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Author Bru, L.A.; de Valcarcel, G.J.; Di Molfetta, G.; Perez, A.; Roldan, E.; Silva, F. url  doi
openurl 
  Title Quantum walk on a cylinder Type Journal Article
  Year (down) 2016 Publication Physical Review A Abbreviated Journal Phys. Rev. A  
  Volume 94 Issue 3 Pages 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 Di Molfetta, G.; Perez, A. url  doi
openurl 
  Title Quantum walks as simulators of neutrino oscillations in a vacuum and matter Type Journal Article
  Year (down) 2016 Publication New Journal of Physics Abbreviated Journal New J. Phys.  
  Volume 18 Issue Pages 103038 - 8pp  
  Keywords quantum walks; neutrino oscillations; quantum simulation  
  Abstract We analyze the simulation of Dirac neutrino oscillations using quantum walks, both in a vacuum and in matter. We show that this simulation, in the continuum limit, reproduces a set of coupled Dirac equations that describe neutrino flavor oscillations, and we make use of this to establish a connection with neutrino phenomenology, thus allowing one to fix the parameters of the simulation for a given neutrino experiment. We also analyze how matter effects for neutrino propagation can be simulated in the quantum walk. In this way, important features, such as the MSW effect, can be incorporated. Thus, the simulation of neutrino oscillations with the help of quantum walks might be useful to illustrate these effects in extreme conditions, such as the solar interior or supernovae.  
  Address [Di Molfetta, G.] Univ Valencia, CSIC, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: giuseppe.dimolfetta@lif.univ-mrs.fr  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1367-2630 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000386816100004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2846  
Permanent link to this record
 
 
Author Hinarejos, M.; Bañuls, M.C.; Perez, A. url  doi
openurl 
  Title Wigner formalism for a particle on an infinite lattice: dynamics and spin Type Journal Article
  Year (down) 2015 Publication New Journal of Physics Abbreviated Journal New J. Phys.  
  Volume 17 Issue Pages 013037 - 16pp  
  Keywords Wigner functions; dynamics on a lattice; spin-dependent forces  
  Abstract The recently proposed Wigner function for a particle in an infinite lattice (Hinarejos M, Banuls MC and Perez A 2012 New J. Phys. 14 103009) is extended here to include an internal degree of freedom as spin. This extension is made by introducing a Wigner matrix. The formalism is developed to account for dynamical processes, with or without decoherence. We show explicit solutions for the case of Hamiltonian evolution under a position-dependent potential, and for evolution governed by a master equation under some simple models of decoherence, for which the Wigner matrix formalism is well suited. Discrete processes are also discussed. Finally, we discuss the possibility of introducing a negativity concept for the Wigner function in the case where the spin degree of freedom is included.  
  Address [Hinarejos, M.; Perez, A.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: banulsm@mpq.mpg.de  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1367-2630 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000348759800007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2101  
Permanent link to this record
 
 
Author Hinarejos, M.; Di Franco, C.; Romanelli, A.; Perez, A. url  doi
openurl 
  Title Chirality asymptotic behavior and non-Markovianity in quantum walks on a line Type Journal Article
  Year (down) 2014 Publication Physical Review A Abbreviated Journal Phys. Rev. A  
  Volume 89 Issue 5 Pages 052330 - 7pp  
  Keywords  
  Abstract We investigate the time evolution of the chirality reduced density matrix for a discrete-time quantum walk on a one-dimensional lattice. The matrix is obtained by tracing out the spatial degree of freedom. We analyze the standard case, without decoherence, and the situation in which decoherence appears in the form of broken links in the lattice. By examining the trace distance for possible pairs of initial states as a function of time, we conclude that the evolution of the reduced density matrix is non-Markovian, in the sense defined by Breuer, Laine, and Piilo [Phys. Rev. Lett. 103, 210401 (2009)]. As the level of noise increases, the dynamics approaches a Markovian process. The highest non-Markovianity corresponds to the case without decoherence. The reduced density matrix tends always to a well-defined limit that we calculate, but only in the decoherence-free case is this limit nontrivial.  
  Address [Hinarejos, Margarida; Perez, Armando] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, 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:000336751300003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1807  
Permanent link to this record
 
 
Author Hinarejos, M.; Perez, A.; Roldan, E.; Romanelli, A.; de Valcarcel, G.J. url  doi
openurl 
  Title Understanding and controlling N-dimensional quantum walks via dispersion relations: application to the two-dimensional and three-dimensional Grover walks-diabolical points and more Type Journal Article
  Year (down) 2013 Publication New Journal of Physics Abbreviated Journal New J. Phys.  
  Volume 15 Issue Pages 073041 - 31pp  
  Keywords  
  Abstract The discrete quantum walk in N dimensions is analyzed from the perspective of its dispersion relations. This allows understanding known properties, as well as designing new ones when spatially extended initial conditions are considered. This is done by deriving wave equations in the continuum, which are generically of the Schrodinger type, and allows devising interesting behavior, such as ballistic propagation without deformation, or the generation of almost flat probability distributions, which is corroborated numerically. There are however special points where the energy surfaces display intersections and, near them, the dynamics is entirely different. Applications to the two- and three-dimensional Grover walks are presented.  
  Address [Hinarejos, Margarida; Perez, Armando] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: Armando.Perez@uv.es  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1367-2630 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000322110600003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1504  
Permanent link to this record
 
