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investigations of saturation effects are discussed.
In addititon, we study cooling processes, in particular Raman sideband
cooling [1], in the QUEST in a new experimental setup. The aim is to create
a Bose-Einstein condensate [2] as a cooling agent to sympathetically
cool the lithium into quantum degeneracy.
[1] A. J. Kerman et al., Phys. Rev. Lett. 84, 439 (2000)
[2] M. D. Barrett et al., Phys. Rev. Lett. 87, 010404 (2001), G. Cennini
et al., Phys.Rev. Lett. 91, 240408 (2003)
Q 38.3 Do 14:00 Schellingstr. 3
Towards Formation of a Metastable Calcium BEC — •Dirk
Hansen, Janis Mohr, Ciprian Zafiu, and Andreas Hemmerich
— Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149,
22761 Hamburg
Alkaline-earth-metal atoms provide a unique combination of interesting
spectroscopic features connected to their two valence electrons. The
resulting singlet and triplet states offer strong principle fluorescence lines
well suited for laser cooling as well as narrow-band intercombination transitions
that can be used for refined laser cooling schemes. The metastable
3 P2, mJ = 2 state is an interesting candidate for magnetic trapping and
the formation of a Bose-Einstein-Condensate (BEC).
Efficient production and magnetic trapping of cold metastable Calcium
has recently been demonstrated in our group [1-2]. In this poster,
we report on modifications of the experimental setup, which promise significant
improvements in particle number, temperature, and density. The
prospects of evaporative cooling and BEC-formation in a miniature Ioffe
- Pritchard trap are discussed.
[1] J. Grünert, S. Ritter, and A. Hemmerich, Phys. Rev. A 65,
041401(R) (2002)
[2] D. Hansen, J. Mohr, A. Hemmerich, Phys. Rev. A 67, 021401(R)
(2003)
Q 38.4 Do 14:00 Schellingstr. 3
Improved upper bound on the ground-state energy of a homogeneous
Bose-Einstein condensate — •Christoph Weiss and
André Eckardt — Institut für Physik, Universität Oldenburg, D-
26129 Oldenburg, Germany
The standard calculations of the ground-state energy of a homogeneous
Bose-Einstein condensate rely on certain approximations which appear
physically reasonable, but are difficult to control. Therefore, mathematically
rigorous bounds on the ground-state energy are of particular importance.
The derivation of such bound was pioneered by Dyson already
in 1957 [1]. While his lower bound could recently be increased by a factor
of 14 by Lieb and Yngvason [2], his upper bound [1] has remained
essentially unchanged. Here, an improved, rigorous upper bound on the
ground-state energy is established.
[1] F.J. Dyson, Phys. Rev. 106, 20 (1957).
[2] E.H. Lieb and J. Yngvason, Phys. Rev. Lett. 80, 2504 (1998).
Q 38.5 Do 14:00 Schellingstr. 3
Order and chaos in the electrodynamic trapping of slow polar
molecules. — •P.W.H. Pinkse, E. Schmidt, T. Junglen, T.
Rieger, S.A. Rangwala, and G. Rempe — Max-Planck-Institut für
Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany
In the last few years, magnetic and electrostatic trapping of selected
slow molecules has been demonstrated. For molecules with permanent
dipole moments, new techniques are required to allow simultaneous trapping
of atoms and molecules in various internal states. This would, for
instance, allow cold collision studies and applications of slow molecules
in precision spectroscopy. Recently, we demonstrated two-dimensional
trapping of dipolar molecules in an electrodynamic four-wire trap [1], as
reported in a contribution by Junglen et al. This technique has the capability
to trap low- and high-electric field seeking states simultaneously.
Hence, in principal, atoms could also be trapped. In this contribution we
analyse the motion of molecules in our two-dimensional electrodynamic
trap. The motion of molecules in the central, harmonic part of trap is well
understood. However, numerical simulations have shown that the anharmonicities
away from the centre play an important role. Indeed, the calculated
molecular trajectories show strong evidence of chaotic behaviour.
We illustrate the cross-over from the regular to the chaotic regime, using
a set of diagnostic tools for chaos such as Poincaré maps, power spectrum
analysis, trajectory separation, and Lyapunov exponents.
[1] T. Junglen, T. Rieger, S.A. Rangwala, P.W.H. Pinkse, and G. Rempe,
arXiv:physics/0310046
120
Q 38.6 Do 14:00 Schellingstr. 3
Localising a single atom in a cavity-QED field — •N. Syassen, P.
