On the indistinguishability of Raman photons

We provide a theoretical framework to study the effect of dephasing on the quantum indistinguishability of single photons emitted from a coherently driven cavity QED $\Lambda$-system. We show that with a large excited-state detuning, the photon indistinguishability can be drastically improved provided that the fluctuation rate of the noise source affecting the excited state is fast compared with the photon emission rate. In some cases a spectral filter is required to realize this improvement, but the cost in efficiency can be made small.Comment: 18 pages, 3 figures, final versio

PENGEMBANGAN PROGRAM INTERVENSI DINI BERSUMBERDAYA KELUARGA PADA ANAK CEREBRAL PALSY DENGAN HAMBATAN KOMUNIKASI

Penelitian ini dilatarbelakangi oleh kurangnya pemahaman, penerimaan, dan sikap orang tua terhadap hambatan yang dihadapi anak. Hal ini berdampak pada kemampuan keluarga dalam memberikan layanan intervensi dini di rumah. Tujuan dari penelitian ini adalah untuk merumuskan program intervensi dini bersumber daya keluarga yang akan menjadi pedoman orang tua dalam melaksanakan intervensi. Penelitian ini menggunakan pendekatan kualitatif dengan metode deskriptif. Subjek dalam penelitian ini adalah satu keluarga yang memiliki anak Cerebral Palsy dengan hambatan komunikasi di Ciamis. Teknik pengumpulan data yang digunakan adalah observasi, wawancara, dan studi dokumentasi. Hasil penelitian menunjukkan bahwa: 1) anak memiliki hambatan komunikasi yang pencapaian perkembangan komunikasi verbalnya setara dengan anak usia 2-3 tahun dan usia kalender saat ini 5 tahun. 2) rendahnya tingkat pemahaman orangtua terhadap hambatan anak. 3). Rumusan program intervensi dini bersumber daya keluarga ini berdasarkan kondisi objektif serta kebutuhan keluarga dan anak. 4). tingkat pemahaman orang tua mengenai hambatan anak meningkat serta terjadi perubahan sikap dan perilaku orang tua kepada anak;--- The study was motivated by the lack of understanding, acceptance as well as the attitude of the parents toward their child’s obstacles. It somehow has an impact on family’s capacity to give early intervention support at home. This study was aimed at formulating an early intervention program to the child. The study used descriptive qualitative method involving a single family having a child suffering from Cerebral Palsy causing communication barrier at Ciamis. The techniques used in collecting the data were observations, interviews, and document analysis. The study revealed several findings as follows: 1) the child had communication barrier which made her communication verbal developmental stage was equal to 2-3 years old children. 2) The lack of understanding, acceptance and attitude of the parents toward their child’s communication barrier as well as the support in delivering early intervention at home. 3) The early intervention family-based program’s formulation was based on the objective condition as well as the needs’ of both the child and the parents. 4) The level understanding parents of the barriers to child increase and a change in attitudes and behavior of parents to child

Photoluminescence of single colour defects in 50 nm diamond nanocrystals

We used optical confocal microscopy to study optical properties of diamond 50 nm nanocrystals first irradiated with an electron beam, then dispersed as a colloidal solution and finally deposited on a silica slide. At room temperature, under CW laser excitation at a wavelength of 514.5 nm we observed perfectly photostable single Nitrogen-Vacancy (NV) colour defects embedded in the nanocrystals. From the zero-phonon line around 575 nm in the spectrum of emitted light, we infer a neutral NV0 type of defect. Such nanoparticle with intrinsic fluorescence are highly promising for applications in biology where long-term emitting fluorescent bio-compatible nanoprobes are still missing.Comment: proceedings of ICDS 23 conference (23rd International Conference on Defects in Semiconductors, July 24 - July 29, 2005, Awaji Island, Hyogo, Japan); to appear in "Physica B

Coherent Population Trapping of Single Spins in Diamond Under Optical Excitation

Coherent population trapping is demonstrated in single nitrogen-vacancy centers in diamond under optical excitation. For sufficient excitation power, the fluorescence intensity drops almost to the background level when the laser modulation frequency matches the 2.88 GHz splitting of the ground states. The results are well described theoretically by a four-level model, allowing the relative transition strengths to be determined for individual centers. The results show that all-optical control of single spins is possible in diamond.Comment: minor correction

Coupling Single NV Centers in Diamond to Optical Microcavities

Coupling of the NV^- ZPL to a silica microcavity and tapered fiber is demonstrated at cryogenic temperatures. Coupling to a high-Q cavity should enhance the usefulness of the NV^-for quantum information applications

Polarization-Correlated Photon Pairs from a Single Quantum Dot

Polarization correlation in a linear basis, but not entanglement, is observed between the biexciton and single-exciton photons emitted by a single InAs quantum dot in a two-photon cascade. The results are well described quantitatively by a probabilistic model that includes two decay paths for a biexciton through a non-degenerate pair of one-exciton states, with the polarization of the emitted photons depending on the decay path. The results show that spin non-degeneracy due to quantum-dot asymmetry is a significant obstacle to the realization of an entangled-photon generation device.Comment: 4 pages, 4 figures, revised discussio

Quality and Safety Aspects of Infant Nutrition

Quality and safety aspects of infant nutrition are of key importance for child health, but oftentimes they do not get much attention by health care professionals whose interest tends to focus on functional benefits of early nutrition. Unbalanced diets and harmful food components induce particularly high risks for untoward effects in infants because of their rapid growth, high nutrient needs, and their typical dependence on only one or few foods during the first months of life. The concepts, standards and practices that relate to infant food quality and safety were discussed at a scientific workshop organized by the Child Health Foundation and the Early Nutrition Academy jointly with the European Society for Paediatric Gastroenterology, Hepatology and Nutrition, and a summary is provided here. The participants reviewed past and current issues on quality and safety, the role of different stakeholders, and recommendations to avert future issues. It was concluded that a high level of quality and safety is currently achieved, but this is no reason for complacency. The food industry carries the primary responsibility for the safety and suitability of their products, including the quality of composition, raw materials and production processes. Introduction of new or modified products should be preceded by a thorough science based review of suitability and safety by an independent authority. Food safety events should be managed on an international basis. Global collaboration of food producers, food-safety authorities, paediatricians and scientists is needed to efficiently exchange information and to best protect public health. Copyright (C) 2012 S. Karger AG, Base

Entanglement on mixed stabilizer states: normal forms and reduction procedures

Published versio

Properties of a single photon generated by a solid-state emitter: effects of pure dephasing

We investigate the properties of a single photon generated by a solid-state emitter subject to strong pure dephasing. We employ a model in which all the elements of the system, including the propagating fields, are treated quantum mechanically. We analytically derive the density matrix of the emitted photon, which contains full information about the photon, such as its pulse profile, power spectrum, and purity. We visualize these analytical results using realistic parameters and reveal the conditions for maximizing the purity of generated photons.Comment: 25pages(one column), 10 figure

Sub-microsecond correlations in photoluminescence from InAs quantum dots

Photon correlation measurements reveal memory effects in the optical emission of single InAs quantum dots with timescales from 10 to 800 ns. With above-band optical excitation, a long-timescale negative correlation (antibunching) is observed, while with quasi-resonant excitation, a positive correlation (blinking) is observed. A simple model based on long-lived charged states is presented that approximately explains the observed behavior, providing insight into the excitation process. Such memory effects can limit the internal efficiency of light emitters based on single quantum dots, and could also be problematic for proposed quantum-computation schemes.Comment: 8 pages, 8 figure