284 research outputs found

    Nonexistence of Entanglement Sudden Death in High NOON States

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    We study the dynamics of entanglement in continuous variable quantum systems (CVQS). Specifically, we study the phenomena of Entanglement Sudden Death (ESD) in general two-mode-N-photon states undergoing pure dephasing. We show that for these states, ESD never occurs. These states are generalizations of the so-called High NOON states, shown to decrease the Rayleigh limit of lambda to lambda/N, which promises great improvement in resolution of interference patterns if states with large N are physically realized. However, we show that in dephasing NOON states, the time to reach V_crit, critical visibility, scales inversely with N^2. On the practical level, this shows that as N increases, the visibility degrades much faster, which is likely to be a considerable drawback for any practical application of these states.Comment: 4 pages, 1 figur

    Enhancing image contrast using coherent states and photon number resolving detectors

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    We experimentally map the transverse profile of diffraction-limited beams using photon-number-resolving detectors. We observe strong compression of diffracted beam profiles for high detected photon number. This effect leads to higher contrast than a conventional irradiance profile between two Airy disk-beams separated by the Rayleigh criterion.Comment: 7 pages, 3 figures, accepted for publication in Optics Expres

    Non-communicating hydrocephalus from pork tapeworm obstructing the foramina of Monro and its endoscopic management; a case report from Europe

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    Introduction: Taenia solium is the main causative agent of neurocysticercosis. The tapeworm can manifest inside the ventricles, usually in the form of intracranial hypertension. We present a case of hydrocephalus as a result of a neurocysticercosis lesion obstructing both foramina of Monro. Research question: A comprehensive review of the management is provided, as well as video footage (an invaluable resource to compare, critique and learn with other institutions). Material and methods: A 23-year-old female from Honduras presented with a 7-day complaint of headache. On exam, she was hyperreflexic, but otherwise normal. Magnetic resonance imaging (MRI) revealed a non-specific lesion at the level of the foramina of Monro, with associated hydrocephalus. Additional testing was normal. Results: The patient underwent an endoscopic ventriculoscopy with partial excision of the lesion and subsequent implantation of a ventriculoperitoneal shunt. On postoperative MRI, hydrocephalus resolved and pathological analysis identified the parasite as Taenia solium. Albendazole was administered for 14 days. Discussion and conclusion: Neurocysticercosis should be considered in patients presenting with hydrocephalus, especially those from endemic areas. The long-term prognosis of ventricular neurocysticercosis might be favourable, provided that adequate care is given timely. Endoscopic surgery seems to be effective for the removal of parasitic lesions. However, studies comparing open versus endoscopic surgery are lacking. The majority of cases in the literature correspond to America and Asia. This case shows that neurocysticercosis is also present in Europe, and that a high index of suspicion is necessar

    Creation of NOON states by double Fock-state/Bose-Einstein condensates

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    NOON states (states of the form N>a0>b+0>aN>b|N>_{a}|0>_{b}+|0>_{a}|N>_{b} where aa and bb are single particle states) have been used for predicting violations of hidden-variable theories (Greenberger-Horne-Zeilinger violations) and are valuable in metrology for precision measurements of phase at the Heisenberg limit. We show theoretically how the use of two Fock state/Bose-Einstein condensates as sources in a modified Mach Zender interferometer can lead to the creation of the NOON state in which aa and bb refer to arms of the interferometer and NN is the total number of particles in the two condensates. The modification of the interferometer involves making conditional ``side'' measurements of a few particles near the sources. These measurements put the remaining particles in a superposition of two phase states, which are converted into NOON states by a beam splitter. The result is equivalent to the quantum experiment in which a large molecule passes through two slits. The NOON states are combined in a final beam splitter and show interference. Attempts to detect through which ``slit'' the condensates passed destroys the interference.Comment: 8 pages 5 figure

    Positioning and clock synchronization through entanglement

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    A method is proposed to employ entangled and squeezed light for determining the position of a party and for synchronizing distant clocks. An accuracy gain over analogous protocols that employ classical resources is demonstrated and a quantum-cryptographic positioning application is given, which allows only trusted parties to learn the position of whatever must be localized. The presence of a lossy channel and imperfect photodetection is considered. The advantages in using partially entangled states is discussed.Comment: Revised version. 9 pages, 6 figure

    On building physics-based AI models for the design and SHM of mooring systems

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    Expert systems in industrial processes are modelled using physics-based approaches, data-driven models or hybrid approaches in which however the underlying physical models generally constitute a separate block with respect to the Artificial Intelligence (AI) technique(s). This work applies the novel concept of “imbrication”-a physics-based AI approach-to the mooring system of offshore renewable energy devices to achieve a complete integration of both perspectives. This approach can reduce the size of the training dataset and computational time while delivering algorithms with higher generalization capability and explicability. We first undertake the design of the mooring system by developing a surrogate model coupled with a Bayesian optimiser. Then, we analyse the structural health monitoring of the mooring system by designing a supervised Deep Neural Network architecture. Herein, we describe the characteristics of the imbrication process, analyse preliminary results of our investigation and provide considerations for orienting further research work and sector applicability

    Quinoline- and benzoselenazole-derived unsymmetrical squaraine cyanine dyes: design, synthesis, photophysicochemical features and light-triggerable antiproliferative effects against breast cancer cell lines

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    Photodynamic therapy is an innovative treatment approach broadly directed towards oncological diseases. Its applicability and efficiency are closely related to the interaction of three main components, namely a photosensitizer, light and molecular triplet oxygen, which should drive cell death. Recently, several studies have demonstrated that squaraine cyanine dyes have a set of photophysical and photochemical properties that have made of these compounds’ potential photosensitizers for this therapeutic modality. In the present research work, we describe the synthesis and characterization of four quinoline- and benzoselenazole-derived unsymmetrical squaraine cyanine dyes. Except for the precursor of aminosquaraine dyes, i.e., O-methylated derivative, all dyes were evaluated for their behavior and absorption capacity in different organic and aqueous solvents, their ability to form singlet oxygen, their light-stability, and in vitro phototherapeutic effects against two human breast cancer cell cultures (BT-474 and MCF-7). Regardless of the nature of the used solvents, the synthesized dyes showed intense absorption in the red and near-infrared spectral regions, despite the formation of aggregates in aqueous media. Dyes showed high light-stability against light exposure. Despite the low ability to produce singlet oxygen, aminosquaraine dyes demonstrated worthy in vitro phototherapeutic activity.This research was funded by the European Investment Funds by FEDER/COMPETE/POCI under projects POCI-01-0145-FEDER-006958 (CITAB) and POCI-01-0145-FEDER-007491 (CICS-UBI) and Funds by FCT—Portuguese Foundation for Science and technology, under the projects UIDB/ 04033/2020 (CITAB) and UIDB/ 00616/2020 (CQ-VR). This work was also supported by funds from the Health Sciences Research Center (CICS-UBI) through National Funds by FCT—Foundation for Science and Technology (UID/Multi/00709/2019).The research at iBB was supported by Project UID/NAN/50024/2019 and M-ERA-NET/0002/2015 from FCT. E.L. was supported by the FCT PhD grant SFRH/BD/147645/2019.info:eu-repo/semantics/publishedVersio
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