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Single Photon (single + photon)
Terms modified by Single Photon Selected AbstractsThe effects of degeneracy of atomic levels on single-photon emission via Raman scatteringLASER PHYSICS LETTERS, Issue 8 2008V.A. Reshetov Abstract The three-level , -type atom with degenerate atomic levels is considered, one of its transitions being driven by the coherent field, the other being coupled to the single-mode quantized field of the high-Q cavity. The probability of emission of a single photon in the cavity via Raman scattering versus the mutual orientation of polarization vectors of the cavity mode and of the driving coherent pulse is studied. The efficiency of the retrieval of a single-photon excitation, stored in the atomic ground state (as suggested, e.g., in paper [1]), versus the mutual orientation of polarizations of cavity modes and of the coherent "write" and "read" pulses is also investigated. The numerical calculations are carried out for the transitions between hyperfine components of the ground 6S1/2 and excited 6P3/2 states of Cesium atoms, which were exploited in the experiments [1]. The optimal polarizations providing the maximum probability of photon emission and maximum retrieval efficiency are determined. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Double-blind, randomized, placebo-controlled study to evaluate the effects of tegaserod on gastric motor, sensory and myoelectric function in healthy volunteersALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2006N. J. TALLEY Summary Background The effects of tegaserod on gastric accommodation and postprandial satiety remain unclear. Aim To compare the effects of tegaserod 6 mg twice daily vs. placebo on gastric volumes, postprandial symptoms, gastric emptying, small bowel transit and the surface electrogastrogram in female and male healthy volunteers. Methods Randomized, double-blind, placebo-controlled study evaluated gastric function before and after 7 days of tegaserod 6 mg twice daily (n = 21) vs. placebo (n = 20) in healthy volunteers. Validated methods were used to study gastric emptying, myoelectrical activity, volumes and satiation postnutrient challenge. Results There were no significant effects of tegaserod on the primary endpoints assessing gastric function: emptying of solids or liquids, total gastric volumes or myoelectrical activity. Maximum tolerated volume and aggregate symptom score with nutrient challenge on placebo were 1035 mL (±44) and 130 (±15) vs. 989 mL (±43) and 117 (±15) during tegaserod, respectively (all P = N.S.). Postprandial change in proximal gastric volume by single photon emission-computed tomography was decreased in females on tegaserod (246 ± 30) vs. placebo (358 ± 32) (P = 0.015). Proximal fasting volumes in females were increased on tegaserod (126 ± 12) vs. placebo (92 ± 13) (P = 0.066). Conclusions While tegaserod decreased proximal gastric volume change after a meal, it does not appear to have significant effects on gastric motor and sensory function in healthy individuals. Further studies are required in patients with disturbances of gastric motor and sensory function. [source] Exercise- or dipyridamole-loaded QGS is useful to evaluate myocardial ischemia and viability in the patients with a history of Kawasaki diseasePEDIATRICS INTERNATIONAL, Issue 5 2005Yuichi Ishikawa AbstractBackground:,Evaluation of myocardial ischemia and viability is very important for the management of patients with a history of Kawasaki disease (KD). 99mTc-tetrofosmin myocardial perfusion scintigraphy combined with quantitative gated single photon computed emission tomography (QGS) gives us information, not only about perfusion, but also the percentage change in left ventricular wall thickness (%WT) and relative changes in left ventricular wall motion (LVM). Methods:,The subjects were 27 patients with a history of KD followed as outpatients at the National Cardiovascular Center, Osaka, Japan. Exercise-loaded QGS was performed on 21 patients, and dipyridamole- loaded QGS was performed in six patients younger than 7 years old. Results:,Perfusion defects (PD) were observed in 12 patients. Of the 12 patients, four with old myocardial infarction (OMI) had decreased %WT. All patients with OMI showed a decrease in %WT in the areas where PD was seen on the image. The other eight patients without OMI showed no decrease in %WT. In non-infarcted cases, the %WT was normal in the PD-positive area. Conclusions:,It is possible to evaluate myocardial ischemia and viability in KD patients by comparing PD on the image with %WT determined by QGS using exercise or drug-loaded myocardial scintigraphy alone. [source] Solar cell as a heat engine: energy,entropy analysis of photovoltaic conversionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2008Tom MarkvartArticle first published online: 13 NOV 200 Abstract A thermodynamic theory for the voltage or free energy generated by a quantum solar energy converter which has recently been proposed, is developed here in a more direct and simpler way. We consider separately the luminescence and conversion of a single photon of the incident radiation. The energy/entropy balance for the conversion process yields an expression for the voltage in a form familiar from the classical thermodynamics of the work carried out by the heat engine. A similar balance for the absorption and emission of light gives an expression for the irreversible entropy generation which reduces the open circuit voltage generated by the solar cell. Detailed expressions for losses due to individual mechanisms, including non-radiative recombination, are obtained with the use of an approximation where photons in the incident and emitted beams are modelled as an ideal two-dimensional gas. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Generation of single photons and correlated photon pairs using InAs quantum dotsFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 11-12 2004C. Santori This article reviews recent work on non-classical light generation using semiconductor quantum dots. Experimental results for single-photon generation are presented, including suppression of the two-photon probability, coherence properties and two-photon interference. An experiment demonstrating generation of polarization-correlated photon pairs from biexciton recombination is also reviewed. [source] CdSe quantum dot in a ZnSe nanowire as an efficient source of single photonsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009A. Tribu Abstract We report on our development of fabrication of CdSe QD in ZnSe nanowire. We have been able to obtain high quality structures with very good optical properties. This has allowed us to measure photon emission from single quantum dots and to demonstrate photon antibunching. We show that this new type of II,VI quantum dot is very promising for high temperature operation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Single-photon and photon-pair emission from CdSe/Zn(S,Se) quantum dotsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003S. Strauf Abstract We report on the generation of triggered single photons and photon pairs relying on pulsed optical excitation of epitaxially grown self-assembled CdSe quantum dots (QDs). Single-photon emission is studied on individual CdSe/Zn(S,Se) QDs for temperatures up to 200 K. At low temperatures nearly perfect single-photon emission is achieved whereas at higher temperatures an increasing multi-photon emission probability due to spectrally overlapping acoustic phonon sidebands of neighboring QDs is observed. The multi-photon emission probability of a bare QD (background subtracted) is strongly suppressed. Furthermore, the polarization cross correlation of the biexciton,exciton cascade has been investigated in a CdSe/ZnSe QD at low temperatures. A strong polarization correlation of the emitted photon pairs of ,74% is observed in a linear detection basis. [source] | |||||||||||||