E-mail: sole@iafe.uba.a [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-090 Sao Paulo (Brazil)

2011-02-01

We calculate the spectra of produced thermal photons in Au + Au collisions taking into account the nonequilibrium contribution to photon production due to finite shear viscosity. The evolution of the fireball is modeled by second-order as well as by divergence-type 2+1 dissipative hydrodynamics, both with an ideal equation of state and with one based on Lattice QCD that includes an analytical crossover. The spectrum calculated in the divergence-type theory is considerably enhanced with respect to the one calculated in the second-order theory, the difference being entirely due to differences in the viscous corrections to photon production. Our results show that the differences in hydrodynamic formalisms are an important source of uncertainty in the extraction of the value of {eta}/s from measured photon spectra. The uncertainty in the value of {eta}/s associated with different hydrodynamic models used to compute thermal photon spectra is larger than the one occurring in matching hadron elliptic flow to RHIC data.

Simultaneous morphological and functional imaging of the honeybee's brain by two-photon microscopy

International Nuclear Information System (INIS)

Haase, A.

2011-01-01

Thanks to its rather simply structured but highly performing brain, the honeybee (Apis mellifera) is an important model for neurobiological studies. Therefore there is a great need for new functional imaging modalities adapted to this species. Herein we give a detailed report on the development and performance of a platform for in vivo functional and morphological imaging of the honeybee's brain, focusing on its primary olfactory centres, the antennal lobes (ALs). The experimental setup consists of a two-photon microscope combined with a synchronized odour stimulus generator. Our imaging platform allows to simultaneously obtain both morphological measurements of the ALs functional units, the glomeruli, and in vivo calcium recording of their neural activity. We were able to record the characteristic glomerular response maps to odour stimuli applied to the bee's antennae. Our approach offers several advantages over the commonly used conventional fluorescence microscopy. Two-photon microscopy provides substantial enhancement in both spatial and temporal resolutions, while minimizing photo damage. Calcium recordings show a more than fourfold improvement in the functional signal with respect to the techniques available up to now. Finally, the extended penetration depth, thanks to the infrared excitation, allows the functional imaging of profound glomeruli which have not been optically accessible up to now.

Time gated fluorescence lifetime imaging and micro-volume spectroscopy using two-photon excitation

NARCIS (Netherlands)

Sytsma, J.; Vroom, J.M.; de Grauw, C.J.; Gerritsen, H.C.

A scanning microscope utilizing two-photon excitation in combination with fluorescence lifetime contrast is presented. The microscope makes use of a tunable femtosecond titanium:sapphire laser enabling the two-photon excitation of a broad range of fluorescent molecules, including UV probes.

Two-Photon Activation of p-Hydroxyphenacyl Phototriggers: Toward Spatially Controlled Release of Diethyl Phosphate and ATP.

Science.gov (United States)

Houk, Amanda L; Givens, Richard S; Elles, Christopher G

2016-03-31

Two-photon activation of the p-hydroxyphenacyl (pHP) photoactivated protecting group is demonstrated for the first time using visible light at 550 nm from a pulsed laser. Broadband two-photon absorption measurements reveal a strong two-photon transition (>10 GM) near 4.5 eV that closely resembles the lowest-energy band at the same total excitation energy in the one-photon absorption spectrum of the pHP chromophore. The polarization dependence of the two-photon absorption band is consistent with excitation to the same S3 ((1)ππ*) excited state for both one- and two-photon activation. Monitoring the progress of the uncaging reaction under nonresonant excitation at 550 nm confirms a quadratic intensity dependence and that two-photon activation of the uncaging reaction is possible using visible light in the range 500-620 nm. Deprotonation of the pHP chromophore under mildly basic conditions shifts the absorption band to lower energy (3.8 eV) in both the one- and two-photon absorption spectra, suggesting that two-photon activation of the pHP chromophore may be possible using light in the range 550-720 nm. The results of these measurements open the possibility of spatially and temporally selective release of biologically active compounds from the pHP protecting group using visible light from a pulsed laser.

Two-way QKD with single-photon-added coherent states

Science.gov (United States)

Miranda, Mario; Mundarain, Douglas

2017-12-01

In this work we present a two-way quantum key distribution (QKD) scheme that uses single-photon-added coherent states and displacement operations. The first party randomly sends coherent states (CS) or single-photon-added coherent states (SPACS) to the second party. The latter sends back the same state it received. Both parties decide which kind of states they are receiving by detecting or not a photon on the received signal after displacement operations. The first party must determine whether its sent and received states are equal; otherwise, the case must be discarded. We are going to show that an eavesdropper provided with a beam splitter gets the same information in any of the non-discarded cases. The key can be obtained by assigning 0 to CS and 1 to SPACS in the non-discarded cases. This protocol guarantees keys' security in the presence of a beam splitter attack even for states with a high number of photons in the sent signal. It also works in a lossy quantum channel, becoming a good bet for improving long-distance QKD.

Near-IR Two-Photon Fluorescent Sensor for K(+) Imaging in Live Cells.

Science.gov (United States)

Sui, Binglin; Yue, Xiling; Kim, Bosung; Belfield, Kevin D

2015-08-19

A new two-photon excited fluorescent K(+) sensor is reported. The sensor comprises three moieties, a highly selective K(+) chelator as the K(+) recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (>52-fold) in detecting K(+) over other physiological metal cations. Upon binding K(+), the sensor switches from nonfluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K(+) sensing in living cells.