Mol. Phys. Rep. Suppl. 1(New Trends in Atomic Physics,Wolfgang Paul Colloquium in memoriam of Wolfgang Paul), 46 (2001)
M. Gajda, Z. Idziaszek, K. Rzążewski, and P. Navez
Jan 19, 2001
Multi-mode description of an interacting Bose-Einstein condensate
Opt. Express 8, 92 (2001)
Krzysztof Goral, Mariusz Gajda, and Kazimierz Rzazewski
We study the equilibrium dynamics of a weakly interacting Bose-Einstein condensate trapped in a box. In our approach we use a semiclassical approximation similar to the description of a multi-mode laser. In dynamical equations derived from a full N-body quantum Hamiltonian we substitute all creation (and annihilation) operators (of a particle in a given box state) by appropriate c-number amplitudes. The set of nonlinear equations obtained in this way is solved numerically. We show that on the time scale of a few miliseconds the system exhibits relaxation -- reaches an equilibrium with populations of different eigenstates fluctuating around their mean values.
Krzysztof Goral, Mariusz Gajda, and Kazimierz Rzazewski
We study the equilibrium dynamics of a weakly interacting Bose-Einstein condensate trapped in a box. In our approach we use a semiclassical approximation similar to the description of a multi-mode laser. In dynamical equations derived from a full N-body quantum Hamiltonian we substitute all creation (and annihilation) operators (of a particle in a given box state) by appropriate c-number amplitudes. The set of nonlinear equations obtained in this way is solved numerically. We show that on the time scale of a few miliseconds the system exhibits relaxation -- reaches an equilibrium with populations of different eigenstates fluctuating around their mean values.
Jan 10, 2001
Ionization of hydrogen atoms by intense vacuum ultraviolet radiation
J. Phys. B 34, 2245 (2001)
Jaroslaw Bauer, Lukasz Plucinski, Bernard Piraux, Robert Potvliege, Mariusz Gajda and Jacek Krzywinski
We study the ionization of hydrogen atoms by an intense pulsed beam of photons with energies of 17 or 50 eV. The work is motivated by the demonstration of the free-electron laser (FEL) action at the DESY Laboratory. The parameters chosen for the incident field are in the regime accessible by the FEL. Ionization yields are obtained within three different approaches, namely the strong-field approximation, the Floquet method and a numerical solution of the time-dependent Schrödinger equation. A marked stabilization effect for 50 eV photons is shown.
Jaroslaw Bauer, Lukasz Plucinski, Bernard Piraux, Robert Potvliege, Mariusz Gajda and Jacek Krzywinski
We study the ionization of hydrogen atoms by an intense pulsed beam of photons with energies of 17 or 50 eV. The work is motivated by the demonstration of the free-electron laser (FEL) action at the DESY Laboratory. The parameters chosen for the incident field are in the regime accessible by the FEL. Ionization yields are obtained within three different approaches, namely the strong-field approximation, the Floquet method and a numerical solution of the time-dependent Schrödinger equation. A marked stabilization effect for 50 eV photons is shown.
Nov 9, 2000
On coherence of Bose fields
Mariusz Gajda, Magdalena Zaluska-Kotur, and Jan Mostowski
We study a system of interacting bosons at zero temperature in an atomic trap. Using wave function that models the ground state of interacting bosons we examine the concepts of the order parameter, off-diagonal order and coherence of the system. We suggest that the coherence length becomes much smaller than the size of the system if the number of trapped particles exceeds a certain limit. This behavior is related to the unavoidable existence of two different length scales -- one determined by the external potential and the second one depending on the two-body forces.
Opt. Express 8, 106 (2001)
We study a system of interacting bosons at zero temperature in an atomic trap. Using wave function that models the ground state of interacting bosons we examine the concepts of the order parameter, off-diagonal order and coherence of the system. We suggest that the coherence length becomes much smaller than the size of the system if the number of trapped particles exceeds a certain limit. This behavior is related to the unavoidable existence of two different length scales -- one determined by the external potential and the second one depending on the two-body forces.
Opt. Express 8, 106 (2001)
Oct 5, 2000
Correlations in financial time series: established versus emerging markets
Eur. Phys. J. B 20, 527 (2001)
M. Beben and A. Orłowski
Long-time correlations in both well-developed and emerging market indexes are studied. The Hurst exponent as well as detrended fluctuations analysis (DFA) are used as technical tools. Some features that seem to be specific for developing markets are discovered and briefly discussed.
