Center for Theoretical Physics

About: Center for Theoretical Physics is a facility organization based out in Warsaw, Poland. It is known for research contribution in the topics: Gamma-ray burst & Accretion (astrophysics). The organization has 68 authors who have published 112 publications receiving 1086 citations. The organization is also known as: Centrum Fizyki Teoretycznej PAN & Centrum Fizyki Teoretycznej Polskiej Akademii Nauk.

Effect of one-, two-, and three-body atom loss processes on superpositions of phase states in Bose-Josephson junctions

Abstract: In a two-mode Bose-Josephson junction formed by a binary mixture of ultracold atoms, macroscopic superpositions of phase states are produced during the time evolution after a sudden quench to zero of the coupling amplitude. Using quantum trajectories and an exact diagonalization of the master equation, we study the effect of one-, two-, and three-body atom losses on the superpositions by analyzing separately the amount of quantum correlations in each subspace with fixed atom number. The quantum correlations useful for atom interferometry are estimated using the quantum Fisher information. We identify the choice of parameters leading to the largest Fisher information, thereby showing that, for all kinds of loss processes, quantum correlations can be partially protected from decoherence when the losses are strongly asymmetric in the two modes.

Twisted localized solutions of the Dirac equation: Hopfionlike states of relativistic electrons

Abstract: All known solutions of the Dirac equation describing states of electrons endowed with angular momentum are very far from our notion of the electron as a spinning charged bullet because they are not localized in the direction of propagation. We present here analytic exact solutions, eigenstates of the total angular momentum component $M_z$, that come very close to this notion. These new solutions of the Dirac equation have also intricate topological properties similar to the hopfion solutions of the Maxwell equations.

Non-signaling boxes and quantum logics

Abstract: Using a quantum logic approach we analyze the structure of the so-called non-signaling theories respecting relativistic causality, but allowing correlations violating bounds imposed by quantum mechanics such as CHSH inequality We discuss the relations among such theories, quantum mechanics, and classical physics Our main result is the construction of a probability theory adequate for the simplest instance of a non-signaling theory—the two non-signaling boxes world—in which we exhibit its differences in comparison with classical and quantum probabilities We show that the question of whether such a theory can be treated as a kind of 'generalization' of the quantum theory of the two-qubit system cannot be answered positively Some of its features put it closer to the quantum world—on the one hand, for example, the measurements are destructive, though on the other hand the Heisenberg uncertainty relations are not satisfied Another interesting property contrasting it from quantum mechanics is that the subset of 'classically correlated states', ie the states with only classical correlations, does not reproduce the classical world of the two two-state systems Our results establish a new link between quantum information theory and the well-developed theory of quantum logics

Stellar populations in hosts of giant radio galaxies and their neighbouring galaxies

Abstract: Context: Giant radio galaxies (with projected linear size of radio structure larger than 0.7 Mpc) are very rare and unusual objects. Only $\sim$5% of extended radio sources reach such sizes. Understanding of the processes responsible for their large sizes is crucial to further our knowledge about the radio source's evolution. Aims: We check the hypothesis that giants become extremely large due to the specific history of their host galaxy formation, as well as in the context of the cluster or group of galaxies where they evolve. Therefore we study the star formation histories in their host galaxies and in galaxies located in their neighbourhood. Methods: We studied 41 giant-size radio galaxies as well as galaxies located within a radius of 5 Mpc around giants to verify whether the external conditions of the intergalactic medium somehow influence the internal evolution of galaxies in the group/cluster. We compared the results with a control sample of smaller-sized Fanaroff--Riley type II radio galaxies and their neighbouring galaxies. We fit stellar continua in all galaxy spectra using the spectral synthesis code STARLIGHT and provide statistical analysis of the results. Results: We find that hosts of giant radio galaxies have a larger amount of intermediate age stellar populations compared with smaller-sized FRII radio sources. The same result is also visible when we compare neighbouring galaxies located up to 1.5 Mpc around giants and FRIIs. This may be evidence that star formation in groups with giants was triggered due to global processes occurring in the ambient intergalactic medium. These processes may also contribute to mechanisms responsible for the extremely large sizes of giants.

The MRI Imprint on the Short-GRB Jets

Abstract: Short gamma ray bursts are presumably results of binary neutron star mergers, which lead to the formation of a stellar mass black hole, surrounded by a remnant matter. The strong magnetic fields help collimate jets of plasma, launched along the axis of the black hole rotation. We study the structure and evolution of the accreting plasma in the short GRBs and we model the formation of the base of a relativistic, Poynting-dominated jets. Our numerical models are based on the general relativistic MHD, axisymmetric simulations. We discuss the origin of variability in the GRB jet emission, which timescales are related to the action of the magneto-rotational instability in the accreting plasma. We also estimate the value of a maximum achievable Lorentz factor in the jets produced by our simulations, and reached at the large distances, where the gamma ray emission is produced.