446 research outputs found
Floquet engineering of correlated tunneling in the Bose-Hubbard model with ultracold atoms
We report on the experimental implementation of tunable occupation-dependent
tunneling in a Bose-Hubbard system of ultracold atoms via time-periodic
modulation of the on-site interaction energy. The tunneling rate is inferred
from a time-resolved measurement of the lattice site occupation after a quantum
quench. We demonstrate coherent control of the tunneling dynamics in the
correlated many-body system, including full suppression of tunneling as
predicted within the framework of Floquet theory. We find that the tunneling
rate explicitly depends on the atom number difference in neighboring lattice
sites. Our results may open up ways to realize artificial gauge fields that
feature density dependence with ultracold atoms.Comment: 8 pages, 9 figure
Quantum state engineering on an optical transition and decoherence in a Paul trap
A single Ca+ ion in a Paul trap has been cooled to the ground state of
vibration with up to 99.9% probability. Starting from this Fock state |n=0> we
have demonstrated coherent quantum state manipulation on an optical transition.
Up to 30 Rabi oscillations within 1.4 ms have been observed. We find a similar
number of Rabi oscillations after preparation of the ion in the |n=1> Fock
state. The coherence of optical state manipulation is only limited by laser and
ambient magnetic field fluctuations. Motional heating has been measured to be
as low as one vibrational quantum in 190 ms.Comment: 4 pages, 5 figure
Model for the hyperfine structure of electronically-excited molecules
A model for determining the hyperfine structure of the excited electronic
states of diatomic bialkali heteronuclear molecules is formulated from the
atomic hyperfine interactions, and is applied to the case of bosonic KCs
and fermionic KCs molecules. The hyperfine structure of the potential
energy curves of the states correlated to the
K(4s\,^2S_{1/2})+Cs(6p\,^2P_{1/2,3/2}) dissociation limits is described in
terms of different coupling schemes depending on the internuclear distance .
These results provide the first step in the calculation of the hyperfine
structure of rovibrational levels of these excited molecular states in the
perspective of the identification of efficient paths for creating ultracold
ground-state KCs molecules.Comment: 12 pages, 15 figure
Observation of interspecies Feshbach resonances in an ultracold Rb-Cs mixture
We report on the observation of interspecies Feshbach resonances in an
ultracold, optically trapped mixture of Rb and Cs atoms. In a magnetic field
range up to 300 G we find 23 interspecies Feshbach resonances in the lowest
spin channel and 2 resonances in a higher channel of the mixture. The
extraordinarily rich Feshbach spectrum suggests the importance of different
partial waves in both the open and closed channels of the scattering problem
along with higher-order coupling mechanisms. Our results provide, on one hand,
fundamental experimental input to characterize the Rb-Cs scattering properties
and, on the other hand, identify possible starting points for the association
of ultracold heteronuclear RbCs molecules.Comment: 7 pages, 3 figures, 1 tabl
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