Reply to the Comment on `Deterministic Single-Photon Source for Distributed Quantum Networking'

Reply to the comment of H. J. Kimble [quant-ph/0210032] on the experiment realizing a "deterministic single-photon source for distributed quantum networking" by Kuhn, Hennrich, and Rempe [Phys. Rev. Lett. 89, 067901 (2002), quant-ph/0204147].Comment: 1 page 1 figur

Two-photon contributions to the elastic electron-nucleon scattering in the Skyrme model

Das maßgebliche Ziel dieser Arbeit ist die Berechnung des Anteils der QCD Anomalie an der elastischen Elektron-Proton-Streuung. Auf der Grundlage des Skyrme-Modells werden die Protonen als Solitonlösungen verstanden und quantisiert. Der Beitrag zum Wirkungsquerschnitt entspricht in niedrigster Ordnung der Interferenz des Ein-Photon-Austausches mit dem Zwei-Photon-Austausch. Letzterer weist eine ultraviolette Divergenz auf, die durch die Hinzunahme eines effektiven Counterterms renormiert wird. Der Counterterm trägt zur Breite des Zerfalls des neutralen Pions in ein Elektron-Positron-Paar bei und wird dadurch bestimmt. Die Auswirkung der Anomalie auf die Rosenbluth-Extraktion der elektromagnetischen Formfaktoren und die Diskrepanz zur Messung der Polarisationsobservablen wird ausgiebig diskutiert. Zusätzlich zum Beitrag der Anomalie wird die zu erwartende Korrektur aufgrund der effektiven Zwei-Photon-Kopplung des nicht-linearen-sigma-Modells abgeschätzt.The most important goal of this work is the calculation of the contribution arising from the anomaly of QCD to the inelastic electron-proton scattering. Based on the Skryme model the protons are realized as soliton solutions in effective chiral theories. The next to leading order contribution to the cross section is given by the interference between the one- and two-photon exchange. The latter contains an ultraviolet divergence, which is renormalized by a local effective counterterm. This counterterm contributes to the width of the neutral pion decay which determines the finite part of the counterterm coefficient. The affect of the anomaly to the Rosenbluth separation of the electromagnetic form factors as well as the discrepance regarding the polarization measurements is extensively discussed within the Skyrme model. In addition, the correction as expected from the effective two-photon coupling of the non-linear-sigma model is estimated

Charge Redistribution And Electronic Behaviour Of Gold-coper Alloys: Bulk And Surface Studies

The electronic and physical properties of noble metals and their alloys have been the focus of research for many years. They are considered prototypes for the investigation of full d-band interactions and Friedel charge screening.;We have studied a series of bulk Au-Cu alloys, with varying compositions and ordering, in order to determine the nature and amount of charge transfer between the two components. We also examine the validity of two models; charge compensation and d-d repulsion. To probe the electronic behaviour upon alloying, we employ two techniques, namely photoemission and X-ray absorption. From photoemission, we find unique behaviour in the alloy valence band, indicating separate contribution from each component and distinctive movement showing the validity of the d-d repulsion model. Semi-quantitative results for the amount of d charge transfer (independently determined by X-ray absorption experiments) and conduction charge transfer from Mossbauer isomer shifts, clearly show that Au loses d charge but is overcompensated by a gain of s-p charge giving the Au site a small overall gain of charge in line with electroneutrality and electronegativity arguments. It was found that the amount of charge transfer is directly related to the local configuration of the alloy (number of Cu neighbours around the Au site) and that the valence band behaviour is dependent on the dilution of Au-Au interactions (and also Cu-Cu interactions).;Also of more recent importance, is the study of model bimetallic catalysts, such as Au on Ru(001) and Cu on Ru(001). We have focussed not only on these bimetallic systems but also on a trimetallic system, Au-Cu on Ru(001). Using the results of the bulk study, indicating unique behaviour upon alloying especially in the valence band, we have found that co-deposition of these components, at room temperature and in the monolayer regime, leads to alloy formation which is not observable in the bulk. We propose a mechanism based on the heats of adsorption of the components, the heat of formation of Au-Cu alloys, and the role of the substrate in reducing the activation barrier

Transition from antibunching to bunching in cavity QED

The photon statistics of the light emitted from an atomic ensemble into a single field mode of an optical cavity is investigated as a function of the number of atoms. The light is produced in a Raman transition driven by a pump laser and the cavity vacuum [M.Hennrich et al., Phys. Rev. Lett. 85, 4672 (2000)], and a recycling laser is employed to repeat this process continuously. For weak driving, a smooth transition from antibunching to bunching is found for about one intra-cavity atom. Remarkably, the bunching peak develops within the antibunching dip. For saturated driving and a growing number of atoms, the bunching amplitude decreases and the bunching duration increases, indicating the onset of Raman lasing.Comment: 4 pages, 4 figure

Quantum Beat of Two Single Photons

The interference of two single photons impinging on a beam splitter is measured in a time-resolved manner. Using long photons of different frequencies emitted from an atom-cavity system, a quantum beat with a visibility close to 100% is observed in the correlation between the photodetections at the output ports of the beam splitter. The time dependence of the beat amplitude reflects the coherence properties of the photons. Most remarkably, simultaneous photodetections are never observed, so that a temporal filter allows one to obtain perfect two-photon coalescence even for non-perfect photons.Comment: 4 pages, 3 figure

Ketogenic diets attenuate cyclooxygenase and lipoxygenase gene expression in multiple sclerosis

Background: Adapted ketogenic diet (AKD) and caloric restriction (CR) have been suggested as alternative therapeutic strategies for inflammatory, hyperproliferative and neurodegenerative diseases. Pro-inflammatory eicosanoids have been implicated in the pathogenesis of multiple sclerosis since they augment vascular permeability and induce leukocyte migration into the brain. We explored the impact of ketogenic diets on gene expression of biosynthetic enzymes for pro- (ALOX5, COX1, COX2) and anti-inflammatory (ALOX15) eicosanoids in patients with relapsing-remitting multiple sclerosis. Methods: 60 adults were prospectively recruited for this six months randomized controlled trial and the impact of dietary treatment on the Multiple Sclerosis Quality of Life-54 index (ClinicalTrials.gov (NCT01538355) has previously been published. Here we explored 24 patients (8 controls, 5 on CR and 11 on AKD). For statistical analysis we combined the two diet groups to a single pooled treatment group. Findings: Inter-group comparison indicated that expression of the pro-inflammatory ALOX5 in the pooled treatment group was significantly (p <0.05) reduced when compared with the control group. Moreover, intra-group comparison (same individuals before and after dietary treatment) suggested significantly impaired expression of other pro-inflammatory enzymes, such as COX1 (p < 0.001) and COX2 ( p < 0.05). Finally, pretreatment cross-group analysis revealed a significant positive correlation between expression of pro-inflammatory ALOX5 and COX2 and an inverse correlation of ALOX5 and COX1 expression with the MSQoL-54 index. Interpretation: Ketogenic diets can reduce the expression of enzymes involved in the biosynthesis of pro-inflammatory eicosanoids. Pharmacological interference with eicosanoid biosynthesis might constitute a strategy supplementing current therapeutic approaches for MS. (C) 2018 The Authors. Published by Elsevier B.V