34 research outputs found
Propagation and spectral properties of quantum walks in electric fields
We study one-dimensional quantum walks in a homogeneous electric field. The
field is given by a phase which depends linearly on position and is applied
after each step. The long time propagation properties of this system, such as
revivals, ballistic expansion and Anderson localization, depend very
sensitively on the value of the electric field , e.g., on whether
is rational or irrational. We relate these properties to the
continued fraction expansion of the field. When the field is given only with
finite accuracy, the beginning of the expansion allows analogous conclusions
about the behavior on finite time scales.Comment: 7 pages, 4 figure
Propagation of Quantum Walks in Electric Fields
We study one-dimensional quantum walks in a homogenous electric field. The field is given by a phase which depends linearly on position and is applied after each step. The long time propagation properties of this system, such as revivals, ballistic expansion, and Anderson localization, depend very sensitively on the value of the electric field, Φ, e.g., on whether Φ/(2π) is rational or irrational. We relate these properties to the continued fraction expansion of the field. When the field is given only with finite accuracy, the beginning of the expansion allows analogous conclusions about the behavior on finite time scales
Simulation of indivisible qubit channels in collision models
A sequence of controlled collisions between a quantum system and its
environment (composed of a set of quantum objects) naturally simulates (with
arbitrary precision) any Markovian quantum dynamics of the system under
consideration. In this paper we propose and study the problem of simulation of
an {\it arbitrary} quantum channel via collision models. We show that a
correlated environment is capable to simulate {\it non-Markovian} evolutions
leading to any indivisible qubit channel. In particular, we derive the
corresponding master equation generating a continuous time non-Markovian
dynamics implementing the universal NOT gate being an example of the most
non-Markovian quantum channels.Comment: 6 pages, 2 figures, submitted to JP
7-Substituierte 8-Vinyl-1,3-dimethyl-3,7-dihydro-1H-purin-2,6-dione und ihre broncholytische Wirkung
40Ar/Ar30 geochronology of Burdigalian paleobotanical localities in the central Paratethys (south Slovakia)
The Lipovany and Mučín paleobotanical localities contain important floral associations within the tuff horizons, which were used for determination of subtropical to tropical climatic conditions during Early Miocene. Based on the combination of results from plagioclase and biotite 40Ar/39Ar dating, the age of the tuff deposition was around 17.3 Ma. From the Lipovany locality, the plagioclase convergent age is 17.49 ± 0.54 Ma. Biotite convergent age is 17.28 ± 0.06 Ma. The Mučín locality only provide a imprecise convergent age of 16.5 ± 1.4 Ma due to the small size of the plagioclase crystals analyzed. The results thus allowed to include the fossil subtropical flora of the studied localities to the late Ottnangian stage (upper part of the Burdigalian stage). Additionally, they also indicate late Ottnangian-Karpatian deposition age of the Salgótarján Formatio