Field-free two-direction alignment alternation of linear molecules by elliptic laser pulses

We show that a linear molecule subjected to a short specific elliptically polarized laser field yields postpulse revivals exhibiting alignment alternatively located along the orthogonal axis and the major axis of the ellipse. The effect is experimentally demonstrated by measuring the optical Kerr effect along two different axes. The conditions ensuring an optimal field-free alternation of high alignments along both directions are derived.Comment: 5 pages, 4 color figure

What are the effects of the reliability model uncertainties in the maintenance decisions?

Most of the works proposed for the design of reliability test plans  are  devoted  to  the  guaranty  of  the  reliability performance  of  a  product  but  scarce  of  them  tackles maintenance  issues.  On  the  other  hand,  classical maintenance  optimization  criteria  rarely  take  into  account the variability of the failure parameters due to lack of data, especially when the data collection in the operating phase is expensive.  The  objective  of  this  paper  is  to  highlight through a numerical experiment the impact of the test plan design  defined  here  by  the  number  of  the  products  to  be tested and the test duration on the performance of a classical condition-based maintenance (CBM) policy

Femmes et microfinance : espoirs et désillusions de l'expérience indienne

National audienc

Quantum Plasmonics with multi-emitters: Application to adiabatic control

We construct mode-selective effective models describing the interaction of N quantum emitters (QEs) with the localised surface plasmon polaritons (LSPs) supported by a spherical metal nanoparticle (MNP) in an arbitrary geometric arrangement of the QEs. We develop a general formulation in which the field response in the presence of the nanosystem can be decomposed into orthogonal modes with the spherical symmetry as an example. We apply the model in the context of quantum information, investigating on the possibility of using the LSPs as mediators of an efficient control of population transfer between two QEs. We show that a Stimulated Raman Adiabatic Passage configuration allows such a transfer via a decoherence-free dark state when the QEs are located on the same side of the MNP and very closed to it, whereas the transfer is blocked when the emitters are positioned at the opposite sides of the MNP. We explain this blockade by the destructive superposition of all the interacting plasmonic modes

Time Minimal Trajectories for a Spin 1/2 Particle in a Magnetic Field

In this paper we consider the minimum time population transfer problem for the $z$-component of the spin of a (spin 1/2) particle driven by a magnetic field, controlled along the x axis, with bounded amplitude. On the Bloch sphere (i.e. after a suitable Hopf projection), this problem can be attacked with techniques of optimal syntheses on 2-D manifolds. Let $(-E,E)$ be the two energy levels, and $|\Omega(t)|\leq M$ the bound on the field amplitude. For each couple of values $E$ and $M$, we determine the time optimal synthesis starting from the level $-E$ and we provide the explicit expression of the time optimal trajectories steering the state one to the state two, in terms of a parameter that can be computed solving numerically a suitable equation. For $M/E<<1$, every time optimal trajectory is bang-bang and in particular the corresponding control is periodic with frequency of the order of the resonance frequency $\omega_R=2E$. On the other side, for $M/E>1$, the time optimal trajectory steering the state one to the state two is bang-bang with exactly one switching. Fixed $E$ we also prove that for $M\to\infty$ the time needed to reach the state two tends to zero. In the case $M/E>1$ there are time optimal trajectories containing a singular arc. Finally we compare these results with some known results of Khaneja, Brockett and Glaser and with those obtained by controlling the magnetic field both on the $x$ and $y$ directions (or with one external field, but in the rotating wave approximation). As byproduct we prove that the qualitative shape of the time optimal synthesis presents different patterns, that cyclically alternate as $M/E\to0$, giving a partial proof of a conjecture formulated in a previous paper.Comment: 31 pages, 10 figures, typos correcte

A genetic analysis of variable number of tandem repeats (VNTR) polymorphism in the horse

Restriction fragment length polymorphism detected with the 33.6 minisatellite probe (Jeffreys et al, 1985) was analysed in 3 horse families of paternal half-sibs and in a sample of stallions from 4 breeds. Among the bands detected on Hae III genomic DNA digests, it was found that strongly hybridizing fragments behaved as alleles at 2 different loci. These 2 loci, showing 7 and 3 detectable alleles, were not closely linked to each other nor to informative blood groups and protein markers. No neo-mutation in allele length was observed at these 2 loci ip the 3 families. In the stallion sample, 8 alleles were detected at the first locus and no differences were found between their frequencies in the 4 breeds. Heterozygosity and polymorphism information content (PIC) values estimated in the 4 breeds show that the Thoroughbred is the least variable breed and the Arab the most. In the whole population the PIC values were 0.73 and 0.70 respectively.Le polymorphisme de longueur de fragment de restriction détecté par la sonde minisatellite 33.6 (Jeffreys et al, 1985) a été analysé chez le cheval dans trois familles de demi-germains paternels et dans un échantillon d’étalons de quatre races. Parmi toutes les bandes révélées à partir d’ADN génomique digéré par Hae III, les fragments donnant un signal intense se comportent comme des allèles ségrégeant à deux locus différents. Ceux-ci, qui possèdent respectivement sept et trois allèles détectables, ne sont pas étroitement liés entre eux ni avec les locus informatifs des groupes sanguins et des protéines du sang. Aucune néo-mutation de longueur des allèles n’a été détectée dans les trois familles. Dans l’échantillon des étalons, huit allèles ont été observés au premier locus et aucune différence de fréquence n’apparaît entre les quatre races. Les valeurs d’hétérozygotie et les valeurs informatives des polymorphismes (PIC) estimées sur cet échantillon montrent que la race de Pur-sang est la moins variable à l’opposé de la race Arabe. Les valeurs estimées sur la population totale sont respectivement de 0,73 et de 0, 70

Pulse-driven near-resonant quantum adiabatic dynamics: lifting of quasi-degeneracy

We study the quantum dynamics of a two-level system driven by a pulse that starts near-resonant for small amplitudes, yielding nonadiabatic evolution, and induces an adiabatic evolution for larger amplitudes. This problem is analyzed in terms of lifting of degeneracy for rising amplitudes. It is solved exactly for the case of linear and exponential rising. Approximate solutions are given in the case of power law rising. This allows us to determine approximative formulas for the lineshape of resonant excitation by various forms of pulses such as truncated trig-pulses. We also analyze and explain the various superpositions of states that can be obtained by the Half Stark Chirped Rapid Adiabatic Passage (Half-SCRAP) process.Comment: 21 pages, 12 figure