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Author |
Fernandez Casani, A.; Orduña, J.M.; Sanchez, J.; Gonzalez de la Hoz, S. |
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Title |
A Reliable Large Distributed Object Store Based Platform for Collecting Event Metadata |
Type |
Journal Article |
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Year |
2021 |
Publication |
Journal of Grid Computing |
Abbreviated Journal |
J. Grid Comput. |
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Volume |
19 |
Issue |
3 |
Pages |
39 - 19pp |
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Keywords |
Grid computing; Hadoop file system; Object-Based storage |
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Abstract |
The Large Hadron Collider (LHC) is about to enter its third run at unprecedented energies. The experiments at the LHC face computational challenges with enormous data volumes that need to be analysed by thousands of physics users. The ATLAS EventIndex project, currently running in production, builds a complete catalogue of particle collisions, or events, for the ATLAS experiment at the LHC. The distributed nature of the experiment data model is exploited by running jobs at over one hundred Grid data centers worldwide. Millions of files with petabytes of data are indexed, extracting a small quantity of metadata per event, that is conveyed with a data collection system in real time to a central Hadoop instance at CERN. After a successful first implementation based on a messaging system, some issues suggested performance bottlenecks for the challenging higher rates in next runs of the experiment. In this work we characterize the weaknesses of the previous messaging system, regarding complexity, scalability, performance and resource consumption. A new approach based on an object-based storage method was designed and implemented, taking into account the lessons learned and leveraging the ATLAS experience with this kind of systems. We present the experiment that we run during three months in the real production scenario worldwide, in order to evaluate the messaging and object store approaches. The results of the experiment show that the new object-based storage method can efficiently support large-scale data collection for big data environments like the next runs of the ATLAS experiment at the LHC. |
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Address |
[Fernandez Casani, Alvaro; Sanchez, Javier; Gonzalez de la Hoz, Santiago] Univ Valencia, Inst Fis Corpuscular IFIC, Burjassot, Spain, Email: alvaro.fernandez@ific.uv.es; |
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Springer |
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English |
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ISSN  |
1570-7873 |
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Notes |
WOS:000692413100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4953 |
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Author |
Nzongani, U.; Zylberman, J.; Doncecchi, C.E.; Perez, A.; Debbasch, F.; Arnault, P. |
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Title |
Quantum circuits for discrete-time quantum walks with position-dependent coin operator |
Type |
Journal Article |
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Year |
2023 |
Publication |
Quantum Information Processing |
Abbreviated Journal |
Quantum Inf. Process. |
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Volume |
22 |
Issue |
7 |
Pages |
270 - 46pp |
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Keywords |
Quantum walks; Quantum circuits; Quantum simulation |
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Abstract |
The aim of this paper is to build quantum circuits that implement discrete-time quantum walks having an arbitrary position-dependent coin operator. The position of the walker is encoded in base 2: with n wires, each corresponding to one qubit, we encode 2(n) position states. The data necessary to define an arbitrary position-dependent coin operator is therefore exponential in n. Hence, the exponentiality will necessarily appear somewhere in our circuits. We first propose a circuit implementing the position-dependent coin operator, that is naive, in the sense that it has exponential depth and implements sequentially all appropriate position-dependent coin operators. We then propose a circuit that “transfers” all the depth into ancillae, yielding a final depth that is linear in n at the cost of an exponential number of ancillae. Themain idea of this linear-depth circuit is to implement in parallel all coin operators at the different positions. Reducing the depth exponentially at the cost of having an exponential number of ancillae is a goal which has already been achieved for the problem of loading classical data on a quantum circuit (Araujo in Sci Rep 11:6329, 2021) (notice that such a circuit can be used to load the initial state of the walker). Here, we achieve this goal for the problem of applying a position-dependent coin operator in a discrete-time quantum walk. Finally, we extend the result of Welch (New J Phys 16:033040, 2014) from position-dependent unitaries which are diagonal in the position basis to position-dependent 2 x 2-block-diagonal unitaries: indeed, we show that for a position dependence of the coin operator (the block-diagonal unitary) which is smooth enough, one can find an efficient quantum-circuit implementation approximating the coin operator up to an error epsilon (in terms of the spectral norm), the depth and size of which scale as O(1/epsilon). A typical application of the efficient implementation would be the quantum simulation of a relativistic spin-1/2 particle on a lattice, coupled to a smooth external gauge field; notice that recently, quantum spatial-search schemes have been developed which use gauge fields as the oracle, to mark the vertex to be found (Zylberman in Entropy 23:1441, 2021), (Fredon arXiv:2210.13920). A typical application of the linear-depth circuit would be when there is spatial noise on the coin operator (and hence a non-smooth dependence in the position). |