M. Beben and A. Orłowski
Long-time correlations in both well-developed and emerging market indexes are studied. The Hurst exponent as well as detrended fluctuations analysis (DFA) are used as technical tools. Some features that seem to be specific for developing markets are discovered and briefly discussed.
Jul 12, 2000
Squeezing of electromagnetic field in a cavity by electrons in Trojan states
Piotr Kochański, Zofia Bialynicka-Birula, and Iwo Bialynicki-Birula
The notion of the Trojan state of a Rydberg electron, introduced by I. Bialynicki-Birula, M. Kaliński, and J. H. Eberly [Phys. Rev. Lett. 73, 1777 (1994)] is extended to the case of an electromagnetic field quantized in a cavity. The shape of the electronic wave packet describing the Trojan state is practically the same as in the previously studied externally driven system. The fluctuations of the quantized electromagnetic field around its classical value exhibit strong squeezing. The emergence of Trojan states in the cylindrically symmetrical system is attributed to spontaneous symmetry breaking.
Phys. Rev. A 63, 013811 (2001)
The notion of the Trojan state of a Rydberg electron, introduced by I. Bialynicki-Birula, M. Kaliński, and J. H. Eberly [Phys. Rev. Lett. 73, 1777 (1994)] is extended to the case of an electromagnetic field quantized in a cavity. The shape of the electronic wave packet describing the Trojan state is practically the same as in the previously studied externally driven system. The fluctuations of the quantized electromagnetic field around its classical value exhibit strong squeezing. The emergence of Trojan states in the cylindrically symmetrical system is attributed to spontaneous symmetry breaking.
Phys. Rev. A 63, 013811 (2001)
Jun 10, 2000
May 30, 2000
Multimode Dynamics of a Coupled Ultracold Atomic-Molecular System
Phys. Rev. Lett. 86, 1397 (2001)
Krzysztof Góral, Mariusz Gajda, and Kazimierz Rzążewski
We analyze the coherent multimode dynamics of a system of coupled atomic and molecular Bose gases. Starting from an atomic Bose-Einstein condensate with a small thermal component, we observe a complete depletion of the atomic and molecular condensate modes on a short time scale due to a significant population of excited states. Giant coherent oscillations between the two condensates for typical parameters are almost completely suppressed. Our results cast serious doubts on the common use of the 2-mode model for the description of coupled ultracold atomic-molecular systems and should be considered when planning future experiments with ultracold molecules.
Krzysztof Góral, Mariusz Gajda, and Kazimierz Rzążewski
We analyze the coherent multimode dynamics of a system of coupled atomic and molecular Bose gases. Starting from an atomic Bose-Einstein condensate with a small thermal component, we observe a complete depletion of the atomic and molecular condensate modes on a short time scale due to a significant population of excited states. Giant coherent oscillations between the two condensates for typical parameters are almost completely suppressed. Our results cast serious doubts on the common use of the 2-mode model for the description of coupled ultracold atomic-molecular systems and should be considered when planning future experiments with ultracold molecules.
May 26, 2000
Cluster explosion in an intense laser pulse: Thomas-Fermi model
Physical Review A 63, 013203 (2001)
Marian Rusek, Herve Lagadec and Thomas Blenski
A refined three-dimensional version of the time-dependent Thomas-Fermi model is used to qualitatively study the explosion of rare-gas atomic clusters in an intense laser field. Clusters as large as 55 atoms are exposed to a strong subpicosecond laser pulse. A stepwise character of the explosion is observed in which atomic shells are expelled sequentially. The role of “hot” electron dynamics in the explosion process is also investigated via initial temperature effects. Contrary to previous opinions it seems that the so-called hydrodynamic explosion scenario is important for most energetic ions coming from the outermost shells only.
Marian Rusek, Herve Lagadec and Thomas Blenski
A refined three-dimensional version of the time-dependent Thomas-Fermi model is used to qualitatively study the explosion of rare-gas atomic clusters in an intense laser field. Clusters as large as 55 atoms are exposed to a strong subpicosecond laser pulse. A stepwise character of the explosion is observed in which atomic shells are expelled sequentially. The role of “hot” electron dynamics in the explosion process is also investigated via initial temperature effects. Contrary to previous opinions it seems that the so-called hydrodynamic explosion scenario is important for most energetic ions coming from the outermost shells only.
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