4,016 research outputs found
Review on qudits production and their application to Quantum Communication and Studies on Local Realism
The codification in higher dimensional Hilbert Spaces (whose logical basis
states are dubbed qudits in analogy with bidimensional qubits) presents various
advantages both for Quantum Information applications and for studies on
Foundations of Quantum Mechanics.
Purpose of this review is to introduce qudits, to summarize their application
to Quantum Communication and researches on Local Realism and, finally, to
describe some recent experiment for realizing them.
A Little more in details: after a short introduction, we will consider the
advantages of testing local realism with qudits, discussing both the 3-4
dimensional case (both for maximally and non-maximally entanglement) and then
the extension to an arbitrary dimension. Afterwards, we will discuss the
theoretical results on using qudits for quantum communication, epitomizing the
outcomes on a larger security in Quantum Key Distribution protocols (again
considering separately qutrits, ququats and generalization to arbitrary
dimension). Finally, we will present the experiments performed up to now for
producing quantum optical qudits and their applications. In particular, we will
mention schemes based on interferometric set-ups, orbital angular momentum
entanglement and biphoton polarization. Finally, we will summarize what
hyperentanglement is and its applications
Uniqueness of and pure supergravities in 4D
After proving the impossibility of consistent non-minimal coupling of a real
Rarita-Schwinger gauge field to electromagnetism, we re-derive the necessity of
introducing the graviton in order to couple a complex Rarita-Schwinger gauge
field to electromagnetism, with or without a cosmological term, thereby
obtaining pure supergravity as the only possibility. These results
are obtained with the BRST-BV deformation method around the flat and (A)dS
backgrounds in 4 dimensions. The same method applied to vectors, real spin-3/2 gauge fields and at most one real spinor field also requires
gravity and yields pure supergravity as well as pure
supergravity coupled to a vector supermultiplet, with or without cosmological
terms. Independently from the matter content, we finally derive strong
necessary quadratic constraints on the possible gaugings for an arbitrary
number of spin-1 and spin-3/2 gauge fields, that are relevant for larger
supergravities.Comment: LaTeX, 31 + 1 pages, no figure. v2: Extended discussion at the end of
Section 3, corrected typos and references adde
Large Graph Analysis in the GMine System
Current applications have produced graphs on the order of hundreds of
thousands of nodes and millions of edges. To take advantage of such graphs, one
must be able to find patterns, outliers and communities. These tasks are better
performed in an interactive environment, where human expertise can guide the
process. For large graphs, though, there are some challenges: the excessive
processing requirements are prohibitive, and drawing hundred-thousand nodes
results in cluttered images hard to comprehend. To cope with these problems, we
propose an innovative framework suited for any kind of tree-like graph visual
design. GMine integrates (a) a representation for graphs organized as
hierarchies of partitions - the concepts of SuperGraph and Graph-Tree; and (b)
a graph summarization methodology - CEPS. Our graph representation deals with
the problem of tracing the connection aspects of a graph hierarchy with sub
linear complexity, allowing one to grasp the neighborhood of a single node or
of a group of nodes in a single click. As a proof of concept, the visual
environment of GMine is instantiated as a system in which large graphs can be
investigated globally and locally
Techniques for effective and efficient fire detection from social media images
Social media could provide valuable information to support decision making in
crisis management, such as in accidents, explosions and fires. However, much of
the data from social media are images, which are uploaded in a rate that makes
it impossible for human beings to analyze them. Despite the many works on image
analysis, there are no fire detection studies on social media. To fill this
gap, we propose the use and evaluation of a broad set of content-based image
retrieval and classification techniques for fire detection. Our main
contributions are: (i) the development of the Fast-Fire Detection method
(FFDnR), which combines feature extractor and evaluation functions to support
instance-based learning, (ii) the construction of an annotated set of images
with ground-truth depicting fire occurrences -- the FlickrFire dataset, and
(iii) the evaluation of 36 efficient image descriptors for fire detection.
Using real data from Flickr, our results showed that FFDnR was able to achieve
a precision for fire detection comparable to that of human annotators.
Therefore, our work shall provide a solid basis for further developments on
monitoring images from social media.Comment: 12 pages, Proceedings of the International Conference on Enterprise
Information Systems. Specifically: Marcos Bedo, Gustavo Blanco, Willian
Oliveira, Mirela Cazzolato, Alceu Costa, Jose Rodrigues, Agma Traina, Caetano
Traina, 2015, Techniques for effective and efficient fire detection from
social media images, ICEIS, 34-4
The conjugacy problem of the modular group and the class number of real quadratic number fields
AbstractWe shall discuss the conjugacy problem of the modular group, and show how its solution, in conjunction with a theorem of Olga Taussky can be used to compute the class number of certain real quadratic number fields
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