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Author Wuensch, W.; Degiovanni, A.; Calatroni, S.; Korsback, A.; Djurabekova, F.; Rajamaki, R.; Giner-Navarro, J.
Title Statistics of vacuum breakdown in the high-gradient and low-rate regime Type Journal Article
Year 2017 Publication Physical Review Accelerators and Beams Abbreviated Journal Phys. Rev. Accel. Beams
Volume 20 Issue 1 Pages (up) 011007 - 11pp
Keywords
Abstract In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DCto 12GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.
Address [Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio] CERN, European Org Nucl Res, CH-1211 Geneva, Switzerland, Email: anders.korsback@helsinki.fi
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9888 ISBN Medium
Area Expedition Conference
Notes WOS:000400781300001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3125
Permanent link to this record
 
 
Author Gomis, P.; Perez, A.
Title Decoherence effects in the Stern-Gerlach experiment using matrix Wigner functions Type Journal Article
Year 2016 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 94 Issue 1 Pages (up) 012103 - 11pp
Keywords
Abstract We analyze the Stern-Gerlach experiment in phase space with the help of the matrix Wigner function, which includes the spin degree of freedom. Such analysis allows for an intuitive visualization of the quantum dynamics of the device. We include the interaction with the environment, as described by the Caldeira-Leggett model. The diagonal terms of the matrix provide us with information about the two components of the state that arise from interaction with the magnetic field gradient. In particular, from the marginals of these components, we obtain an analytical formula for the position and momentum probability distributions in the presence of decoherence that shows a diffusive behavior for large values of the decoherence parameter. These features limit the dynamics of the present model. We also observe the decay of the nondiagonal terms with time and use this fact to quantify the amount of decoherence from the norm of those terms in phase space. From here, we can define a decoherence time scale, which differs from previous results that make use of the same model. We analyze a typical experiment and show that, for that setup, the decoherence time is much smaller than the characteristic time scale for the separation of the two beams, implying that they can be described as an incoherent mixture of atoms traveling in the up and down directions with opposite values of the spin projection. Therefore, entanglement is quickly destroyed in the setup we analyzed.
Address [Gomis, P.] Univ Valencia, CSIC, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: Pablo.Gomis@uv.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:000378909000003 Approved no
Is ISI yes International Collaboration no
Call Number IFIC @ pastor @ Serial 2739
Permanent link to this record
 
 
Author Perez, A.
Title Asymptotic properties of the Dirac quantum cellular automaton Type Journal Article
Year 2016 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 93 Issue 1 Pages (up) 012328 - 10pp
Keywords
Abstract We show that the Dirac quantum cellular automaton [A. Bisio, G. M. D'Ariano, and A. Tosini, Ann. Phys. (N. Y.) 354, 244 (2015)] shares many properties in common with the discrete-time quantum walk. These similarities can be exploited to study the automaton as a unitary process that takes place at regular time steps on a one-dimensional lattice, in the spirit of general quantum cellular automata. In this way, it becomes an alternative to the quantum walk, with a dispersion relation that can be controlled by a parameter that plays a similar role to the coin angle in the quantum walk. The Dirac Hamiltonian is recovered under a suitable limit. We provide two independent analytical approximations to the long-term probability distribution. It is shown that, starting from localized conditions, the asymptotic value of the entropy of entanglement between internal and motional degrees of freedom overcomes the known limit that is approached by the quantum walk for the same initial conditions and is similar to the ones achieved by highly localized states of the Dirac equation.
Address [Perez, A.] Univ Valencia, CSIC, IFIC, Dept Fis Teor, E-46100 Valencia, Spain
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1050-2947 ISBN Medium
Area Expedition Conference
Notes WOS:000368291600005 Approved no
Is ISI yes International Collaboration no
Call Number IFIC @ pastor @ Serial 2520
Permanent link to this record
 
 
Author Arnault, P.; Di Molfetta, G.; Brachet, M.; Debbasch, F.
Title Quantum walks and non-Abelian discrete gauge theory Type Journal Article
Year 2016 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 94 Issue 1 Pages (up) 012335 - 6pp
Keywords
Abstract A family of discrete-time quantum walks (DTQWs) on the line with an exact discrete U(N) gauge invariance is introduced. It is shown that the continuous limit of these DTQWs, when it exists, coincides with the dynamics of a Dirac fermion coupled to usual U(N) gauge fields in two-dimensional spacetime. A discrete generalization of the usual U(N) curvature is also constructed. An alternate interpretation of these results in terms of superimposed U(1) Maxwell fields and SU(N) gauge fields is discussed in the Appendix. Numerical simulations are also presented, which explore the convergence of the DTQWs towards their continuous limit and which also compare the DTQWs with classical (i.e., nonquantum) motions in classical SU(2) fields. The results presented in this paper constitute a first step towards quantum simulations of generic Yang-Mills gauge theories through DTQWs.
Address [Arnault, Pablo; Debbasch, Fabrice] Univ Paris 06, Univ Paris 04, PSL Res Univ, LERMA,Observ Paris,CNRS,UMR 8112, F-75014 Paris, France, Email: pablo.arnault@upmc.fr;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:000380095000005 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2761
Permanent link to this record
 
 
Author Guo, J.J.; Sun, F.X.; Zhu, D.Q.; Gessner, M.; He, Q.Y.; Fadel, M.
Title Detecting Einstein-Podolsky-Rosen steering in non-Gaussian spin states from conditional spin-squeezing parameters Type Journal Article
Year 2023 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 108 Issue 1 Pages (up) 012435 - 7pp
Keywords
Abstract We present an experimentally practical method to reveal Einstein-Podolsky-Rosen (EPR) steering in non-Gaussian spin states by exploiting a connection to quantum metrology. Our criterion is based on the quantum Fisher information, and uses bounds derived from generalized spin-squeezing parameters that involve measurements of higher-order moments. This leads us to introduce the concept of conditional spin-squeezing parameters, which quantify the metrological advantage provided by conditional states, as well as detect the presence of an EPR paradox.
Address [Guo, Jiajie; Sun, Feng-Xiao; Zhu, Daoquan; He, Qiongyi] Peking Univ, State Key Lab Mesoscop Phys, Sch Phys, Frontiers Sci Ctr Nanooptoelect, Beijing 100871, Peoples R China, Email: manuel.gessner@uv.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:001130449100004 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5905
Permanent link to this record
 
 
Author Degiovanni, A.; Wuensch, W.; Giner Navarro, J.
Title Comparison of the conditioning of high gradient accelerating structures Type Journal Article
Year 2016 Publication Physical Review Accelerators and Beams Abbreviated Journal Phys. Rev. Accel. Beams
Volume 19 Issue 3 Pages (up) 032001 - 6pp
Keywords
Abstract Accelerating gradients in excess of 100 MV/m, at very low breakdown rates, have been successfully achieved in numerous prototype CLIC accelerating structures. The conditioning and operational histories of several structures, tested at KEK and CERN, have been compared and there is clear evidence that the conditioning progresses with the number of rf pulses and not with the number of breakdowns. This observation opens the possibility that the optimum conditioning strategy, which minimizes the total number of breakdowns the structure is subject to without increasing conditioning time, may be to never exceed the breakdown rate target for operation. The result is also likely to have a strong impact on efforts to understand the physical mechanism underlying conditioning and may lead to preparation procedures which reduce conditioning time.
Address [Degiovanni, Alberto; Wuensch, Walter] CERN, European Org Nucl Res, CH-1211 Geneva, Switzerland, Email: walter.wuensch@cern.ch
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9888 ISBN Medium
Area Expedition Conference
Notes WOS:000400274700001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3090
Permanent link to this record
 
 
Author Arnault, P.; Perez, A.; Arrighi, P.; Farrelly, T.
Title Discrete-time quantum walks as fermions of lattice gauge theory Type Journal Article
Year 2019 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 99 Issue 3 Pages (up) 032110 - 16pp
Keywords
Abstract It is shown that discrete-time quantum walks can be used to digitize, i.e., to time discretize fermionic models of continuous-time lattice gauge theory. The resulting discrete-time dynamics is thus not only manifestly unitary, but also ultralocal, i.e., the particle's speed is upper bounded, as in standard relativistic quantum field theories. The lattice chiral symmetry of staggered fermions, which corresponds to a translational invariance, is lost after the requirement of ultralocality of the evolution; this fact is an instance of Meyer's 1996 no-go results stating that no nontrivial scalar quantum cellular automaton can be translationally invariant [D. A. Meyer, J. Stat. Phys. 85, 551 (1996); Phys. Lett. A 223, 337 (1996)]. All results are presented in a single-particle framework and for a (1+1)-dimensional space-time.
Address [Arnault, Pablo; Perez, Armando] Univ Valencia, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: pablo.arnault@ific.uv.es
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:000461896700002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3950
Permanent link to this record
 
 
Author Bru, L.A.; de Valcarcel, G.J.; Di Molfetta, G.; Perez, A.; Roldan, E.; Silva, F.
Title Quantum walk on a cylinder Type Journal Article
Year 2016 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 94 Issue 3 Pages (up) 032328 - 7pp
Keywords
Abstract We consider the two-dimensional alternate quantum walk on a cylinder. We concentrate on the study of the motion along the open dimension, in the spirit of looking at the closed coordinate as a small or “hidden” extra dimension. If one starts from localized initial conditions on the lattice, the dynamics of the quantum walk that is obtained after tracing out the small dimension shows the contribution of several components which can be understood from the study of the dispersion relations for this problem. In fact, these components originate from the contribution of the possible values of the quasimomentum in the closed dimension. In the continuous space-time limit, the different components manifest as a set of Dirac equations, with each quasimomentum providing the value of the corresponding mass. We briefly discuss the possible link of these ideas to the simulation of high-energy physical theories that include extra dimensions. Finally, entanglement between the coin and spatial degrees of freedom is studied, showing that the entanglement entropy clearly overcomes the value reached with only one spatial dimension.
Address [Bru, Luis A.] Univ Politecn Valencia, ITEAM Res Inst, Opt & Quantum Commun Grp, Camino Vera S-N, E-46022 Valencia, Spain
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:000384060700005 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2823
Permanent link to this record
 
 
Author Marquez-Martin, I.; Arnault, P.; Di Molfetta, G.; Perez, A.
Title Electromagnetic lattice gauge invariance in two-dimensional discrete-time quantum walks Type Journal Article
Year 2018 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 98 Issue 3 Pages (up) 032333 - 8pp
Keywords
Abstract Gauge invariance is one of the more important concepts in physics. We discuss this concept in connection with the unitary evolution of discrete-time quantum walks in one and two spatial dimensions, when they include the interaction with synthetic, external electromagnetic fields. One introduces this interaction as additional phases that play the role of gauge fields. Here, we present a way to incorporate those phases, which differs from previous works. Our proposal allows the discrete derivatives, that appear under a gauge transformation, to treat time and space on the same footing, in a way which is similar to standard lattice gauge theories. By considering two steps of the evolution, we define a density current which is gauge invariant and conserved. In the continuum limit, the dynamics of the particle, under a suitable choice of the parameters, becomes the Dirac equation and the conserved current satisfies the corresponding conservation equation.
Address [Marquez-Martin, Ivan; Arnault, Pablo; Di Molfetta, Giuseppe; Perez, Armando] Univ Valencia, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: ivan.marquez@uv.es;
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:000446163200006 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3750
Permanent link to this record
 
 
Author Marquez-Martin, I.; Di Molfetta, G.; Perez, A.
Title Fermion confinement via quantum walks in (2+1)-dimensional and (3+1)-dimensional space-time Type Journal Article
Year 2017 Publication Physical Review A Abbreviated Journal Phys. Rev. A
Volume 95 Issue 4 Pages (up) 042112 - 5pp
Keywords
Abstract We analyze the properties of a two-and three-dimensional quantum walk that are inspired by the idea of a brane-world model put forward by Rubakov and Shaposhnikov [Phys. Lett. B 125, 136 (1983)]. In that model, particles are dynamically confined on the brane due to the interaction with a scalar field. We translated this model into an alternate quantum walk with a coin that depends on the external field, with a dependence which mimics a domain wall solution. As in the original model, fermions (in our case, the walker) become localized in one of the dimensions, not from the action of a random noise on the lattice (as in the case of Anderson localization) but from a regular dependence in space. On the other hand, the resulting quantum walk can move freely along the “ordinary” dimensions.
Address [Marquez-Martin, I.; Di Molfetta, G.; Perez, A.] Univ Valencia, CSIC, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: giuseppe.dimolfetta@lif.univ-mrs.fr
Corporate Author Thesis
Publisher Amer Physical Soc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9926 ISBN Medium
Area Expedition Conference
Notes WOS:000399931500006 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3102
Permanent link to this record