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Address |
[Nzongani, Ugo; Doncecchi, Carlo-Elia; Arnault, Pablo] Univ Paris Saclay, CNRS, INRIA, Lab Methodes Formelles,ENS Paris Saclay, F-91190 Gif Sur Yvette, France, Email: ugo.nzongani@universite-paris-saclay.fr; |
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Publisher |
Springer |
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English |
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ISSN |
1570-0755 |
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Notes |
WOS:001022408900002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5587 |
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Author |
Vento, V. |
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Title |
Skyrmions at high density |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physics of Particles and Nuclei Letters |
Abbreviated Journal |
Phys. Part. Nuclei Lett. |
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Volume |
15 |
Issue |
4 |
Pages |
367-370 |
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Keywords |
quark; pion; skyrmion; dilation |
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Abstract |
The phase diagram of quantum chromodynamics is conjectured to have a rich structure containing at least three forms of matter: hadronic nuclear matter, quarkyonic matter and quark gluon plasma. We describe its formulation in terms of Skyrme crystals and justify the origin of the quarkyonic phase transition in a chiral-quark model. |
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Address |
[Vento, V.] Univ Valencia, CSIC, Dept Fis Teor IFIC, E-46100 Burjassot, Valencia, Spain, Email: vicente.vento@uv.es |
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Publisher |
Pleiades Publishing Inc |
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English |
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ISSN |
1547-4771 |
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Notes |
WOS:000437770100006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
3651 |
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Author |
Perez, A.; Romanelli, A. |
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Title |
Spatially Dependent Decoherence and Anomalous Diffussion of Quantum Walks |
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Journal Article |
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Year |
2013 |
Publication |
Journal of Computational and Theoretical Nanoscience |
Abbreviated Journal |
J. Comput. Theor. Nanosci. |
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Volume |
10 |
Issue |
7 |
Pages |
1591-1595 |
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Keywords |
Decoherence; Quantum Walk; Non-Translational Invariance |
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Abstract |
We analyze the long time behavior of a discrete time quantum walk subject to decoherence with a strong spatial dependence, acting on one half of the lattice. We show that, except for limiting cases on the decoherence parameter, the quantum walk at late times behaves sub-ballistically, meaning that the characteristic features of the quantum walk are not completely spoiled. Contrarily to expectations, the asymptotic behavior is non Markovian, and depends on the amount of decoherence. This feature can be clearly shown on the long time value of the Generalized Chiral Distribution (GCD). |
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Address |
[Perez, A.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain |
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Publisher |
Amer Scientific Publishers |
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English |
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Edition |
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ISSN |
1546-1955 |
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Notes |
WOS:000322605800007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1528 |
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Author |
Hinarejos, M.; Bañuls, M.C.; Perez, A. |
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Title |
A Study of Wigner Functions for Discrete-Time Quantum Walks |
Type |
Journal Article |
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Year |
2013 |
Publication |
Journal of Computational and Theoretical Nanoscience |
Abbreviated Journal |
J. Comput. Theor. Nanosci. |
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Volume |
10 |
Issue |
7 |
Pages |
1626-1633 |
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Keywords |
Quantum Walk; Wigner Function; Negativity |
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Abstract |
We perform a systematic study of the discrete time Quantum Walk on one dimension using Wigner functions, which are generalized to include the chirality (or coin) degree of freedom. In particular, we analyze the evolution of the negative volume in phase space, as a function of time, for different initial states. This negativity can be used to quantify the degree of departure of the system from a classical state. We also relate this quantity to the entanglement between the coin and walker subspaces. |
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Address |
[Hinarejos, M.; Perez, A.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain |
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Publisher |
Amer Scientific Publishers |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1546-1955 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000322605800014 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1529 |
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