aktualisiertes pdf - DPG-Tagungen

und Energieeigenwerte semiklassisch aus den Bahndaten der im Kern
geschlossenen klassischen Bahnen zu gewinnen. In Systemen mit weichen
Potenzialen wie zum Beispiel dem Wasserstoffatom im Magnetfeld
stossen einfache shooting- oder biscetion-Methoden bei der Bahnsuche
jedoch schnell an Grenzen. Mittels eines Multishooting Verfahrens, in
Kombination mit ihrer symbolischen Dynamik, lässt sich die Bahnsuche
A 3 Kalte Atome in Fallen
systematisieren. Damit lassen sich extrem lange und instabile Bahnen berechnen.
Es wurden auf diese Weise ca. 16 Millionen Bahnen für das diamagnetische
Wasserstoffatom bestimmt! Sie bilden die Grundlage für die
semiklassische Berechnung des Photoabsorbtionsspektrums und, mittels
Harmonischer Inversion, individueller Energieeigenwerte und Übergangsdipolmatrixelemente.
Zeit: Montag 14:00–15:15 Raum: HS 132
A 3.1 Mo 14:00 HS 132
Atomic Scattering on Bose-Einstein Condensates — •Joachim
Brand, Ivo Häring, and Jan Michael Rost — Max-Planck-Institut
für Physik komplexer Systeme
A relation between the number of bound collective excitations of an
atomic Bose-Einstein condensate and the phase shift of elastically scattered
atoms is derived. Within the Bogoliubov model of a weakly interacting
Bose gas this relation is exact and generalises Levinson’s theorem.
Specific features of the Bogoliubov model such as complex-energy modes,
continuum bound states, and Fano resonances are discussed and a numerical
example is given.
A 3.2 Mo 14:15 HS 132
Kohaerenete Kontrolle fuer ein Modellpotential und das Helium
Atom — •Imre F. Barna, Andreas Becker und Jan-Michael
Rost — Max-Planck-Institute fuer Physik komplexer Systeme
Mit dem genetischen Algoritmus berechnen wir optimierte phasenmodulierte
kurze XUV Laserpulse fuer die Anregung und Ionisation und
gewinnen bis zu zwei Groessenordnungen in den Uebergangswahrscheinlichkeiten.
Wir untersuchen ein Kastenpotentialmodell mit wenig gebundenen
Zustaenden um den berechneten Kontrollmechanismus des Heliumatoms
zu verstehen. Das Laserfeld wird klassisch behandelt und die
Elektronendynamik durch die zeitabhaengige Schroedingergleichung ermittelt.
A 3.3 Mo 14:30 HS 132
The Temperature of a single Ion in a Penning trap — •Slobodan
Djekic, Joseba Alonso, Fernando Galve, Stefan Stahl, Tristan
Valenzuela, José Verdú, Manuel Vogel, and Günther
Werth — Institut f ür Physik, Universität Mainz, Germany
We have developed several independent methods to determine the temperature
of single ion stored in a Penning trap and applied them to a
single 12 C 5+ ion that has been stored for several weeks. The ion’s trapping
motions are monitored by their induced image currents upon the
trap electrodes and the attached resonance circuits. A Fourier transform
analyis of the detection signal in the resonance circuits then yields information
both on the motional frequencies and relative amplitudes and
A 5 Neue Aspekte der Atomphysik I
their response to external excitation. The results of the different methods
agree within their uncertainties and represent an example for a system
where a temperature can be assigned to a single particle in a thermal
equilibrium with its surrounding by use of the ergodic principle.
A 3.4 Mo 14:45 HS 132
Ultracold Fermi and Bose gases in exotic optical lattices.
— •Mikhail Baranov 1 , Hans-Ulrich Everts 1 , Henning
Fehrmann 1 , Luis Santos 1 , Ignacio Cirac 2,3 , and Maciek
Lewenstein 1,3 — 1 Institüt für Theoretische Physik, Universität
Hannover, 30167 Hannover, Germany — 2 Max Plank Institüt für
Quantenoptic, 85748 Garching, Germany — 3 Institut de Ciéncies
Fotóniques, Barcelona 08034, Spain
We study the phase diagram of ultracold quantum degenerate Fermi
and Bose gases and thier mixtures in frustrated optical lattices, i.e.
