aktualisiertes pdf - DPG-Tagungen

Q 11.2 Mo 16:45 HS 224
Robust and Efficient Addressing of Single Atoms Using
Adiabatic Passages — •Yevhen Miroshnychenko, Dominik
Schrader, Mkrtych Khudaverdyan, Igor Dotsenko, Stefan
Kuhr, Wolfgang Alt, Arno Rauschenbeutel, and Dieter
Meschede — Institut für Angewandte Physik, Universität Bonn,
Wegelerstr. 8, Bonn, 53115
We have used the method of adiabatic passages to address single neutral
Cs atoms stored in an optical standing wave dipole trap [1]. The
main advantage of the method of adiabatic passages for the purpose of
full population transfer in a two level system, in contrast to resonant
pi-pulses, is its robustness with respect to fluctuations of the amplitude
and the frequency of an external field, and of the resonance frequency of
an atom.
We apply a microwave sweep to the outermost mF magnetic sublevels
of the two hyperfine ground states of Cs. We use a magnetic field gradient
along the dipole trap axis to induce position dependent Zeeman shifts of
hyperfine levels of different atoms in the dipole trap. Setting the central
frequency of the microwave pulse to the Zeeman resonance frequency of a
selected atom we robustly and with near 100% transfer the population of
this atom only out of the string of atoms in the trap. We discuss results
of the numerical simulation and the corresponding experiments [2].
[1] S. Kuhr et. al., Science 293, 278 (2001)
[2] M. Khudaverdyan et. al., in preparation
Q 11.3 Mo 17:00 HS 224
Towards atom-photon entanglement — •Daniel Schlenk 1 ,
Markus Weber 1 , Juergen Volz 1 , Johannes Vrana 1 , Christian
Kurtsiefer 2 , and Harald Weinfurter 1,3 — 1 Sektion Physik der
LMU Muenchen — 2 National University of Singapore — 3 Max-Planck
Institut fuer Quantenoptik, Garching
Conservation of angular momentum during spontaneous decay of a
lambda-type atomic transition generates a spin entangled state between
the atom and the emitted photon. A localized single atom in a far-offresonant
dipole trap offers the opportunity to investigate the non-classical
correlation properties of such an entangled atom-photon state.
In our experiment we load a single Rb87 atom from a sample of laser
cooled atoms into an optical dipole trap. The observed photon antibunching
in the atomic fluorescence light verifies the presence of single
atoms inside our trap. We report on state selective detection measurements
of a single Rb atom using a combination of a dark-state-projection
and a STIRAP technique. This measurement is the key ingredient in order
to analyze the spin correlations and to determine the amount of
entanglement in our atom-photon system.
Q 11.4 Mo 17:15 HS 224
Normal-mode spectrum of a single intracavity atom. —
•T. Puppe, P. Maunz, I. Schuster, N. Syassen, P.W.H.
Pinkse, and G. Rempe — Max-Planck-Institut für Quantenoptik,
Hans-Kopfermann-Str. 1, 85748 Garching, Germany
The normal-mode splitting is the characteristic signature of the fundamental
interaction of an individual atom with a single mode of the light
field. The measurement of the normal-mode spectrum has been complicated
by variations of the mean atom number in beam experiments as
well as fluctuations of the atom-cavity coupling due to atomic motion.
Here, single laser-cooled atoms are trapped in a far-detuned intracavity
dipole trap [1] upon detection. Periods of cavity cooling [2] are sandwitched
between the probe intervals to further localise the atom and
monitor the coupling at the same time. This preparation of a single, well
localised atom strongly coupled to an optical mode allows to measure a
well resolved normal-mode splitting in two ways: The mean transmission
of the near-resonant cavity-QED field represents the cavity excitation
spectrum. Moreover, also the spectrum of the excitation of the atom as
the second component of the strongly coupled system could be measured
for the first time: In the presence of cavity cooling, trap loss is caused
by spontaneously scattered photons. The atomic excitation is therefore
inversely proportional to the storage time.
[1] J. Ye, D.W. Vernooy, and H.J. Kimble, Phys. Rev. Lett. 83, 4987
(1999).
[2] P. Maunz et al., to be published. P. Horak et al. Phys. Rev. Lett. 79,
4974 (1997). V. Vuletić and S. Chu, Phys. Rev. Lett. 84, 3787 (2000).
