Wydział Fizyki i Informatyki Stosowanej/Faculty of Physics and Applied Informatics
http://hdl.handle.net/11089/6
2021-10-18T03:46:05ZLorentz-covariant, unitary evolution of a relativistic Majorana qubit
http://hdl.handle.net/11089/39359
Lorentz-covariant, unitary evolution of a relativistic Majorana qubit
Smoliński, Kordian; Rembieliński, Jakub; Caban, Paweł; Khrapko, Sviatoslav
We formulate a covariant description of a relativistic qubit identified with an irreducible set of quantum spin states of a Majorana particle with a sharp momentum. We treat the particle’s four-momentum as an external parameter. We show that it is possible to define an interesting time evolution of the spin density matrix of such a qubit. This evolution is manifestly Lorentz covariant in the bispinor representation and unitary in the spin representation. Moreover, during this evolution the Majorana particle undergoes an uniformly accelerated motion. We classify possible types of such motions, and finally we illustrate the behaviour of the polarization vector of the Majorana qubit during the evolution in some special cases.
2018-01-01T00:00:00ZAn analysis method for data taken by Imaging Air Cherenkov Telescopes at very high energies under the presence of clouds
http://hdl.handle.net/11089/39353
An analysis method for data taken by Imaging Air Cherenkov Telescopes at very high energies under the presence of clouds
Sobczyńska, Dorota; Adamczyk, Katarzyna; Sitarek, Julian; Szanecki, Michał
The effective observation time of Imaging Air Cherenkov Telescopes (IACTs) plays an important role in the detection of γ-ray sources, especially when the expected flux is low. This time is strongly limited by the atmospheric conditions. Significant extinction of Cherenkov light caused by the presence of clouds reduces the photon detection rate and also complicates or even makes impossible proper data analysis. However, for clouds with relatively high atmospheric transmission, high energy showers can still produce enough Cherenkov photons to allow their detection by IACTs. In this paper, we study the degradation of the detection capability of an array of small-sized telescopes for different cloud transmissions. We show the expected changes of the energy bias, energy and angular resolution and the effective collection area caused by absorption layers located at 2.5 and 4.5 km above the observation level. We demonstrate simple correction methods for reconstructed energy and effective collection area. As a result, the source flux that is observed during the presence of clouds is determined with a systematic error of 20%. Finally, we show that the proposed correction method can be used for clouds at altitudes higher than 5 km a.s.l. As a result, the analysis of data taken under certain cloudy conditions will not require additional time- consuming Monte Carlo simulations.
2020-01-01T00:00:00ZAn Extremum Principle for Smooth Problems
http://hdl.handle.net/11089/39350
An Extremum Principle for Smooth Problems
Idczak, Dariusz; Walczak, Stanislaw
We derive an extremum principle. It can be treated as an intermediate result between
the celebrated smooth-convex extremum principle due to Ioffe and Tikhomirov and the
Dubovitskii–Milyutin theorem. The proof of this principle is based on a simple generalization of the
Fermat’s theorem, the smooth-convex extremum principle and the local implicit function theorem.
An integro-differential example illustrating the new principle is presented.
2020-01-01T00:00:00ZThe covariance of chiral fermions theory
http://hdl.handle.net/11089/39245
The covariance of chiral fermions theory
Gonera, Cezary; Maślanka, Paweł; Andrzejewski, Krzysztof; Gonera, Joanna; Kosinski, Piotr; Brihaye, Yves
The quasiclassical theory of massless chiral fermions is considered. The effective action is derived using time-dependent variational principle which provides a clear interpretation of relevant canonical variables. As a result their transformation properties under the action of Lorentz group are derived from first principles.
2019-01-01T00:00:00Z