Polarization-labelling Spectroscopy Of Iodine-monochloride: The D-prime (2) And A-prime (2) States

Iodine stands as the best known diatomic halogen molecule. It is now followed by iodine monochloride. One of the three lowest ion-pair states, namely D\u27 ((OMEGA) = 2), is characterized by using the Optical-Optical-Double-Resonance, (UPARR)(UPARR), state-selective polarization-labelling technique. Data were cumulated for vibrational levels v = 0-2 and 15-28, including extensive coverage of two avoided crossings between D\u27 and E states, at v = 0 and 1. The main spectroscopic constants for D\u27 state of I (\u2735)Cl are T(,e) = 39061.830(80), (omega)(,e) = 173.63(35), (omega)(,e)x(,e) = 0.5572(27), 10(\u272)B(,e) = 5.4782(41), 10(\u274)(alpha)(,e) = 2.019(10)cm(\u27-1) and 10r(,e) = 3.350nm. The Rydberg-Klein-Rees (RKR) potential is given for the D\u27(2) ion-pair state of I(\u2735)Cl up to v = 28. The D\u27 state is perturbed by the neighboring (beta) state, their electronic interaction term is evaluated at 1.860(77), 93% of the Van Vleck pure precession value. The three lowest ion-pair states in ICl, D\u27, (beta) and E, have very similar electronic energy, vibrational energy and equilibrium bond distance as it can be expected.;By extending the technique to three steps (OOTR), (UPARR)(UPARR)(DARR), we characterized the first excited state A\u27 ((OMEGA) = 2), above the ground state of ICl. Data from v = 2 to 28 were fitted to a Dunham expansion, and v = 23 to 38 were fitted to a near-dissociation expansion. The main spectroscopic constants for A\u27(2) state of I(\u2735)Cl are T(,e) = 12682.05(27), (omega)(,e) = 224.57(15), (omega)(,e)x(,e) = 1.882(29), 10(\u272)B(,e) = 8.648(48), 10(\u274) (alpha)(,e) = 6.48(23), 10(\u278) D(,e) (TURNEQ) 5.27(20) cm(\u27-1) and 10r(,e) = 2.665nm. The A\u27(2) state shows some similarity with the other ((\u273)(pi)) case (a) signature states, namely A(1) and B(0(\u27+)), their vibrational energy and equilibrium bond distance being very close. No sign of perturbation have been observed in A\u27 state even if data of partial coverage go up to (TURN)70 cm(\u27-1) from the dissociation limit, 17557.57cm(\u27-1), I((\u272)P(,3/2)) + Cl ((\u272)P(,3/2)) to which converge ten electronic states. The Rydberg-Klein-Rees (RKR) potential curve is given for A\u27(2) state of I Cl up to v = 38

Manipulating time-bin qubits with fiber optics components

We propose two experimental schemes to implement arbitrary unitary single qubit operations on single photons encoded in time-bin qubits. Both schemes require fiber optics components that are available with current technology.Comment: 2 pages, 3 figures, to be published in the proceedings of the IEEE LEOS 2006 topical meeting, Quebec city, Canada, July 200

Cardiorespiratory And Peripheral Adaptations After Cardiac Transplantation

The cardiovascular, pulmonary and musculoskeletal systems were investigated in seven studies of patients with end-stage heart failure before and/or after receiving a heart transplant. The purposes of the studies were to determine the time course and magnitude of the changes in peak oxygen uptake, cardiopulmonary response to exercise and peripheral skeletal muscle histology and biochemistry after cardiac transplantation. In addition, the physiological basis for the limited exercise capacity and the effect of exercise posture on cardiac performance and secretion of atrial natriuretic peptide was also evaluated in cardiac transplant patients.;In the first study, the peak oxygen uptake almost doubled from the pre-transplant values in the first three months following transplantation. The increased exercise capacity was associated with improved blood pressure, heart rate and ventilatory responses to exercise. In the second study, lung volumes, but not diffusing capacity, improved in the first year after cardiac transplantation. In the third study, increased skeletal muscle fibre cross sectional area and glycolytic and oxidative enzyme activities were observed in the first year post transplantation using skeletal muscle biopsy of the vastus lateralis.;In the fourth study, the low peak oxygen uptake, as a percent of predicted, in patients after cardiac transplantation appears to be due to some peripheral limitations.;In the fifth study, the marked increase in cardiac filling pressure during supine exercise was associated with a lower slope of the cardiac output-oxygen uptake relationship when compared to the upright position. In the sixth study, higher cardiac filling pressures at peak supine exercise were associated with higher plasma ANP levels when compared to exercise in the upright posture. In the final study, two patients with mitochondrial myopathy who underwent cardiac transplantation demonstrated the typical hyperkinetic circulatory response to exercise despite cardiac denervation.;The present results show that exercise capacity improves markedly early after cardiac transplantation. The improved exercise capacity is associated with changes in lung function and peripheral skeletal muscle adaptations in the first year after transplantation. The exercise capacity however is still low at one or more years following transplantation (2/3 of predicted) possibly due to peripheral limitations

Exploring Macroscopic Entanglement with a Single Photon and Coherent States

Entanglement between macroscopically populated states can easily be created by combining a single photon and a bright coherent state on a beam-splitter. Motivated by the simplicity of this technique, we report on a method using displacement operations in the phase space and basic photon detections to reveal such an entanglement. We demonstrate through preliminary experimental results, that this eminently feasible approach provides an attractive way for exploring entanglement at various scales, ranging from one to a thousand photons. This offers an instructive viewpoint to gain insight into the reasons that make it hard to observe quantum features in our macroscopic world.Comment: 6 pages, 10 figures. v2: Updated version. The corresponding experiment is reported in arXiv:1212.3710. See also arXiv:1306.084