87
Q 11.5 Mo 17:30 HS 224
Deterministic Control of Atom-Cavity Coupling — •B. Weber,
S. Nußmann, M. Hijlkema, F. Rohde, A. Kuhn, and G. Rempe —
Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85741
Garching
We present an experimental setup to achieve deterministic control of
the coupling of a single Rb atom to a high-finesse optical cavity. By means
of an optical dipole force trap made of a single running-wave laser beam
we transport cold atoms from a magneto-optical trap over a distance of 14
mm into the mode volume of the cavity. With the cavity used as an atom
detector, we observe the arrival of the atom cloud as well as characteristic
single-atom transit signals in the transmitted intensity. Trapping the
atoms by means of a standing-wave laser field inside the cavity will allow
us to generate long streams of single photons for quantum information
processing.
Q 11.6 Mo 17:45 HS 224
Kühlung bei positiver Verstimmung — •Ch. Schwedes 1 , Th. Becker
1 , J. von Zanthier 1 , H. Walther 1 und E. Peik 2 — 1 MPI f.
Quantenopik, Hans-Kopfermann-Str. 1, 85748 Graching — 2 PTB, Bundesallee
100, 38116 Braunschweig
Eine experimentelle und theoretische Untersuchung von Laser Seitenbandkühlung
bei positiver Verstimmung eines in einer RF-Falle gespeicherten
Ions für wird präsentiert. Der Einfluß der Mikrobewegung im
zeitabängigen Potential einer Paulfalle kann zu der überraschenden Situation
führen, dass Seitenbandkühlung für positive Werte der Laserverstimmung
möglich wird, das heißt, für eine Laserfrequenz die über der
Resonanzfrequenz des ruhenden Ions liegt. Die Kühlrate und der Einfangbereich
werden in einem semiklassischen Modell berechnet. Experimentelle
Ergebnisse des Effektes werden anhand eines einzelnen In + -Ions
geliefert, das in einer miniaturisierten Paulfalle gespeichert ist.
Q 11.7 Mo 18:00 HS 224
Laser Cooling of an Indium Atomic Beam — •Ruby dela
Torre, Jiayu Wang, Bernard Kloeter, Dietmar Haubrich, Ulrich
Rasbach, and Dieter Meschede — Institut fuer Angewandte
Physik, Universitaet Bonn, Wegelerstr. 8, 53115 Bonn, Germany
Laser cooled atomic beams are the method of choice for Atomic
Nanofabrication (ANF) where high deposition rates are needed. We have
realized the transverse cooling of an Indium atomic beam. One scheme
employs radiation pressure cooling and another scheme involves a bluedetuned
standing-wave configuration. Two-wavelength laser sources, at
410nm and 451nm, were used in both methods. We will present our systematic
studies on these cooling schemes.
Q 11.8 Mo 18:15 HS 224
Real-time measurement of a single ion trajectory — •Pavel Bushev,
Alex Wilson, Jürgen Eschner, and Rainer Blatt — Institut
für Experimentalphysik, Universität Innsbruck, Technikerstraße 25,
A-6020 Innsbruck, Austria
In our experiment a single Ba + ion is held by a Paul trap and continuously
Doppler cooled with a laser. The residual thermal motion of the
ion in the trap has an average amplitude of about 35 nm at a frequency
of 1 MHz. A collimating lens and a distant mirror are placed such that
part of the scattered light is retro-reflected, thus leading to interference
of high contrast. Hence, the phase of the interference fringes are sensitive
to the ion-mirror distance [1]. In this case the photocurrent contains
all the information about the ion’s motion. Its amplitude and phase are
detected with a high signal-to-noise-ratio.
By using a phase-locking technique we are able to observe the ion trajectory
with an accuracy of 10 nm within a measurement time of 10 ms.
We also report first attempts to cool a single atomic particle (the Ba +
ion), beyond the Doppler-cooling-limit using electronic feedback. We create
an additional friction force, which is proportional the ”instantaneous
speed” of the ion in the trap, by supplying additional electric fields along
the direction of the ion’s motion. A dip in the motional spectrum appears
when this external friction force is applied.
[1] J. Eschner et al., Nature 413, 495-498, (2001)
Q 11.9 Mo 18:30 HS 224
Thermisch angeregte Ionen-“Moleküle” — •M. Loewen 1 und
Chr. Wunderlich 2 — 1 I. Institut für Theoretische Physik, Universität
Hamburg, Jungiusstr. 9, 20355 Hamburg — 2 Institut für Laser-Physik,
Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg