Nuclear Spin Dynamics of Ionized Phosphorus Donors in Silicon

We demonstrate the coherent control and electrical readout of the nuclear spins of ionized phosphorus donors in natural silicon. By combining pulsed illumination with coherent electron spin manipulation, we selectively ionize the donor depending on its nuclear spin state, exploiting a spin-dependent recombination process via a spin pair at the Si/SiO2 interface. The nuclear-spin coherence time of the ionized donor is 18 ms, two orders of magnitude longer than in the neutral donor state, rendering the ionized donor a potential resource as a quantum memory. The presented experimental techniques allow for spectroscopy of ionized-donor nuclear spins, increase the sensitivity of electrically detected electron nuclear double resonance by more than two orders of magnitude, and give experimental access to the lifetime of parallel electron spin pairs.Comment: 6 pages, 4 figure

Une application iPad pour l’annotation collaborative des manuscrits médiévaux avec le protocole SharedCanvas : «Formes à toucher»

Formes à toucher est une application pour iPAD développée sous la direction de l’Institut de recherche et d’histoire des textes et la Bibliothèque nationale de France et publiée sous licence GNU-GPL. Conçue en collaboration avec des ergonomes, elle démontre que la technologie n’o re pas simplement une amélioration du confort de l’usager mais modi e profondément les méthodes de travail et les questionnements de la recherche en SHS. Malgré l’accès ubiquitaire aux ressources numérisées, le rapport à l’image reste surtout un rapport d’illustration et non d’exploitation assistée par ordinateur, alors que l’analyse d’images et la prise en compte des formes est au cœur des enjeux actuels en SHS. Les études d’usage montrent que l’application est utilisable aussi bien dans un contexte de recherche (annotations personnelles ou d’équipe) que pédagogique (paléographie, histoire de l’art). L’utilisation du modèle de données SharedCanvas, fondé sur RDF, permet d’assurer l’interopérabilité avec d’autres bibliothèques numériques et de futures applications similaires dans le domaine du Linked Open Data

Theoretical study of hydrogen microstructure in models of hydrogenated amorphous silicon

We study the distribution of hydrogen and various hydride configurations in realistic models of a-Si:H for two different concentration generated via experimentally constrained molecular relaxation approach (ECMR) [1]. The microstructure corresponding to low ( 20%) concentration of H atoms are addressed and are compared to the experimental results with particular emphasis on the size of H clusters and local environment of H atoms.The linewidths of the nuclear magnetic resonance (NMR) spectrum for the model configurations are calculated in order to compare to the experimental NMR data. Our study shows the presence of isolated hydrogen atoms, small and relatively large clusters with average proton-proton neighbor distance in the clusters around 1.6 to 2.4 Angstrom that have been observed in multiple quantum NMR experiments.Comment: 5 pages, 5 figure

Electrical Detection of Coherent Nuclear Spin Oscillations in Phosphorus-Doped Silicon Using Pulsed ENDOR

We demonstrate the electrical detection of pulsed X-band Electron Nuclear Double Resonance (ENDOR) in phosphorus-doped silicon at 5\,K. A pulse sequence analogous to Davies ENDOR in conventional electron spin resonance is used to measure the nuclear spin transition frequencies of the $^{31}$P nuclear spins, where the $^{31}$P electron spins are detected electrically via spin-dependent transitions through Si/SiO$_2$ interface states, thus not relying on a polarization of the electron spin system. In addition, the electrical detection of coherent nuclear spin oscillations is shown, demonstrating the feasibility to electrically read out the spin states of possible nuclear spin qubits.Comment: 5 pages, 3 figure

Measuring Group Velocity in Seismic Noise Correlation Studies Based on Phase Coherence and Resampling Strategies

Seismic noise cross correlation studies are of increasing importance in the seismological research community due to the ubiquity of noise sources and advances on how to use the seismic noise wave field for structural imaging and monitoring purposes. Stacks of noise cross correlations are now routinely used to extract empirical Green's functions between station pairs. In regional and global scale studies, mostly surface waves are extracted due to their dominance in seismic noise wave fields. Group arrival times measured from the time-frequency representation of frequency dispersive surface waves are further used in tomographic inversions to image seismic structure. Often, the group arrivals are not clearly identified or ambiguous depending on the signal and noise characteristics. Here, we present a procedure to robustly measure group velocities using the time-frequency domain phase-weighted stack (PWS) combined with data resampling and decision strategies. The time-frequency PWS improves signal extraction through incoherent signal attenuation during the stack of the noise cross correlations. Resampling strategies help to identify signals robust against data variations and to assess their errors. We have gathered these ingredients in an algorithm where the decision strategies and tuning parameters are reduced for semiautomated processing schemes. Our numerical and field data examples show a robust assignment of surface-wave group arrivals. The method is computational efficient thanks to an implementation based on pseudoanalytic frames of wavelets and enables processing large amounts of data.This work was supported in part by the Project MISTERIOS under Grant CGL2013-48601-C2-1-R, in part by the MIMOSA under Grant ANR-14-CE01-0012, in part by the COST Action ES1401 TIDES, in part by AGAUR, and in part by the FP7 Marie Curie Project through SV's Beatriu de Pinos Fellowship under Contract 600385. This is IPGP contribution 3814.Peer reviewe

Electrical detection of spin echoes for phosphorus donors in silicon

The electrical detection of spin echoes via echo tomography is used to observe decoherence processes associated with the electrical readout of the spin state of phosphorus donor electrons in silicon near a SiO$_2$ interface. Using the Carr-Purcell pulse sequence, an echo decay with a time constant of $1.7\pm0.2 \rm{\mu s}$ is observed, in good agreement with theoretical modeling of the interaction between donors and paramagnetic interface states. Electrical spin echo tomography thus can be used to study the spin dynamics in realistic spin qubit devices for quantum information processing.Comment: 14 pages, 3 figure

Specifying a TEI-XML Based Format for Aligning Text to Image at Character Level

International audienceThis papers presents an experience of specifying and implementing an XML format for text to image alignment at word and character level within the TEI framework. The format in question is a supplementary markup layer applied to heterogeneous transcriptions of medieval Latin and French manuscripts encoded using different " flavors " of the TEI (normalized for critical editions, diplomatic or palaeographic transcriptions). One of the problems that had to be solved was identifying " non-alignable " spans in various kinds of transcriptions. Originally designed in the framework of a research project on the ontology of letter-forms in medieval Latin and vernacular (mostly French) manuscripts and inscriptions, this format can be of use for all kinds of projects that involve fine-grain alignment of transcriptions with zones on digital images