Laarmann T, Rusek M, Wabnitz H, Schulz J, de Castro AR, Gürtler P, Laasch W, Möller T
The ionization dynamics of Ar and Xe clusters irradiated with intense vacuum ultraviolet light from a free-electron laser is investigated using photoelectron spectroscopy. Clusters comprising between 70 and 900 atoms were irradiated with femtosecond pulses at 95 nm wavelength (~13 eV photon energy) and a peak intensity of ~4×1012 W/cm2. A broad thermal distribution of emitted electrons from clusters with a maximum kinetic energy up to 30–40 eV is observed. The observation of relatively low-energy photoelectrons is in good agreement with calculations using a time-dependent Thomas-Fermi model and gives experimental evidence of an outer ionization process of the clusters, due to delayed thermoelectronic emission.
Phys Rev Lett. 2005 Aug 5;95(6):063402. Epub 2005 Aug 5
Aug 5, 2005
Jul 11, 2005
Phase fluctuations of a Bose-Einstein condensate in low-dimensional geometry
Demascoth Kadio, Mariusz Gajda and Kazimierz Rzążewski
We investigate the phase fluctuations of a Bose-Einstein condensate in one- (1D) and three-dimensional (3D) elongated harmonic traps with the help of the numerical simulation using classical field approximation. By calculating the eigenvalues of the one-dimensional single-particle density matrix we show that the phase fluctuations of a Bose-Einstein Condensate in a 1D system are due to the thermal low-energy excitations. We find that the phase fluctuations depend on the temperature as has been predicted [Phys. Rev. Lett. 85, 3745 (2000), Phys. Rev. Lett. 87, 050404 (2001)]. Finally we show that the phase coherence length of a condensate in a harmonic trap depends on the aspect ratio of anisotropy (geometry) of the trap. We determine the border between the 3D and quasi-one-dimensional systems by calculating the phase coherence length of the condensate.
Phys. Rev. A 72, 013607 (2005)
We investigate the phase fluctuations of a Bose-Einstein condensate in one- (1D) and three-dimensional (3D) elongated harmonic traps with the help of the numerical simulation using classical field approximation. By calculating the eigenvalues of the one-dimensional single-particle density matrix we show that the phase fluctuations of a Bose-Einstein Condensate in a 1D system are due to the thermal low-energy excitations. We find that the phase fluctuations depend on the temperature as has been predicted [Phys. Rev. Lett. 85, 3745 (2000), Phys. Rev. Lett. 87, 050404 (2001)]. Finally we show that the phase coherence length of a condensate in a harmonic trap depends on the aspect ratio of anisotropy (geometry) of the trap. We determine the border between the 3D and quasi-one-dimensional systems by calculating the phase coherence length of the condensate.
Phys. Rev. A 72, 013607 (2005)
Criterion for Bose-Einstein condesation in a harmonic trap in the case with attractive interactions
Mariusz Gajda
Using a model many-body wave function I analyze the standard criterion for Bose-Einstein condensation and its relation to coherence properties of the system. I pay special attention to an attractive condensate under such a condition that a characteristic length scale of the spatial extension of its center of mass differs significantly from length scales of relative coordinates. I show that although no interference fringes are produced in the two-slit Young interference experiment performed on this system, fringes of a high visibility can be observed in a conditional simultaneous detection of two particles.
Phys. Rev. A vol. 73, 023603 - 1-5 (2006) [1/1]
Using a model many-body wave function I analyze the standard criterion for Bose-Einstein condensation and its relation to coherence properties of the system. I pay special attention to an attractive condensate under such a condition that a characteristic length scale of the spatial extension of its center of mass differs significantly from length scales of relative coordinates. I show that although no interference fringes are produced in the two-slit Young interference experiment performed on this system, fringes of a high visibility can be observed in a conditional simultaneous detection of two particles.
