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Author (up) Angles-Castillo, A.; Bañuls, M.C.; Perez, A.; De Vega, I. url  doi
openurl 
  Title Prethermalization of quantum systems interacting with non-equilibrium environments Type Journal Article
  Year 2020 Publication New Journal of Physics Abbreviated Journal New J. Phys.  
  Volume 22 Issue 8 Pages 083067 - 17pp  
  Keywords open quantum systems; prethermalization; master equations  
  Abstract The usual paradigm of open quantum systems falls short when the environment is actually coupled to additional fields or components that drive it out of equilibrium. Here we explore the simplest such scenario, by considering a two level system coupled to a first thermal reservoir that in turn couples to a second thermal bath at a different temperature. We derive a master equation description for the system and show that, in this situation, the dynamics can be especially rich. In particular, we observe prethermalization, a transitory phenomenon in which the system initially approaches thermal equilibrium with respect to the first reservoir, but after a longer time converges to the thermal state dictated by the temperature of the second environment. Using analytical arguments and numerical simulations, we analyze the occurrence of this phenomenon, and how it depends on temperatures and coupling strengths. The phenomenology gets even richer if the system is placed between two such non-equilibrium environments. In this case, the energy current through the system may exhibit transient features and even switch direction, before the system eventually reaches a non-equilibrium steady state.  
  Address [Angles-Castillo, Andreu; Perez, Armando] Univ Valencia, CSIC, Dept Fis Teor, Burjassot 46100, Valencia, 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:000565705900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4525  
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Author (up) 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 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  
Permanent link to this record
 

 
Author (up) 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 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 (up) 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 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 (up) Hinarejos, M.; Bañuls, M.C.; Perez, A.; de Vega, I. url  doi
openurl 
  Title Non-Markovianity and memory of the initial state Type Journal Article
  Year 2017 Publication Journal of Physics A Abbreviated Journal J. Phys. A  
  Volume 50 Issue 32 Pages 335301 - 17pp  
  Keywords non-Markovianity; quantum distinguisability; quantum fidelity  
  Abstract We explore in a rigorous manner the intuitive connection between the non-Markovianity of the evolution of an open quantum system and the performance of the system as a quantum memory. Using the paradigmatic case of a two-level open quantum system coupled to a bosonic bath, we compute the recovery fidelity, which measures the best possible performance of the system to store a qubit of information. We deduce that this quantity is connected, but not uniquely determined, by the non-Markovianity, for which we adopt the Breuer-Laine-Piilo measure proposed in Breuer et al (2009 Phys. Rev. Lett. 103 210401). We illustrate our findings with explicit calculations for the case of a structured environment.  
  Address [Hinarejos, Margarida] Univ Republica, Fac Ingn, Inst Fis, Av Julio Herrera y Reissig 565, Montevideo 11300, Uruguay, 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 1751-8113 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000405672800001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3206  
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