Fidelity Between Partial States as Signature of Quantum Phase Transitions

We introduce a partial state fidelity approach to quantum phase transitions. We consider a superconducting lattice with a magnetic impurity inserted at its centre, and look at the fidelity between partial (either one-site or two-site) quantum states. In the vicinity of the point of the quantum phase transition, we observe a sudden drop of the fidelity between two one-site partial states corresponding to the impurity location and its close vicinity. In the case of two-site states, the fidelity reveals the transition point as long as one of the two electron sites is located at the impurity, while the other lies elsewhere in the lattice. We also determine the Uhlmann mixed state geometric phase, recently introduced in the study of the structural change of the system state eigenvectors in the vicinity of the lines of thermal phase transitions, and find it to be trivial, both for one- and two-site partial states, except when an electron site is at the impurity. This means that the system partial state eigenvectors do not contribute significantly to the enhanced state distinguishability around the point of this quantum phase transition. Finally, we use the fidelity to analyze the total amount of correlations contained within a composite system, showing that, even for the smallest two-site states, it features an abrupt quantitative change in the vicinity of the point of the quantum phase transition.Comment: 11 pages, 5 figure

Cross-Task Transfer for Geotagged Audiovisual Aerial Scene Recognition

Aerial scene recognition is a fundamental task in remote sensing and has recently received increased interest. While the visual information from overhead images with powerful models and efficient algorithms yields considerable performance on scene recognition, it still suffers from the variation of ground objects, lighting conditions etc. Inspired by the multi-channel perception theory in cognition science, in this paper, for improving the performance on the aerial scene recognition, we explore a novel audiovisual aerial scene recognition task using both images and sounds as input. Based on an observation that some specific sound events are more likely to be heard at a given geographic location, we propose to exploit the knowledge from the sound events to improve the performance on the aerial scene recognition. For this purpose, we have constructed a new dataset named AuDio Visual Aerial sceNe reCognition datasEt (ADVANCE). With the help of this dataset, we evaluate three proposed approaches for transferring the sound event knowledge to the aerial scene recognition task in a multimodal learning framework, and show the benefit of exploiting the audio information for the aerial scene recognition. The source code is publicly available for reproducibility purposes.Comment: ECCV 202

A higher quantum bound for the V\'ertesi-Bene-Bell-inequality and the role of POVMs regarding its threshold detection efficiency

Recently, V\'{e}rtesi and Bene [Phys. Rev. A. {\bf 82}, 062115 (2010)] derived a two-qubit Bell inequality, $I_{CH3}$, which they show to be maximally violated only when more general positive operator valued measures (POVMs) are used instead of the usual von Neumann measurements. Here we consider a general parametrization for the three-element-POVM involved in the Bell test and obtain a higher quantum bound for the $I_{CH3}$-inequality. With a higher quantum bound for $I_{CH3}$, we investigate if there is an experimental setup that can be used for observing that POVMs give higher violations in Bell tests based on this inequality. We analyze the maximum errors supported by the inequality to identify a source of entangled photons that can be used for the test. Then, we study if POVMs are also relevant in the more realistic case that partially entangled states are used in the experiment. Finally, we investigate which are the required efficiencies of the $I_{CH3}$-inequality, and the type of measurements involved, for closing the detection loophole. We obtain that POVMs allow for the lowest threshold detection efficiency, and that it is comparable to the minimal (in the case of two-qubits) required detection efficiency of the Clauser-Horne-Bell-inequality.Comment: 11 Pages, 16 Figure

Multimode Hong-Ou-Mandel Interferometry

We review some recent experiments based upon multimode two-photon interference of photon pairs created by spontaneous parametric down-conversion. The new element provided by these experiments is the inclusion of the transverse spatial profiles of the pump, signal and idler fields. We discuss multimode Hong-Ou-Mandel interference, and show that the transverse profile of the pump beam can be manipulated in order to control two-photon interference. We present the basic theory and experimental results as well as several applications to the field of quantum information.Comment: 20 pages, 14 figures, Brief Review to be published in Modern Physics Letters

Deformed Heisenberg algebra and minimal length

A one-dimensional deformed Heisenberg algebra $[X,P]=if(P)$ is studied. We answer the question: For what function of deformation $f(P)$ there exists a nonzero minimal uncertainty in position (minimal length). We also find an explicit expression for the minimal length in the case of arbitrary function of deformation.Comment: to be published in JP

Identificação e diversidade de bactérias promotoras do crescimento vegetal associadas ao girassol.