Kagome lattice and its trimerized modification. Placed in such a lattice,
quantum gases demonstrate very reach phase diagrams, and can be
used as a tool for modelling the behaviour of quantum fructrated antiferromagnets.
A 3.5 Mo 15:00 HS 132
N-component Bose-Einstein condensate in an optical lattice —
•Christopher Moseley and Klaus Ziegler — Lehrstuhl für theoretische
Physik II, Institut für Physik, Universität Augsburg, Universitätsstr.
1, 86135 Augsburg
We consider an N-component system of hard-core bosons in an optical
lattice. On each lattice site a boson can occupy one of the N different
states. Tunneling is possible between neighbouring lattice sites as well as
between the states. In our model, the limit N → ∞ can be solved exactly.
This case represents a Bose-Einstein condensate where interactions play
a minor role due to the large number of possible states.The influence of
the hard-core interaction in a system with finite N can be investigated
by means of a 1/N-expansion. This approach allows the determination
of several physical quantities like the density of the condensate, the condensate
fraction and the dispersion relation and density of states of quasi
particles. The zero temperature phase diagram is investigated.
Zeit: Montag 16:30–18:00 Raum: HS 132
A 5.1 Mo 16:30 HS 132
Attosecond entanglement of protons and electrons in condensed
matter - Compton scattering results and theoretical considerations
— •C. Aris C.-Dreismann 1 and Tyno Abdul-Redah 1,2
— 1 Inst. f. Chemie, Stranski Lab., TU Berlin, D-10623 Berlin — 2 ISIS
Facility, R.A.L., Oxfordshire, OX11 0QX, U.K.
Several experiments on liquid and solid samples containing protons
show a striking shortfall in the intensity of epithermal neutrons scattered
by the protons [1-3]. E.g., neutrons colliding with water for just
attoseconds (as) will see a ratio of H to O of roughly 1.5 to 1, instead of
2 to 1 [1,3]. Due to the large energy and momentum transfers applied in
these neutron Compton scattering (NCS) experiments, the duration of
a neutron-proton scattering event is about 50-500 as. Very recently [2,3]
this effect has been confirmed using electron-proton Compton scattering
(ECS) from a solid polymer [2,3]. Recall that electrons and neutrons interact
with protons via fundamentally different forces – electromagnetic
and strong. Theoretical considerations support the presence of attosecond
quantum entanglement in the dynamics of the protons and the surrounding
electrons. Note also that the time window of NCS and ECS is equal
to the characteristic time of ’electron motion’, so that the widely used
11
Born-Oppenheimer approximation is not applicable here.
[1] C. A. Chatzidimitriou-Dreismann et al., Phys. Rev. Lett. 79, 2839
(1997). [2] C. A. Chatzidimitriou-Dreismann et al. Phys. Rev. Lett. 91,
057403 (2003). [3] Cf.: Physics Today, sect. ’Physics Update’, p. 9, Sept.
2003; Scientific American, sect. ’News Scan’, p. 20, Oct. 2003
A 5.2 Mo 16:45 HS 132
Quantenreflexionsphasen von Casimir-van der Waals-
Potentialen — •Alexander Jurisch und Harald Friedrich —
Physik-Department, Technische Universität München, 85747 Garching
bei München
Wir untersuchen die Phase der Reflexionsamplitude für Quantenreflexion
von Atomen an attraktiven Potentialschwänzen vom Casimir-van
der Waals-Typ. Die Kenntnis dieser Phasen erlaubt es die vom Potential
induzierte Orts- und Zeitverschiebung der Atome relativ zu freien
Atomen zu berechnen. Aus dem Schwellenverhalten der Quantenreflexionsphase
kann eine effektive Streulänge berechnet werden, deren Verhalten
Aufschluß über die relative Dominanz der inneren Längenskalen des
Casimir-van der Waals-Potentials gibt.