Phys. Rev. A vol. 73, 023603 - 1-5 (2006) [1/1]
Jun 13, 2005
On the stability of Bose-Fermi mixtures
T Karpiuk, M Brewczyk, M Gajda and K Rzążewski
We consider the stability of a mixture of degenerate Bose and Fermi gases. Even though the bosons effectively repel each other, the mixture can still collapse provided the Bose and Fermi gases attract each other strongly enough. For a given number of atoms and the strengths of the interactions between them, we find the geometry of a maximally compact trap that supports the stable mixture. We compare a simple analytical estimation for the critical axial frequency of the trap with results based on the numerical solution of hydrodynamic equations for the Bose–Fermi mixture.
J. Phys. B: At. Mol. Opt. Phys. 38 L215-L221
We consider the stability of a mixture of degenerate Bose and Fermi gases. Even though the bosons effectively repel each other, the mixture can still collapse provided the Bose and Fermi gases attract each other strongly enough. For a given number of atoms and the strengths of the interactions between them, we find the geometry of a maximally compact trap that supports the stable mixture. We compare a simple analytical estimation for the critical axial frequency of the trap with results based on the numerical solution of hydrodynamic equations for the Bose–Fermi mixture.
J. Phys. B: At. Mol. Opt. Phys. 38 L215-L221
May 24, 2005
Semi-classical approaches to the ion-atom scattering
Maciej Janowicz, Katarzyna Słabkowska, Piotr Matuszak and Marek Polasik
Three semi-classical approaches to the simulation of ion–atom scattering: the Kirschbaum–Wilets, the Cohen energy-bounded, and the wave-packet – are used to calculate the ionization and charge-transfer cross sections for the scattering of fully stripped sulfur ions on atomic hydrogen. Their comparison in the high-energy regime is provided. Elements of microscopic analysis of Kirschbaum–Wilets trajectories are given.
Nuclear Instruments and Methods in Physics Research Section B Vol 235, 1-4, (2005)
Three semi-classical approaches to the simulation of ion–atom scattering: the Kirschbaum–Wilets, the Cohen energy-bounded, and the wave-packet – are used to calculate the ionization and charge-transfer cross sections for the scattering of fully stripped sulfur ions on atomic hydrogen. Their comparison in the high-energy regime is provided. Elements of microscopic analysis of Kirschbaum–Wilets trajectories are given.
Nuclear Instruments and Methods in Physics Research Section B Vol 235, 1-4, (2005)
Apr 14, 2005
Different mechanisms of cluster explosion within an unified time-dependent Thomas-Fermi approach: optical and short-wavelength regimes compared
Marian Rusek and Arkadiusz Orlowski
The dynamics of small (55 atoms) argon clusters ionized by an intense femtosecond laser pulse is studied using a time-dependent Thomas-Fermi model. The resulting Bloch-like hydrodynamic equations are solved numerically using the smooth particle hydrodynamics method without the necessity of grid simulations. As follows from recent experiments, absorption of radiation and subsequent ionization of clusters observed in the short-wavelength laser frequency regime (98 nm) differs considerably from that in the optical spectral range (800 nm). Our theoretical approach provides a unified framework for treating these very different frequency regimes and allows for a deeper understanding of the underlying cluster explosion mechanisms. The results of our analysis following from extensive numerical simulations presented in this paper are compared both with experimental findings and with predictions of other theoretical models.
Phys. Rev. A 71, 043202 (2005)
The dynamics of small (55 atoms) argon clusters ionized by an intense femtosecond laser pulse is studied using a time-dependent Thomas-Fermi model. The resulting Bloch-like hydrodynamic equations are solved numerically using the smooth particle hydrodynamics method without the necessity of grid simulations. As follows from recent experiments, absorption of radiation and subsequent ionization of clusters observed in the short-wavelength laser frequency regime (98 nm) differs considerably from that in the optical spectral range (800 nm). Our theoretical approach provides a unified framework for treating these very different frequency regimes and allows for a deeper understanding of the underlying cluster explosion mechanisms. The results of our analysis following from extensive numerical simulations presented in this paper are compared both with experimental findings and with predictions of other theoretical models.
