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Author |
Gomis, P.; Perez, A. |
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Title |
Decoherence effects in the Stern-Gerlach experiment using matrix Wigner functions |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review A |
Abbreviated Journal |
Phys. Rev. A |
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Volume |
94 |
Issue |
1 |
Pages |
012103 - 11pp |
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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. |
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Address |
[Gomis, P.] Univ Valencia, CSIC, Dept Fis Teor, Dr Moliner 50, E-46100 Burjassot, Spain, Email: Pablo.Gomis@uv.es; |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
2469-9926 |
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Notes |
WOS:000378909000003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
2739 |
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Permanent link to this record |
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Author |
Bru, L.A.; de Valcarcel, G.J.; Di Molfetta, G.; Perez, A.; Roldan, E.; Silva, F. |
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Title |
Quantum walk on a cylinder |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review A |
Abbreviated Journal |
Phys. Rev. A |
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Volume |
94 |
Issue |
3 |
Pages |
032328 - 7pp |
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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. |
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Address |
[Bru, Luis A.] Univ Politecn Valencia, ITEAM Res Inst, Opt & Quantum Commun Grp, Camino Vera S-N, E-46022 Valencia, Spain |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
2469-9926 |
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Notes |
WOS:000384060700005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2823 |
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Author |
Hinarejos, M.; Bañuls, M.C.; Perez, A.; de Vega, I. |
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Title |
Non-Markovianity and memory of the initial state |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Physics A |
Abbreviated Journal |
J. Phys. A |
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Volume |
50 |
Issue |
32 |
Pages |
335301 - 17pp |
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Keywords |
non-Markovianity; quantum distinguisability; quantum fidelity |
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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. |
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Address |
[Hinarejos, Margarida] Univ Republica, Fac Ingn, Inst Fis, Av Julio Herrera y Reissig 565, Montevideo 11300, Uruguay, Email: Armando.Perez@uv.es |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
1751-8113 |
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Expedition |
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Conference |
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Notes |
WOS:000405672800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3206 |
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Permanent link to this record |
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Author |
Kim, J.S.; Lopez-Fogliani, D.E.; Perez, A.D.; Ruiz de Austri, R. |
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Title |
Right-handed sneutrino and gravitino multicomponent dark matter in light of neutrino detectors |
Type |
Journal Article |
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Year |
2023 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
04 |
Issue |
4 |
Pages |
050 - 32pp |
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Keywords |
dark matter theory; dark matter experiments; neutrino detectors |
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Abstract |
We investigate the possibility that right-handed (RH) sneutrinos and gravitinos can coexist and explain the dark matter (DM) problem. We compare extensions of the minimal supersymmetric standard model (MSSM) and the next-to-MSSM (NMSSM) adding RH neutrinos superfields, with special emphasis on the latter. If the gravitino is the lightest supersymmetric particle (LSP) and the RH sneutrino the next-to-LSP (NLSP), the heavier particle decays to the former plus left-handed (LH) neutrinos through the mixing between the scalar partners of the LH and RH neutrinos. However, the interaction is suppressed by the Planck mass, and if the LH-RH sneutrino mixing parameter is small, << O(10-2), a long-lived RH sneutrino NLSP is possible even surpassing the age of the Universe. As a byproduct, the NLSP to LSP decay produces monochromatic neutrinos in the ballpark of current and planned neutrino telescopes like Super-Kamiokande, IceCube and Antares that we use to set constraints and show prospects of detection. In the NMSSM+RHN, assuming a gluino mass parameter M3 = 3 TeV we found the following lower limits for the gravitino mass m3/2 >= 1-600 GeV and the reheating temperature TR >= 105-3 x 107 GeV, for m nu similar to R similar to 10-800 GeV. If we take M3 = 10 TeV, then the limits on TR are relaxed by one order of magnitude. |
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Address |
[Kim, Jong Soo] Univ Witwatersrand, Sch Phys, Johannesburg, South Africa, Email: jongsoo.kim@tu-dortmund.de; |
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Publisher |
IOP Publishing Ltd |
Place of Publication |
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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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ISSN |
1475-7516 |
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Notes |
WOS:000975382300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5523 |
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Permanent link to this record |
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Author |
Angles-Castillo, A.; Perez, A. |
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Title |
A quantum walk simulation of extra dimensions with warped geometry |
Type |
Journal Article |
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Year |
2022 |
Publication |
Scientific Reports |
Abbreviated Journal |
Sci Rep |
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Volume |
12 |
Issue |
1 |
Pages |
1926 - 12pp |
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Keywords |
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Abstract |
We investigate the properties of a quantum walk which can simulate the behavior of a spin 1/2 particle in a model with an ordinary spatial dimension, and one extra dimension with warped geometry between two branes. Such a setup constitutes a 1+ 1 dimensional version of the Randall-Sundrum model, which plays an important role in high energy physics. In the continuum spacetime limit, the quantum walk reproduces the Dirac equation corresponding to the model, which allows to anticipate some of the properties that can be reproduced by the quantum walk. In particular, we observe that the probability distribution becomes, at large time steps, concentrated near the “low energy” brane, and can be approximated as the lowest eigenstate of the continuum Hamiltonian that is compatible with the symmetries of the model. In this way, we obtain a localization effect whose strength is controlled by a warp coefficient. In other words, here localization arises from the geometry of the model, at variance with the usual effect that is originated from random irregularities, as in Anderson localization. In summary, we establish an interesting correspondence between a high energy physics model and localization in quantum walks. |
