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Probing Nonclassicality of Two-Mode SU(2) Generator Based on Quantum Fisher Information
摘要： Nonclassicality is an essential but still open question in quantum mechanics. Here, utilizing the maximum value of quantum Fisher information, we suggest a new version of the nonclassical criterion for SU(2) generator realized by two bosonic modes. As an application of the criterion, the system of two coupled nonlinear nanomechanical resonators is considered. And the nonclassicality of the phonon state in the dynamical evolution is explored. The system has a dynamical phase transition from the tunnelling phase to the self-trapping phase by tuning the coupling strength. It is found that for the tunnelling phase, the phonon state is nonclassical in the full time evolution. And for the self-trapping phase, the evolved phonon state is still nonclassical in the full time with a relatively large coupling strength, while it is nonclassical i n the most of time (but not all) with a small coupling strength. Quantum coherence has distinct di?erent behaviors in the two phases.
关键词： quantum Fisher information,coherence,nonclassicality
更新于2025-09-09 09:28:46
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Experimental evidence of a very thin superconducting layer in epitaxial indium nitride
摘要： Indium nitride is one of the very few semiconductors which is known to have a superconducting phase at temperatures of Tc > 1 K. Superconductivity occurs in a window of carrier densities of approximately 1018–1020 cm?3. This is a very low density when compared to other superconductors (i.e. metals, alloys, high Tc oxides) and thus raises interesting fundamental questions as well as technological possibilities. In this paper we address one key question about the dimensionality of the superconducting state of InN by using angle dependent critical field measurements. Our samples were grown by two different growth techniques (chemical vapour deposition and plasma-assisted molecular beam epitaxy) on c-oriented sapphire, with and without a GaN buffer layer. In both cases we find that for film thicknesses much larger than the coherence length d ? ξ, the angle dependence of the critical field (down to T < 280 mK) with respect to the c-axis continues to be clearly two-dimensional, demonstrating a characteristic cusp when the angle crosses 90° with respect to the c-axis. This indicates that the superconducting electrons are most likely confined to a layer much thinner than the thickness of the InN film. Further we find the magnitude of the gap to be 2Δ(0)/kBTc = 3.6, very close to the BCS prediction.
关键词： indium nitride,penetration depth,angle dependent critical field,coherence length,critical current,superconductivity
更新于2025-09-09 09:28:46
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Shearlet-Based Feature Extraction for the Detection and Classification of Age-Related Macular Degeneration in Spectral Domain Optical Coherence Tomography Images
摘要： Age-related macular degeneration (AMD) is an eye disease that usually affects central vision in people older than 50 years owing to accumulation of fluid in the macular region of the retina. Optical coherence tomography (OCT) is an imaging modality that is being widely used nowadays for the detection of abnormalities in the eye. In this work, a shearlet transformYbased method is proposed for automated detection of AMD. The 2-dimensional horizontal slices of spectral domain OCT imaging data are used as input images. Images are first converted to gray scale and denoised using bilateral filter. Denoised images are decomposed by applying shearlet transform and 10 textural features are extracted from the cooccurrence matrices of high-frequency transform coefficients. Based on these features, the OCT images are classified as normal or AMD using support vector machine and k-nearest neighbor classifiers. Results obtained using shearlet-based features are compared with that of wavelet transformYbased features. Best results are obtained when shearlet-based features are classified using support vector machine.
关键词： Shearlet transform,Wavelet transform,Support vector machine,Optical coherence tomography,K-nearest neighbor,Age-related macular degeneration
更新于2025-09-09 09:28:46
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Optical correlation-domain reflectometry without optical frequency shifter
摘要： To achieve distributed re?ectivity measurements along an optical ?ber, we developed a simpli?ed cost-effective con?guration for optical correlation- (or coherence-) domain re?ectometry based on a synthesized optical coherence function using sinusoidal modulation. By excluding the conventional optical heterodyne detection that accompanies the frequency shift (without using an acousto-optic modulator) and by exploiting the foot of the electrical Fresnel re?ection spectrum, the electrical bandwidth required for signal processing is lowered to several megahertz. We evaluate the basic system performance and demonstrate its high-speed operation (10 ms for one scan) by tracking a moving re?ection point in real time.