Maunz, I. Schuster, T. Puppe, P.W.H. Pinkse, and G. Rempe —
Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748
Garching, Germany
A single atom trapped in the field mode of a small high-finesse cavity
forms the paradigm of cavity-QED. Questions in fundamental quantum
optics, like investigations on quantum measurement can be addressed
in such a system. Moreover, fascinating applications in quantuminformation
processing and quantum computing are being developed. For
many of these applications, trapping of an atom in the cavity mode alone
is not enough. Ideally, the atom should not move and be perfectly localized
at the antinode of the cavity-QED field.
Here we analyse the localisation of a single atom stored in an intracavity
dipole trap. Cavity cooling [1,2] as presented in talk Q6.1 is used
to improve the localisation and to compensate for heating introduced by
probing the atom-cavity system. Resolving the normal modes of the coupled
system is only possible for a large and constant enough coupling.
Once the normal modes are resolved, the broadening of the normal-mode
resonances allows us to investigate the variation in coupling strength and
hence how well the atom is localized.
[1] P. Horak et al. H. Ritsch, Phys. Rev. Lett. 79, 4974 (1997). V.
Vuletić and S. Chu, Phys. Rev. Lett. 84, 3787 (2000).
[2] P. Maunz, T. Puppe, I. Schuster, N. Syassen, P.W.H Pinkse, and G.
Rempe, to be published.
Q 38.7 Do 14:00 Schellingstr. 3
Analysis of the motion of a single atom in a cavity dipole
trap. — •I. Schuster, P. Maunz, T. Puppe, N. Syassen, P.W.H.
Pinkse, and G. Rempe — Max-Planck-Institut für Quantenoptik,
Hans-Kopfermann-Str. 1, 85748 Garching, Germany
In the regime of strong coupling, the motion of a single atom inside
a high-finesse cavity can directly be observed since the position of the
atom has a large influence on the light intensity within the cavity [1].
In our experiment, the atom is captured in an additional far-detuned
standing-wave dipole trap [2]. The radial oscillation of the atom in the
trap is clearly visible in the time-resolved transmission signal of the nearresonant
cavity-QED field. The axial oscillation frequency is two orders
of magnitude larger but can be resolved in the autocorrelation function
of the transmitted light by virtue of the high detection bandwidth. The
interdependence between axial and radial oscillation is examined. The
motion of the atom inside the dipole trap is studied for different trap
parameters.
[1] P.W.H. Pinkse, T. Fischer, P. Maunz, and G. Rempe, Nature 404,
365 (2000). C.J. Hood, T.W. Lynn, A.C. Doherty, A.S. Parkins, and
H.J. Kimble. Science 287, 1447 (2000).
[2] J. Ye, D.W. Vernooy, and H.J. Kimble, Phys. Rev. Lett. 83, 4987
(1999).
Q 38.8 Do 14:00 Schellingstr. 3
Continued Observation and Absolute Position Control
of Single Neutral Atoms — •Mkrtych Khudaverdyan,
Dominik Schrader, Yevhen Miroshnychenko, Igor Dotsenko,
Wolfgang Alt, Stefan Kuhr, Wenjamin Rosenfeld,
Arno Rauschenbeutel, and Dieter Meschede — Institut für
Angewandte Physik, Universität Bonn, Wegelerstr. 8, Bonn, 53115
Using an intensified CCD camera we spatially resolve Caesium atoms,
confined to the potential wells of a standing wave optical dipole trap
with diffraction limited resolution. The atoms are illuminated by a reddetuned
optical molasses, which induces the fluorescence light and cools
the atoms at the same time. Using this technique, we have continuously
imaged the controlled motion of a single atom as well as of a small number
of distinguishable atoms with observation times exceeding one minute
[1].
The absolute position of an atom can be controlled using our optical
conveyor belt [2, 3] in combination with a feedback loop. The initial position
of the atom in the dipole trap is determined using the intensified
CCD camera. Then, the atom is transported to the desired target position
with sub-micrometer precision. The current precision of the position
feedback is 400 nm and is determined by the resolution of the atom in
the dipole trap. This position control is an important prerequisite for
introducing atoms into an optical resonator, which will enable controlled
interaction between two or more atoms.
[1] Y.Miroshnychenko et al., Optics Express (in print)
[2] S. Kuhr et al., Science 293, 278 (2001)