860 research outputs found
General pure multipartite entangled states and the Segre variety
In this paper, we construct a measure of entanglement by generalizing the
quadric polynomial of the Segre variety for general multipartite states. We
give explicit expressions for general pure three-partite and four-partite
states. Moreover, we will discuss and compare this measure of entanglement with
the generalized concurrence.Comment: 5 page
Noncommutative geometrical structures of entangled quantum states
We study the noncommutative geometrical structures of quantum entangled
states. We show that the space of a pure entangled state is a noncommutative
space. In particular we show that by rewritten the conifold or the Segre
variety we can get a -deformed relation in noncommutative geometry. We
generalized our construction into a multi-qubit state. We also in detail
discuss the noncommutative geometrical structure of a three-qubit state.Comment: 7 page
Topological quantum gate entangler for a multi-qubit state
We establish a relation between topological and quantum entanglement for a
multi-qubit state by considering the unitary representations of the Artin braid
group. We construct topological operators that can entangle multi-qubit state.
In particular we construct operators that create quantum entanglement for
multi-qubit states based on the Segre ideal of complex multi-projective space.
We also in detail discuss and construct these operators for two-qubit and
three-qubit states.Comment: 6 page
Compact star clusters of the LMC HII region N11C
Based on imaging and spectroscopy obtained at the ESO NTT telescope and using
an efficient image analysis algorithm, we study the core of the LMC OB
association LH13, particularly the two compact stellar clusters Sk-6641 and HNT
in the HII, region N11C. We resolve Sk-6641 into 15 components and for the
first time the HNT cluster into 70 stars, and derive photometry for the
members. Moreover, from medium resolution spectroscopy we determine the
spectral types for sixteen stars in N11C. We compare the color-magnitude
diagrams of the clusters with that of the field stars and discuss the cluster
ages. With an age of ~100 Myr, the HNT cluster appears significantly older than
the very young (< 5 Myr) Sk-6641 starburst. We suggest that most of the `field'
O-stars in the core of N11C have actually been ejected from Sk-6641 through
dynamical interactions in the compact cluster. The properties of the Sk-6641
and HNT clusters suggest that we are viewing different star formation regions
lying at different distances along the same line of sight.Comment: 12 pages, 8 figure
Jabba: hybrid error correction for long sequencing reads using maximal exact matches
Third generation sequencing platforms produce longer reads with higher error rates than second generation sequencing technologies. While the improved read length can provide useful information for downstream analysis, underlying algorithms are challenged by the high error rate. Error correction methods in which accurate short reads are used to correct noisy long reads appear to be attractive to generate high-quality long reads. Methods that align short reads to long reads do not optimally use the information contained in the second generation data, and suffer from large runtimes. Recently, a new hybrid error correcting method has been proposed, where the second generation data is first assembled into a de Bruijn graph, on which the long reads are then aligned. In this context we present Jabba, a hybrid method to correct long third generation reads by mapping them on a corrected de Bruijn graph that was constructed from second generation data. Unique to our method is that this mapping is constructed with a seed and extend methodology, using maximal exact matches as seeds. In addition to benchmark results, certain theoretical results concerning the possibilities and limitations of the use of maximal exact matches in the context of third generation reads are presented
Generalized Chaplygin gas as geometrical dark energy
The generalized Chaplygin gas provides an interesting candidate for the
present accelerated expansion of the universe. We explore a geometrical
explanation for the generalized Chaplygin gas within the context of brane world
theories where matter fields are confined to the brane by means of the action
of a confining potential. We obtain the modified Friedmann equations,
deceleration parameter and age of the universe in this scenario and show that
they are consistent with the present observational data.Comment: 11 pages, 3 figures, to appear in PR
Localization of gravity in brane world with arbitrary extra dimensions
We study the induced 4-dimensional linearized Einstein field equations in an
m-dimensional bulk space by means of a confining potential. It is shown that in
this approach the mass of graviton is quantized. The cosmological constant
problem is also addressed within the context of this approach. We show that the
difference between the values of the cosmological constant in particle physics
and cosmology stems from our measurements in two different scales, small and
large.Comment: 8 pages. arXiv admin note: substantial text overlap with
arXiv:gr-qc/0408004, arXiv:gr-qc/0607067, arXiv:0704.1035, arXiv:0707.3558,
arXiv:0710.266
Jabba: hybrid error correction for long sequencing reads
Background: Third generation sequencing platforms produce longer reads with higher error rates than second generation technologies. While the improved read length can provide useful information for downstream analysis, underlying algorithms are challenged by the high error rate. Error correction methods in which accurate short reads are used to correct noisy long reads appear to be attractive to generate high-quality long reads. Methods that align short reads to long reads do not optimally use the information contained in the second generation data, and suffer from large runtimes. Recently, a new hybrid error correcting method has been proposed, where the second generation data is first assembled into a de Bruijn graph, on which the long reads are then aligned.
Results: In this context we present Jabba, a hybrid method to correct long third generation reads by mapping them on a corrected de Bruijn graph that was constructed from second generation data. Unique to our method is the use of a pseudo alignment approach with a seed-and-extend methodology, using maximal exact matches (MEMs) as seeds. In addition to benchmark results, certain theoretical results concerning the possibilities and limitations of the use of MEMs in the context of third generation reads are presented.
Conclusion: Jabba produces highly reliable corrected reads: almost all corrected reads align to the reference, and these alignments have a very high identity. Many of the aligned reads are error-free. Additionally, Jabba corrects reads using a very low amount of CPU time. From this we conclude that pseudo alignment with MEMs is a fast and reliable method to map long highly erroneous sequences on a de Bruijn graph
Entanglement measure for general pure multipartite quantum states
We propose an explicit formula for an entanglement measure of pure
multipartite quantum states, then study a general pure tripartite state in
detail, and at end we give some simple but illustrative examples on four-qubits
and m-qubits states.Comment: 5 page
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