关键词： optical correlation-domain re?ectometry,distributed re?ectivity measurements,optical coherence function,sinusoidal modulation
更新于2025-09-09 09:28:46
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Coherent and incoherent bands in La and Rh doped
摘要： In Sr2IrO4 and Sr3Ir2O7, correlations, magnetism, and spin-orbit coupling compete on similar energy scales, creating a new context to study metal-insulator transitions (MIT). We use here angle-resolved photoemission to investigate the MIT as a function of hole and electron doping in Sr3Ir2O7, obtained respectively by Ir/Rh and Sr/La substitutions. We show that there is a clear reduction as a function of doping of the gap between a lower and upper band on both sides of the Fermi level, from 0.2 to 0.05 eV. Although these two bands have a counterpart in band structure calculations, they are characterized by a very different degree of coherence. The upper band exhibits clear quasiparticle peaks, while the lower band is very broad and loses weight as a function of doping. Moreover, their ARPES spectral weights obey different periodicities, reinforcing the idea of their different nature. We argue that a very similar situation occurs in Sr2IrO4 and conclude that the physics of the two families is essentially the same.
关键词： coherence,Sr3Ir2O7,metal-insulator transitions,incoherence,angle-resolved photoemission,doping
更新于2025-09-09 09:28:46
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Spontaneous Coronary Artery Dissection in a Man With a Novel Missense Mutation in SMAD2 Treated by Optical Coherence Tomography–Guided Percutaneous Coronary Intervention
摘要： A 52-year-old man was admitted with anterior ST-segment elevation myocardial infarction after lifting heavy weights. Urgent coronary angiography showed mild narrowing of the mid left anterior descending artery (LAD). However, 4 days later, ventricular fibrillation occurred. After resuscitation, the mid LAD appeared 'collapsed.' Intracoronary imaging with optical coherence tomography revealed a false lumen extending from the left main coronary artery to the distal LAD and 2 intimal tears at the distal LMCA and mid LAD. Optical coherence tomography–guided implantation of 3 drug-eluting stents was performed, aiming to seal both intimal tears and to strut the collapsed intima. Upon clinical examination, enlarged arm span, reduced upper segment–to–lower segment ratio, broad uvula, pes plani, pectus asymmetry, and mild scoliosis were observed. Additional magnetic resonance angiography did not show signs of fibromuscular dysplasia, aortic aneurysms, or arterial dilatation, but tortuosity of the common iliac arteries and circle of Willis was noted. On the basis of these clinical and vascular features, reminiscent of Loeys-Dietz syndrome, genetic analysis identified a novel missense mutation, c.1082A>C (p.[Asn361Thr]), in the MH2 domain of SMAD2. Myocardial infarction with nonobstructive coronary arteries was caused by a type 2 spontaneous coronary artery dissection (SCAD). Although conservative management is preferred because favorable healing occurs in the vast majority, and percutaneous coronary intervention is challenging, recurrence of myocardial infarction and sudden cardiac death are feared complications. Intravascular imaging by OCT might improve technical success and outcome of percutaneous coronary intervention for SCAD when needed (1–3). The underlying arteriopathy should always be sought. There is a strong association of fibromuscular dysplasia and SCAD. Inherited connective tissue disorders such as Marfan, Ehler-Danlos, and Loeys-Dietz syndromes should be considered as well. All patients with SCAD should undergo a thorough history, clinical examination, and imaging of the extracoronary arteries. Subsequent genetic testing can be considered in selected cases. Recently, loss-of-function SMAD2 mutations have been shown to cause a wide spectrum of aortic and arterial aneurysmal disease (4). This case represents the first documented SCAD in a SMAD2 mutation carrier.
关键词： spontaneous coronary artery dissection,optical coherence tomography,SMAD2,percutaneous coronary intervention,Loeys-Dietz Syndrome
更新于2025-09-09 09:28:46
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - Fully convolutional network and graph-based method for co-segmentation of retinal layer on macular OCT images
摘要： Retinal layer segmentation in optical coherence tomography (OCT) images is crucial for the diagnosis and study of retinal diseases. Graph-based methods are commonly used in layer segmentation. However, most of these methods require a lot of human efforts for determining an appropriate model to compute good edge weights. In this paper, we propose a novel automatic method for segmenting retinal layers in macular OCT images. Specially, we propose a new fully convolutional deep learning architecture with a side output layer to directly learn optimal graph-edge weights from raw pixels. The architecture can automatically learn multi-scale and multi-level features to generate accurate boundary probabilities as good edge weights without hand-crafted appropriate models. The boundaries are finalized by using graph segmentation method. The proposed method is evaluated on a dataset with 130 OCT B-scans. The experimental results show the mean absolute boundary positioning differences are 1.48±0.34 pixel.