Phys. Rev. A 71, 043202 (2005)
Feb 16, 2005
Trojan States of Electrons Guided by Bessel Beams
Iwo Bialynicki-Birula, Zofia Bialynicka-Birula and Bartosz Chmura
Previous work [I. Bialynicki-Birula, Phys. Rev. Lett. {\bf 93}, 20402 (2004)] is extended to cover more realistic examples of electromagnetic waves, viz. the Bessel beams. It is shown that electrons may be guided by a Bessel beam with nonvanishing orbital angular momentum. The mechanism for trapping the electrons near the electromagnetic vortex line of such a wave field is the same as for the Trojan states of Rydberg electrons produced by a circularly polarized wave. The main difference is that in the present case the transverse motion of electrons in a beam is confined under the action of the electromagnetic wave alone, no additional attraction center is required. We also discuss briefly the motion of electrons in Neumann and Hankel beams.
Physics/0502025 (February 2005)
Previous work [I. Bialynicki-Birula, Phys. Rev. Lett. {\bf 93}, 20402 (2004)] is extended to cover more realistic examples of electromagnetic waves, viz. the Bessel beams. It is shown that electrons may be guided by a Bessel beam with nonvanishing orbital angular momentum. The mechanism for trapping the electrons near the electromagnetic vortex line of such a wave field is the same as for the Trojan states of Rydberg electrons produced by a circularly polarized wave. The main difference is that in the present case the transverse motion of electrons in a beam is confined under the action of the electromagnetic wave alone, no additional attraction center is required. We also discuss briefly the motion of electrons in Neumann and Hankel beams.
Physics/0502025 (February 2005)
Free Electrons Generation in the Interaction of Intense Laser Pulses with Atomic Clusters
M. Rusek and A. Orłowski
Interaction of argon clusters with intense laser pulses is studied theoretically. Free electrons energy distribution is studied. Differences between infrared and vacuum ultraviolet frequency regimes are pointed out. Clear physical interpretation of the obtained results is given.
ACTA PHYS. POLONICA A Vol. 107 (2005)
Interaction of argon clusters with intense laser pulses is studied theoretically. Free electrons energy distribution is studied. Differences between infrared and vacuum ultraviolet frequency regimes are pointed out. Clear physical interpretation of the obtained results is given.
ACTA PHYS. POLONICA A Vol. 107 (2005)
Aug 23, 2004
Probabilistic models of income distributions.
Piotr Łukasiewicz and Arkadiusz Orłowski
The results showing relationships between distributions of individual incomes and incomes of two-earners households are presented. It is shown that individual incomes are very well described by Dagum's distributions. Income distributions in two quite different countries (USA and Poland) are studied for comparison. Obtained results show very striking and interesting differences.
Physica A Vol. 344, 1-2
The results showing relationships between distributions of individual incomes and incomes of two-earners households are presented. It is shown that individual incomes are very well described by Dagum's distributions. Income distributions in two quite different countries (USA and Poland) are studied for comparison. Obtained results show very striking and interesting differences.
Physica A Vol. 344, 1-2
Aug 20, 2004
Application of bootstrap to detecting chaos in financial time series
Katarzyna Brzozowska-Rup and Arkadiusz Orłowski
A moving blocks bootstrap procedure is used to investigate the dynamics of nominal exchange rates and the return rates of the US Dollar against the Polish Zloty. The problem if these financial time series exhibit chaotic behavior is undertaken. A possibility of detecting the presence of a positive Lyapunov exponent is studied.
Physica A. 344, 1-2
A moving blocks bootstrap procedure is used to investigate the dynamics of nominal exchange rates and the return rates of the US Dollar against the Polish Zloty. The problem if these financial time series exhibit chaotic behavior is undertaken. A possibility of detecting the presence of a positive Lyapunov exponent is studied.
Physica A. 344, 1-2
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