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Author |
de Vega, I.; Bañuls, M.C.; Perez, A. |
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Title |
Effects of dissipation on an adiabatic quantum search algorithm |
Type |
Journal Article |
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Year |
2010 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
12 |
Issue  |
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Pages |
123010 - 19pp |
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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. |
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Address |
[de Vega, Ines] Univ Ulm, Inst Theoret Phys, D-89069 Ulm, Germany, Email: ines.devega@uni-ulm.de |
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Iop Publishing Ltd |
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English |
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ISSN |
1367-2630 |
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Notes |
ISI:000285582800002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
303 |
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Author |
Hinarejos, M.; Perez, A.; Bañuls, M.C. |
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Title |
Wigner function for a particle in an infinite lattice |
Type |
Journal Article |
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Year |
2012 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
14 |
Issue |
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Pages |
103009 - 19pp |
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Keywords |
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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. |
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Address |
[Banuls, M. C.] Max Planck Inst Quantum Opt, D-85748 Garching, Germany, Email: mari.banuls@mpq.mpg.de |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
1367-2630 |
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Conference |
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Notes |
WOS:000309396700001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1180 |
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Author |
Hinarejos, M.; Perez, A.; Roldan, E.; Romanelli, A.; de Valcarcel, G.J. |
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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 |
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Year |
2013 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
15 |
Issue |
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Pages |
073041 - 31pp |
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Keywords |
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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. |
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Address |
[Hinarejos, Margarida; Perez, Armando] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: Armando.Perez@uv.es |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
1367-2630 |
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Expedition |
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Conference |
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Notes |
WOS:000322110600003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1504 |
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Author |
Hinarejos, M.; Bañuls, M.C.; Perez, A. |
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Title |
Wigner formalism for a particle on an infinite lattice: dynamics and spin |
Type |
Journal Article |
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Year |
2015 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
17 |
Issue |
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Pages |
013037 - 16pp |
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Keywords |
Wigner functions; dynamics on a lattice; spin-dependent forces |
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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. |
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Address |
[Hinarejos, M.; Perez, A.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: banulsm@mpq.mpg.de |
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Publisher |
Iop Publishing Ltd |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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ISSN |
1367-2630 |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000348759800007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2101 |
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Author |
Di Molfetta, G.; Perez, A. |
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Title |
Quantum walks as simulators of neutrino oscillations in a vacuum and matter |
Type |
Journal Article |
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Year |
2016 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
18 |
Issue |
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Pages |
103038 - 8pp |
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Keywords |
quantum walks; neutrino oscillations; quantum simulation |
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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. |
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Address |
[Di Molfetta, G.] Univ Valencia, CSIC, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: giuseppe.dimolfetta@lif.univ-mrs.fr |
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Corporate Author |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1367-2630 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000386816100004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2846 |
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