关键词： fully convolutional network,retinal layer segmentation,graph-based framework,Optical coherence tomography (OCT)
更新于2025-09-09 09:28:46
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Demonstration of Triband Multi-Focal Imaging with Optical Coherence Tomography
摘要： We demonstrate an extended depth of focus optical coherence tomography (OCT) system based on the use of chromatic aberration to create displaced focal planes in the sample. The system uses a wavelength-swept source tuning over three spectral bands and three separate interferometers, each of which interfaces to a single illumination/collection ?ber. The resulting three imaged volumes are merged in post-processing to generate an image with a larger depth of focus than is obtained from each band individually. The improvements are demonstrated in structural imaging of a porous phantom and a lipid-cleared murine brain, and by angiographic imaging of human skin. By using a coaxial approach with Gaussian beams, this approach enables an extended focus with relatively simple microscope optics and data-merging algorithms.
关键词： optical coherence tomography,chromatic focal shift,multi-focal imaging
更新于2025-09-09 09:28:46
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In Vivo Quantification of Retinal Changes Associated With Drusen in Age-Related Macular Degeneration
摘要： PURPOSE. Drusen alters retinal architecture in early age-related macular degeneration (AMD). However, abnormalities also may exist in drusen-free areas of the AMD retina. This study examines retinal thickness above drusen relative to drusen-free areas in the same patient and a normal population. METHODS. Patients with early to intermediate AMD (n ? 122) or no disease (n ? 30) were examined at the Center for Eye Health. Spectral domain optical coherence tomography (SD-OCT) scans through single, isolated druse (n ? 125) or con?uent drusen (n ? 54) were obtained. The thickness of individual retinal layers was measured above the druse and in a drusen-free area, 150 lm from the drusen edge. RESULTS. Intraeye comparisons found total retinal thickness above drusen was 16 6 0.6% less than drusen-free areas. Thinning was mostly in the retinal pigment epithelium/photoreceptor layer (32 6 1% reduction) and the outer nuclear layer (22 6 1% reduction). Con?uent drusen showed similar thinning of the outer retina as well as inner retina loss (5%). Thinning was strongly correlated with drusen height, but only modestly correlated with drusen width. When compared to the normal population, retinal thickness above drusen and drusen-free areas were signi?cantly reduced. CONCLUSIONS. We con?rm outer retina thinning above drusen in early/intermediate AMD compared to drusen-free areas in the same retina or a normal population. Interestingly, drusen-free areas in AMD patients were not the same as control patients suggesting ‘‘normal’’ areas of the AMD retina are abnormal. The strong correlation between retinal thinning and drusen height, rather than width, suggests current grading systems for AMD may need re?nement.
关键词： drusen,age-related macular degeneration,optical coherence tomography,retinal thickness
更新于2025-09-09 09:28:46
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The Negative Cone Mosaic: A New Manifestation of the Optical Stiles-Crawford Effect in Normal Eyes
摘要： The purpose of this study was to describe a previously unreported manifestation of the optical Stiles-Crawford effect (oSCE) in normal eyes. In a cohort of 50 normal subjects, the directional reflectance of cones in the retinal periphery was explored by flood-illuminated adaptive optics (FIAO) and optical coherence tomography (OCT). In 32 eyes (64%), off-axis FIAO images of the retinal periphery (~15–208 from the fovea) showed variably sized patches of hyporeflective dots (called here negative mosaic) coexisting with hyperreflective (positive) cones. In nine cases, shifting the entry pupil toward the optical axis restored the positive cone mosaic, with a point-by-point correspondence between positive and negative mosaics. Rods remained hyperreflective around negative and positive cones. These changes were paralleled by changes of the OCT reflectance of the cone outer segment tips and, to a lesser extent, of the inner/outer segment limit. By en face FIAO imaging of the retina, the contrast of cones over rods may be strongly dependent on the entry pupil to such an extent that their reflectance is lower than that of rods. We hypothesized that the negative cone mosaic aspect results from the differential Stiles-Crawford effect of cones and rods. Cone reflectance by en face FIAO parallels the reflectance from the cone outer segment tip line and to a lesser extent of the inner/outer segment limit by OCT. Taking this into account, the oSCE is of importance for the interpretation of high-resolution images of photoreceptors.
关键词： photoreceptors,adaptive optics,optical coherence tomography,optical Stiles-Crawford effect
更新于2025-09-09 09:28:46