Spatial entanglement of twin quantum images

We show that spatial entanglement of two twin images obtained by parametric down-conversion is complete, i.e. concerns both amplitude and phase. This is realised through a homodyne detection of these images which allows for measurement of the field quadrature components. EPR correlations are shown to exist between symmetrical pixels of the two images. The best possible correlation is obtained by adjusting the phase of the local oscillator field (LO) in the area of maximal amplification. The results for quadrature components hold unchanged even in absence of any input image i.e. for pure parametric fluorescence. In this case they are not related to intensity and phase fluctuations.Comment: 19 pages, 2 figure

Space-time coupling in the up-conversion of broadband down-converted light

We investigate the up-conversion process of broadband light from parametric down-conversion (PDC), focusing on the spatio-temporal spectral properties of the sum-frequency generated (SFG) radiation. We demonstrate that the incoherent component of the SFG spectrum is characterized by a skewed geometry in space-time, which originates from a compensation between the group-velocity mismatch and the spatial walk-off of the fundamental and the SFG fields. The results are illustrated both by a theoretical modeling of the optical system and by experimental measurements.Comment: 11 pages, 9 figures. arXiv admin note: text overlap with arXiv:1308.236

Spatio-temporal entanglement of twin photons: an intuitive picture

We draw an intuitive picture of the spatio-temporal properties of the entangled state of twin photons, where they are described as classical wave-packets. This picture predicts a precise relation between their temporal and transverse spatial separations at the crystal output. The space-time coupling described by classical arguments turns out to determine in a precise way the spatio-temporal structure of the quantum entanglement, analysed by means of the biphotonic correlation and of the Schmidt dimensionality of the entanglement.Comment: 12 pages, 3 figure

Coherence properties of high-gain twin beams generated in pump-depletion regime

Twin-beam coherence properties are analyzed both in the spatial and spectral domains at high-gain regime including pump depletion. The increase of the size of intensity auto- and cross-correlation areas at increasing pump power is replaced by a decrease in the pump depletion regime. This effect is interpreted as a progressive loss in the mode selection occurring at high-gain amplification. The experimental determination of the number of spatio-spectral modes from $g^{(2)}$-function measurements confirms this explanation.Comment: 7 pages, 7 figure

Spatial entanglement of twin quantum images

We show that the spatial entanglement of two twin images obtained by parametric down conversion is complete, i.e., concerns both amplitude and phase. By considering a homodyne detection scheme, which allows comparison of field quadrature components of the two images pixel by pixel, Einstein-Podolsky Rosen correlations are shown to exist between symmetrical pixels of the two images. The best possible correlation is obtained by adjusting the phase profile of the local oscillator in the amplification area. The results for quadrature components hold even in the absence of any input image, i.e., for pure parametric fluorescence. In this case, they are not related to intensity and phase fluctuations

Seasonality and Sleep: A Clinical Study on Euthymic Mood Disorder Patients

Background. Research on mood disorders has progressively focused on the study of seasons and on the mood in association with them during depressive or manic episodes yet few studies have focused on the seasonal fluctuation that characterizes the patient's clinical course both during an illness episode and during euthymic periods. Methods. 113 euthymic outpatients 46 affected by major recurrent depression and 67 affected by bipolar disorder were recruited. We evaluated the impact of clinical “rhythmical” factors: seasonality, sleep disturbance, and chronotype. Patients completed the SPAQ+ questionnaire, the MEQ questionnaire, and the medical outcomes study (MOS) sleep scale. We used t-test analyses to compare differences of clinical “rhythmical” and sociodemographic variables and of differences in the assessment scales among the diagnostic groups. Results. Patients reporting a family history for mood disorders have higher fluctuations throughout seasons. Sleep disturbance is more problematic in unipolars when compared to bipolars. Conclusions. Sleep, light, and seasonality seem to be three interconnected features that lie at the basis of chronobiology that, when altered, have an important effect both on the psychopathology and on the treatment of mood disorders

Anthracene/tetracene cocrystals as novel fluorophores in thin-film luminescent solar concentrators

Efficient thin-film luminescent solar concentrators (LSCs) were fabricated using tetracene-doped anthracene cocrystals as novel fluorescent systems dispersed in a poly(methyl methacrylate) matrix. The LSC device efficiency ηLSC was found to reach 2.50%, with an optical efficiency ηopt in excess of 23% and a concentration factor C of 0.83%

Angulation and curvature of aortic landing zone affect implantation depth in transcatheter aortic valve implantation

: In transcatheter aortic valve implantation (TAVI), final device position may be affected by device interaction with the whole aortic landing zone (LZ) extending to ascending aorta. We investigated the impact of aortic LZ curvature and angulation on TAVI implantation depth, comparing short-frame balloon-expanding (BE) and long-frame self-expanding (SE) devices. Patients (n = 202) treated with BE or SE devices were matched based on one-to-one propensity score. Primary endpoint was the mismatch between the intended (HPre) and the final (HPost) implantation depth. LZ curvature and angulation were calculated based on the aortic centerline trajectory available from pre-TAVI computed tomography. Total LZ curvature ( kLZ,tot ) and LZ angulation distal to aortic annulus ( αLZ,Distal ) were greater in the SE compared to the BE group (P < 0.001 for both). In the BE group, HPost was significantly higher than HPre at both cusps (P < 0.001). In the SE group, HPost was significantly deeper than HPre only at the left coronary cusp (P = 0.013). At multivariate analysis, αLZ,Distal was the only independent predictor (OR = 1.11, P = 0.002) of deeper final implantation depth with a cut-off value of 17.8°. Aortic LZ curvature and angulation significantly affected final TAVI implantation depth, especially in high stent-frame SE devices reporting, upon complete release, deeper implantation depth with respect to the intended one