406 research outputs found
Tomographic test of Bell's inequality for a time-delocalized single photon
Time-domain balanced homodyne detection is performed on two well-separated
temporal modes sharing a single photon. The reconstructed density matrix of the
two-mode system is used to prove and quantify its entangled nature, while the
Wigner function is employed for an innovative tomographic test of Bell's
inequality based on the theoretical proposal by Banaszek and Wodkiewicz [Phys.
Rev. Lett. 82, 2009 (1999)]. Provided some auxiliary assumptions are made, a
clear violation of Banaszek-Bell's inequality is found.Comment: 7 pages, 3 figures: revised version with additional material;
accepetd for publication in Phys. Rev.
Surgical treatment of necrotizing enterocolitis: when? how?
In 10 years (1981 - 1990) 28 out of 54 neonates (51.8%) with definite necrotizing enterocolitis (NEC) underwenl surgery. Operation was performed al 13.5 ± 8.8 (range 3 38) days of lifc, after 1.7 f 1.5 (range 1 --6) days from the onset of symptoms. Aiming to perform laparotomy before the occurrence of perforation, surgery was liberally indicated in stage IIIa, according to Walsh-Kliegman. Explorative laparotorny (+pcritoneal drainage in 2 cases) was performed in 4 patients with massive intestinal necrosis: all died within 3 days of surgery. In one neonate, only pneumatosis was present and resection was not considered mandatory. Intestinal resection and enterostorny was performed in 17 neonates, 5 of them with perforation; three developed an intestinal stenosis. 6nterostomy was closed after 116.2 f 61.8 days (range 26--193); 11 patients (64.7%) are long-terni survivors. Intestinal resection and primary anastomosis was performed in 6 babics, 3 of them with perforation. Postoperatively, 2 dehiscences and 1 stenosis avere recorded, but all children survived. In our opinion, resection followed by primary anastomosis seans to bc the most salisfactory surgical optio
Experimental demonstration of bosonic commutation relation via superpositions of quantum operations on thermal light fields
We present the experimental realization of a scheme, based on single-photon
interference, for implementing superpositions of distinct quantum operations.
Its application to a thermal light field (a well-categorized classical entity)
illustrates quantum superposition from a new standpoint and provides a direct
and quantitative verification of the bosonic commutation relation between
creation and annihilation operators. By shifting the focus towards operator
superpositions, this result opens interesting alternative perspectives for
manipulating quantum states.Comment: 4 pages, 3 figures, to appear in Physical Review Letter
Subtracting photons from arbitrary light fields: experimental test of coherent state invariance by single-photon annihilation
The operator annihilating a single quantum of excitation in a bosonic field is one of the cornerstones for the interpretation and prediction of the behavior of the microscopic quantum world. Here we present a systematic experimental study of the effects of single-photon annihilation on some paradigmatic light states. In particular, by demonstrating the invariance of coherent states by this operation, we provide the first direct verification of their definition as eigenstates of the photon annihilation operator
Dynamic nuclear polarization at high magnetic fields in liquids
High field dynamic nuclear polarization spectrometer for liquid samples have
been constructed. â–º The field dependence of the Overhauser DNP efficiency has
been measured for the first time up to 9.2 T. â–º High DNP enhancements for
liquid samples have been observed at high magnetic fields. â–º The enhancements
have been compared with results from NMRD, MD and theoretical models. â–º
Coherent and relaxation effects within fast magnetic field changes have been
analyzed
Demonstrating various quantum effects with two entangled laser beams
We report on the preparation of entangled two mode squeezed states of yet
unseen quality. Based on a measurement of the covariance matrix we found a
violation of the Reid and Drummond EPR-criterion at a value of only 0.36\pm0.03
compared to the threshold of 1. Furthermore, quantum state tomography was used
to extract a single photon Fock state solely based on homodyne detection,
demonstrating the strong quantum features of this pair of laser-beams. The
probability for a single photon in this ensemble measurement exceeded 2/3
Mapping coherence in measurement via full quantum tomography of a hybrid optical detector
Quantum states and measurements exhibit wave-like --- continuous, or
particle-like --- discrete, character. Hybrid discrete-continuous photonic
systems are key to investigating fundamental quantum phenomena, generating
superpositions of macroscopic states, and form essential resources for
quantum-enhanced applications, e.g. entanglement distillation and quantum
computation, as well as highly efficient optical telecommunications. Realizing
the full potential of these hybrid systems requires quantum-optical
measurements sensitive to complementary observables such as field quadrature
amplitude and photon number. However, a thorough understanding of the practical
performance of an optical detector interpolating between these two regions is
absent. Here, we report the implementation of full quantum detector tomography,
enabling the characterization of the simultaneous wave and photon-number
sensitivities of quantum-optical detectors. This yields the largest
parametrization to-date in quantum tomography experiments, requiring the
development of novel theoretical tools. Our results reveal the role of
coherence in quantum measurements and demonstrate the tunability of hybrid
quantum-optical detectors.Comment: 7 pages, 3 figure
Cauliflower Mosaic Virus TAV, a Plant Virus Protein That Functions like Ribonuclease H1 and is Cytotoxic to Glioma Cells
Recent comparisons between plant and animal viruses reveal many common principles that underlie how all viruses express their
genetic material, amplify their genomes, and link virion assembly with replication. Cauliflower mosaic virus (CaMV) is not
infectious for human beings. Here, we show that CaMV transactivator/viroplasmin protein (TAV) shares sequence similarity with
and behaves like the human ribonuclease H1 (RNase H1) in reducing DNA/RNA hybrids detected with S9.6 antibody in
HEK293T cells. We showed that TAV is clearly expressed in the cytosol and in the nuclei of transiently transfected human cells,
similar to its distribution in plants. TAV also showed remarkable cytotoxic effects in U251 human glioma cells in vitro. *ese
characteristics pave the way for future analysis on the use of the plant virus protein TAV, as an alternative to human RNAse H1
during gene therapy in human cells
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