Detector-Device-Independent Quantum Key Distribution

Recently, a quantum key distribution (QKD) scheme based on entanglement swapping, called measurement-device-independent QKD (mdiQKD), was proposed to bypass all detector side-channel attacks. While mdiQKD is conceptually elegant and offers a supreme level of security, the experimental complexity is challenging for practical systems. For instance, it requires interference between two widely separated independent single-photon sources, and the rates are dependent on detecting two photons - one from each source. Here we experimentally demonstrate a QKD scheme that removes the need for a two-photon system and instead uses the idea of a two-qubit single-photon (TQSP) to significantly simplify the implementation and improve the efficiency of mdiQKD in several aspects.Comment: 5 pages + 3 figure

A source of polarization-entangled photon pairs interfacing quantum memories with telecom photons

We present a source of polarization-entangled photon pairs suitable for the implementation of long-distance quantum communication protocols using quantum memories. Photon pairs with wavelengths 883 nm and 1338 nm are produced by coherently pumping two periodically poled nonlinear waveguides embedded in the arms of a polarization interferometer. Subsequent spectral filtering reduces the bandwidth of the photons to 240 MHz. The bandwidth is well-matched to a quantum memory based on an Nd:YSO crystal, to which, in addition, the center frequency of the 883 nm photons is actively stabilized. A theoretical model that includes the effect of the filtering is presented and accurately fits the measured correlation functions of the generated photons. The model can also be used as a way to properly assess the properties of the source. The quality of the entanglement is revealed by a visibility of V = 96.1(9)% in a Bell-type experiment and through the violation of a Bell inequality.Comment: 15 pages, 8 figures, 3 table

Caractérisation des réponses du PMLS au mouvement de deuxième ordre (modulé par le contraste)

La perception visuelle ne se résume pas à la simple perception des variations de la quantité de lumière qui atteint la rétine. L’image naturelle est en effet composée de variation de contraste et de texture que l’on qualifie d’information de deuxième ordre (en opposition à l’information de premier ordre : luminance). Il a été démontré chez plusieurs espèces qu’un mouvement de deuxième ordre (variation spatiotemporelle du contraste ou de la texture) est aisément détecté. Les modèles de détection du mouvement tel le modèle d’énergie d’Adelson et Bergen ne permettent pas d’expliquer ces résultats, car le mouvement de deuxième ordre n’implique aucune variation de la luminance. Il existe trois modèles expliquant la détection du mouvement de deuxième ordre : la présence d’une circuiterie de type filter-rectify-filter, un mécanisme de feature-tracking ou simplement l’existence de non-linéarités précoces dans le traitement visuel. Par ailleurs, il a été proposé que l’information visuelle de deuxième ordre soit traitée par une circuiterie neuronale distincte de celle qui traite du premier ordre. Bon nombre d’études réfutent cependant cette théorie et s’entendent sur le fait qu’il n’y aurait qu’une séparation partielle à bas niveau. Les études électrophysiologiques sur la perception du mouvement de deuxième ordre ont principalement été effectuées chez le singe et le chat. Chez le chat, toutefois, seules les aires visuelles primaires (17 et 18) ont été extensivement étudiées. L’implication dans le traitement du deuxième ordre de l’aire dédiée à la perception du mouvement, le Sulcus syprasylvien postéro-médian latéral (PMLS), n’est pas encore connue. Pour ce faire, nous avons étudié les profils de réponse des neurones du PMLS évoqués par des stimuli dont la composante dynamique était de deuxième ordre. Les profils de réponses au mouvement de deuxième ordre sont très similaires au premier ordre, bien que moins sensibles. Nos données suggèrent que la perception du mouvement par le PMLS serait de type form-cue invariant. En somme, les résultats démontrent que le PMLS permet un traitement plus complexe du mouvement du deuxième ordre et sont en accord avec son rôle privilégié dans la perception du mouvement.Visual perception is not limited to the perception of the quantity of light that reaches the retina. The natural scene is in fact composed of contrast and texture variations which are classified as second-order information (in opposition to first-order for luminance). Moreover, second-order motion (spatiotemporal variation of contrast or texture) can easily be detected in several different species even though it cannot be explained by motion detection mechanisms such as the energy model (Adelson and Bergen). Indeed, second-order motion does not involve any luminance variation and cannot be detected by a classical receptor field based on an energy model. Three models are proposed for second-order detection: a filter-rectify-filter circuit, feature-tracking mechanisms or the presence of early non-linearity in the visual system. It was suggested that first- and second-order decoding are performed by distinct pathways. This theory is still debated, but it is generally accepted that they may be partially separated in the early stages of the visual systems. The majority of electrophysiological studies on second-order perception were performed on monkeys and cats. However, even if the cat’s area 17 and 18 responses were greatly studied, the motion dedicated region, the Posteromedial lateral suprasylvian sulcus (PMLS), is still to be evaluated. We performed extracellular recordings in the PMLS to measure the response profiles of its composing neurons to second-order motion. PMLS first- and second-order profiles are similar, but second-order tunings are less selective. Our data suggest that the PMLS performs form-cue invariant processing and accomplishes a more complex decoding of second-order motion