 
Author Perez, A.; Romanelli, A. url  doi
openurl 
  Title Spatially Dependent Decoherence and Anomalous Diffussion of Quantum Walks Type Journal Article
  Year (down) 2013 Publication Journal of Computational and Theoretical Nanoscience Abbreviated Journal J. Comput. Theor. Nanosci.  
  Volume 10 Issue 7 Pages 1591-1595  
  Keywords Decoherence; Quantum Walk; Non-Translational Invariance  
  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).  
  Address [Perez, A.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain  
  Corporate Author Thesis  
  Publisher Amer Scientific Publishers Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1546-1955 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000322605800007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1528  
Permanent link to this record
 
 
Author Hinarejos, M.; Bañuls, M.C.; Perez, A. url  doi
openurl 
  Title A Study of Wigner Functions for Discrete-Time Quantum Walks Type Journal Article
  Year (down) 2013 Publication Journal of Computational and Theoretical Nanoscience Abbreviated Journal J. Comput. Theor. Nanosci.  
  Volume 10 Issue 7 Pages 1626-1633  
  Keywords Quantum Walk; Wigner Function; Negativity  
  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.  
  Address [Hinarejos, M.; Perez, A.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain  
  Corporate Author Thesis  
  Publisher Amer Scientific Publishers Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1546-1955 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000322605800014 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1529  
Permanent link to this record
 
 
Author Bernal, A.; Perez, A. url  doi
openurl 
  Title Analytic behavior of the QED polarizability function at finite temperature Type Journal Article
  Year (down) 2012 Publication AIP Advances Abbreviated Journal AIP Adv.  
  Volume 2 Issue 1 Pages 012152 - 9pp  
  Keywords  
  Abstract We revisit the analytical properties of the static quasi-photon polarizability function for an electron gas at finite temperature, in connection with the existence of Friedel oscillations in the potential created by an impurity. In contrast with the zero temperature case, where the polarizability is an analytical function, except for the two branch cuts which are responsible for Friedel oscillations, at finite temperature the corresponding function is non analytical, in spite of becoming continuous everywhere on the complex plane. This effect produces, as a result, the survival of the oscillatory behavior of the potential. We calculate the potential at large distances, and relate the calculation to the non-analytical properties of the polarizability.  
  Address [Bernal, A.] Univ Barcelona, Dept Matemat Aplicada & Anal, E-08028 Barcelona, Spain  
  Corporate Author Thesis  
  Publisher Amer Inst Physics Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2158-3226 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000302225400070 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 983  
Permanent link to this record
 
 
Author Hinarejos, M.; Perez, A.; Bañuls, M.C. url  doi
openurl 
  Title Wigner function for a particle in an infinite lattice Type Journal Article
  Year (down) 2012 Publication New Journal of Physics Abbreviated Journal New J. Phys.  
  Volume 14 Issue Pages 103009 - 19pp  
  Keywords  
  Abstract We study the Wigner function for a quantum system with a discrete, infinite-dimensional Hilbert space, such as a spinless particle moving on a one-dimensional infinite lattice. We discuss the peculiarities of this scenario and of the associated phase-space construction, propose a meaningful definition of the Wigner function in this case and characterize the set of pure states for which it is non-negative. We propose a measure of non-classicality for states in this system, which is consistent with the continuum limit. The prescriptions introduced here are illustrated by applying them to localized and Gaussian states and to their superpositions.  
  Address [Banuls, M. C.] Max Planck Inst Quantum Opt, D-85748 Garching, Germany, Email: mari.banuls@mpq.mpg.de  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1367-2630 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000309396700001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1180  
Permanent link to this record
 
 
Author de Vega, I.; Bañuls, M.C.; Perez, A. url  doi
openurl 
  Title Effects of dissipation on an adiabatic quantum search algorithm Type Journal Article
  Year (down) 2010 Publication New Journal of Physics Abbreviated Journal New J. Phys.  
  Volume 12 Issue Pages 123010 - 19pp  
  Keywords  
  Abstract According to recent studies (Amin et al 2008 Phys. Rev. Lett. 100 060503), the effect of a thermal bath may improve the performance of a quantum adiabatic search algorithm. In this paper, we compare the effects of such a thermal environment on the algorithm performance with those of a structured environment similar to the one encountered in systems coupled to an electromagnetic field that exists within a photonic crystal. Whereas for all the parameter regimes explored here, the algorithm performance is worsened by contact with a thermal environment, the picture appears to be different when one considers a structured environment. In this case we show that by tuning the environment parameters to certain regimes, the algorithm performance can actually be improved with respect to the closed system case. Additionally, the relevance of considering the dissipation rates as complex quantities is discussed in both cases. More specifically, we find that the imaginary part of the rates cannot be neglected with the usual argument that it simply amounts to an energy shift and in fact influences crucially the system dynamics.  
  Address [de Vega, Ines] Univ Ulm, Inst Theoret Phys, D-89069 Ulm, Germany, Email: ines.devega@uni-ulm.de  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1367-2630 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000285582800002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 303  
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