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Address |
[Angles-Castillo, Andreu] Univ Valencia, CSIC, Dept Fis Teor, Valencia 46100, Spain, Email: andreu.angles@ific.uv.es |
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Publisher |
Nature Portfolio |
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English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Edition |
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ISSN |
2045-2322 |
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Conference |
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Notes |
WOS:000751472600024 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5107 |
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Permanent link to this record |
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Author |
Hinarejos, M.; Di Franco, C.; Romanelli, A.; Perez, A. |
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Title |
Chirality asymptotic behavior and non-Markovianity in quantum walks on a line |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review A |
Abbreviated Journal |
Phys. Rev. A |
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Volume |
89 |
Issue |
5 |
Pages |
052330 - 7pp |
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Keywords |
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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. |
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Address |
[Hinarejos, Margarida; Perez, Armando] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain |
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Publisher |
Amer Physical Soc |
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English |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1050-2947 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000336751300003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1807 |
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Permanent link to this record |
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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 |
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English |
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Series Issue |
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Edition |
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ISSN |
1546-1955 |
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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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Permanent link to this record |
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Author |
Angles-Castillo, A.; Perez, A.; Roldan, E. |
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Title |
Bright and dark solitons in a photonic nonlinear quantum walk: lessons from the continuum |
Type |
Journal Article |
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Year |
2024 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
26 |
Issue |
2 |
Pages |
023004 - 16pp |
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Keywords |
quantum walks; soliton; non-linear optics |
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Abstract |
We propose a nonlinear quantum walk model inspired in a photonic implementation in which the polarization state of the light field plays the role of the coin-qubit. In particular, we take profit of the nonlinear polarization rotation occurring in optical media with Kerr nonlinearity, which allows to implement a nonlinear coin operator, one that depends on the state of the coin-qubit. We consider the space-time continuum limit of the evolution equation, which takes the form of a nonlinear Dirac equation. The analysis of this continuum limit allows us to gain some insight into the existence of different solitonic structures, such as bright and dark solitons. We illustrate several properties of these solitons with numerical calculations, including the effect on them of an additional phase simulating an external electric field. |
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Address |
[Angles-Castillo, Andreu; Perez, Armando] Univ Valencia, Dept Fis Teor & IFIC, CSIC, Burjassot 46100, Valencia, Spain, Email: andreu.angles-castillo@uv.es |
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Publisher |
IOP Publishing Ltd |
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English |
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Edition |
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ISSN |
1367-2630 |
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Expedition |
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Conference |
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Notes |
WOS:001156767400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5929 |
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Permanent link to this record |
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Author |
Bernal, A.; Perez, A. |
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Title |
Analytic behavior of the QED polarizability function at finite temperature |
Type |
Journal Article |
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Year |
2012 |
Publication |
AIP Advances |
Abbreviated Journal |
AIP Adv. |
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Volume |
2 |
Issue |
1 |
Pages |
012152 - 9pp |
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Keywords |
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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. |
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Address |
[Bernal, A.] Univ Barcelona, Dept Matemat Aplicada & Anal, E-08028 Barcelona, Spain |
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Publisher |
Amer Inst Physics |
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English |
Summary Language |
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ISSN |
2158-3226 |
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Notes |
WOS:000302225400070 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
983 |
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Permanent link to this record |
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Author |
Perez, A. |
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Title |
Asymptotic properties of the Dirac quantum cellular automaton |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review A |
Abbreviated Journal |
Phys. Rev. A |
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Volume |
93 |
Issue |
1 |
Pages |
012328 - 10pp |
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Keywords |
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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. |
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Address |
[Perez, A.] Univ Valencia, CSIC, IFIC, Dept Fis Teor, E-46100 Valencia, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Series Editor |
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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 |
1050-2947 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000368291600005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
2520 |
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Permanent link to this record |