Estudos de associações entre microrganismos promotores do crescimento em plantas apresentam um enorme potencial devido aos benefícios dados sobre a produtividade. A crescente importância econômica da cultura do girassol, bem como a necessidade de cultivá-lo em diversos ambientes, torna interessante o estudo da sua interação com Bactérias Promotoras do Crescimento Vegetal (BPCV) que possam ser utilizadas sob diferentes condições de solo. No presente trabalho foram utilizadas a técnica seqüenciamento do gene 16S RNAr e de RAPD para o posicionamento filogenético e a determinação da diversidade genotípica de bactérias promotoras do crescimento vegetal associadas à cultura do girassol. Os isolados foram obtidos de amostras da rizosfera, raiz, capítulo e colmo de duas cultivares girassol: Hélio 251 e Aguará 3. A extração de DNA foi realizada utilizando fenol-clorofórmio-álcool isoamílico e a amplificação das seqüências 16S RNAr dos isolados foi realizada com os iniciadores 27F e 778R, e submetidas ao sequenciamento em seqüenciador automático MegaBace 1000. Marcadores moleculares de RAPD foram obtidos para cada BPCV pelo uso dos iniciadores P2, P3, M13 e 1254, o os perfis polimórficos foram utilizados para a construção de um dendrograma de similaridade pelo método UPGMA a partir do coeficiente de similaridade de Jaccard. As sequências do gene 16S RNAr obtidas foram submetidas a uma análise filogenética hierárquica utilizando o software RDP-classifier para derterminação dos prováveis gêneros. As seqüências também foram submetidas a uma análise filogenética por inferência bayesiana utilizando espécies-tipo dos gêneros identificados, para identificação das espécies mais prováveis. A análise da diversidade destes isolados por marcadores RAPD permitiu identificar 13 clusters a 85% de similaridade, sendo possível identificar o agrupamento de isolados com relação ao genótipo e ao tecido vegetal de origem. A análise filogenética permitiu posicionar 42 isolados dentro do gênero Bacillus, compreendendo as espécies B. subtilis, B. amyloliquefaciens, B. cereus, B. thuringiensis, B. pumilus e B. megaterium. Somente 3 isolados foram classificados fora do gênero Bacillus, sendo posicionados no gênero Methylobacterium e relacionados à espécie M. komagatae.Resumo, 1928-1

Nitrous oxide fluxes in an integrated crop-livestock-forest system in Sinop-MT.

The objective of this study was to evaluate the mitigation potential of crop-livestock-forest integration system (ICLF) or monoculture forest, farming and grazing, check the seasonal differences in emissions between them and the effect of management operations of cultures on N2O fluxes

Criticality in the 2+1-dimensional compact Higgs model and fractionalized insulators

We use a novel method of computing the third moment M_3 of the action of the 2+1-dimensional compact Higgs model in the adjoint representation with q=2 to extract correlation length and specific heat exponents nu and alpha, without invoking hyperscaling. Finite-size scaling analysis of M_3 yields the ratio (1+alpha)/nu and 1/nu separately. We find that alpha and nu vary along the critical line of the theory, which however exhibits a remarkable resilience of Z_2 criticality. We propose this novel universality class to be that of the quantum phase transition from a Mott-Hubbard insulator to a charge-fractionalized insulator in two spatial dimensions.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

Fermion zero mode and superfluid weight

We propose one possible mechanism for deconfinement based on an SU(2) slave-boson theory. Resorting to an effective field theory approach, we show that introduction of an isospin interaction potential gives rise to a fermion zero mode in an instanton-hedgehog configuration. As a result, meron-type vortices are allowed. We demonstrate how emergence of such vortices results in the doping-independent decreasing ratio of superfluid weight